| blob | 2d4a14c8d0be23d20696b3a47842b891e4118e3a |
1 /*
2 ** 2001 September 15
3 **
4 ** The author disclaims copyright to this source code. In place of
5 ** a legal notice, here is a blessing:
6 **
7 ** May you do good and not evil.
8 ** May you find forgiveness for yourself and forgive others.
9 ** May you share freely, never taking more than you give.
10 **
11 *************************************************************************
12 ** This file contains routines used for analyzing expressions and
13 ** for generating VDBE code that evaluates expressions in SQLite.
14 */
17 /* Forward declarations */
21 /*
22 ** Return the affinity character for a single column of a table.
23 */
27 }
29 /*
30 ** Return the 'affinity' of the expression pExpr if any.
31 **
32 ** If pExpr is a column, a reference to a column via an 'AS' alias,
33 ** or a sub-select with a column as the return value, then the
34 ** affinity of that column is returned. Otherwise, 0x00 is returned,
35 ** indicating no affinity for the expression.
36 **
37 ** i.e. the WHERE clause expressions in the following statements all
38 ** have an affinity:
39 **
40 ** CREATE TABLE t1(a);
41 ** SELECT * FROM t1 WHERE a;
42 ** SELECT a AS b FROM t1 WHERE b;
43 ** SELECT * FROM t1 WHERE (select a from t1);
44 */
53 }
55 #ifndef SQLITE_OMIT_CAST
59 }
60 #endif
63 }
68 );
69 }
71 }
73 /*
74 ** Set the collating sequence for expression pExpr to be the collating
75 ** sequence named by pToken. Return a pointer to a new Expr node that
76 ** implements the COLLATE operator.
77 **
78 ** If a memory allocation error occurs, that fact is recorded in pParse->db
79 ** and the pExpr parameter is returned unchanged.
80 */
86 ){
93 }
94 }
96 }
98 Token s;
102 }
104 /*
105 ** Skip over any TK_COLLATE operators and any unlikely()
106 ** or likelihood() function at the root of an expression.
107 */
118 }
119 }
121 }
123 /*
124 ** Return the collation sequence for the expression pExpr. If
125 ** there is no defined collating sequence, return NULL.
126 **
127 ** See also: sqlite3ExprNNCollSeq()
128 **
129 ** The sqlite3ExprNNCollSeq() works the same exact that it returns the
130 ** default collation if pExpr has no defined collation.
131 **
132 ** The collating sequence might be determined by a COLLATE operator
133 ** or by the presence of a column with a defined collating sequence.
134 ** COLLATE operators take first precedence. Left operands take
135 ** precedence over right operands.
136 */
147 }
151 }
155 ){
156 /* op==TK_REGISTER && p->pTab!=0 happens when pExpr was originally
157 ** a TK_COLUMN but was previously evaluated and cached in a register */
162 }
164 }
170 /* The Expr.x union is never used at the same time as Expr.pRight */
172 /* p->flags holds EP_Collate and p->pLeft->flags does not. And
173 ** p->x.pSelect cannot. So if p->x.pLeft exists, it must hold at
174 ** least one EP_Collate. Thus the following two ALWAYS. */
181 }
182 }
183 }
185 }
188 }
189 }
192 }
194 }
196 /*
197 ** Return the collation sequence for the expression pExpr. If
198 ** there is no defined collating sequence, return a pointer to the
199 ** defautl collation sequence.
200 **
201 ** See also: sqlite3ExprCollSeq()
202 **
203 ** The sqlite3ExprCollSeq() routine works the same except that it
204 ** returns NULL if there is no defined collation.
205 */
211 }
213 /*
214 ** Return TRUE if the two expressions have equivalent collating sequences.
215 */
220 }
222 /*
223 ** pExpr is an operand of a comparison operator. aff2 is the
224 ** type affinity of the other operand. This routine returns the
225 ** type affinity that should be used for the comparison operator.
226 */
230 /* Both sides of the comparison are columns. If one has numeric
231 ** affinity, use that. Otherwise use no affinity.
232 */
237 }
239 /* Neither side of the comparison is a column. Compare the
240 ** results directly.
241 */
244 /* One side is a column, the other is not. Use the columns affinity. */
247 }
248 }
250 /*
251 ** pExpr is a comparison operator. Return the type affinity that should
252 ** be applied to both operands prior to doing the comparison.
253 */
267 }
269 }
271 /*
272 ** pExpr is a comparison expression, eg. '=', '<', IN(...) etc.
273 ** idx_affinity is the affinity of an indexed column. Return true
274 ** if the index with affinity idx_affinity may be used to implement
275 ** the comparison in pExpr.
276 */
286 }
287 }
289 /*
290 ** Return the P5 value that should be used for a binary comparison
291 ** opcode (OP_Eq, OP_Ge etc.) used to compare pExpr1 and pExpr2.
292 */
297 }
299 /*
300 ** Return a pointer to the collation sequence that should be used by
301 ** a binary comparison operator comparing pLeft and pRight.
302 **
303 ** If the left hand expression has a collating sequence type, then it is
304 ** used. Otherwise the collation sequence for the right hand expression
305 ** is used, or the default (BINARY) if neither expression has a collating
306 ** type.
307 **
308 ** Argument pRight (but not pLeft) may be a null pointer. In this case,
309 ** it is not considered.
310 */
314 Expr *pRight
315 ){
326 }
327 }
329 }
331 /*
332 ** Generate code for a comparison operator.
333 */
342 ){
353 }
355 /*
356 ** Return true if expression pExpr is a vector, or false otherwise.
357 **
358 ** A vector is defined as any expression that results in two or more
359 ** columns of result. Every TK_VECTOR node is an vector because the
360 ** parser will not generate a TK_VECTOR with fewer than two entries.
361 ** But a TK_SELECT might be either a vector or a scalar. It is only
362 ** considered a vector if it has two or more result columns.
363 */
366 }
368 /*
369 ** If the expression passed as the only argument is of type TK_VECTOR
370 ** return the number of expressions in the vector. Or, if the expression
371 ** is a sub-select, return the number of columns in the sub-select. For
372 ** any other type of expression, return 1.
373 */
383 }
384 }
386 /*
387 ** Return a pointer to a subexpression of pVector that is the i-th
388 ** column of the vector (numbered starting with 0). The caller must
389 ** ensure that i is within range.
390 **
391 ** If pVector is really a scalar (and "scalar" here includes subqueries
392 ** that return a single column!) then return pVector unmodified.
393 **
394 ** pVector retains ownership of the returned subexpression.
395 **
396 ** If the vector is a (SELECT ...) then the expression returned is
397 ** just the expression for the i-th term of the result set, and may
398 ** not be ready for evaluation because the table cursor has not yet
399 ** been positioned.
400 */
409 }
410 }
412 }
414 /*
415 ** Compute and return a new Expr object which when passed to
416 ** sqlite3ExprCode() will generate all necessary code to compute
417 ** the iField-th column of the vector expression pVector.
418 **
419 ** It is ok for pVector to be a scalar (as long as iField==0).
420 ** In that case, this routine works like sqlite3ExprDup().
421 **
422 ** The caller owns the returned Expr object and is responsible for
423 ** ensuring that the returned value eventually gets freed.
424 **
425 ** The caller retains ownership of pVector. If pVector is a TK_SELECT,
426 ** then the returned object will reference pVector and so pVector must remain
427 ** valid for the life of the returned object. If pVector is a TK_VECTOR
428 ** or a scalar expression, then it can be deleted as soon as this routine
429 ** returns.
430 **
431 ** A trick to cause a TK_SELECT pVector to be deleted together with
432 ** the returned Expr object is to attach the pVector to the pRight field
433 ** of the returned TK_SELECT_COLUMN Expr object.
434 */
439 ){
443 /* The TK_SELECT_COLUMN Expr node:
444 **
445 ** pLeft: pVector containing TK_SELECT. Not deleted.
446 ** pRight: not used. But recursively deleted.
447 ** iColumn: Index of a column in pVector
448 ** iTable: 0 or the number of columns on the LHS of an assignment
449 ** pLeft->iTable: First in an array of register holding result, or 0
450 ** if the result is not yet computed.
451 **
452 ** sqlite3ExprDelete() specifically skips the recursive delete of
453 ** pLeft on TK_SELECT_COLUMN nodes. But pRight is followed, so pVector
454 ** can be attached to pRight to cause this node to take ownership of
455 ** pVector. Typically there will be multiple TK_SELECT_COLUMN nodes
456 ** with the same pLeft pointer to the pVector, but only one of them
457 ** will own the pVector.
458 */
463 }
468 }
470 }
472 /*
473 ** If expression pExpr is of type TK_SELECT, generate code to evaluate
474 ** it. Return the register in which the result is stored (or, if the
475 ** sub-select returns more than one column, the first in an array
476 ** of registers in which the result is stored).
477 **
478 ** If pExpr is not a TK_SELECT expression, return 0.
479 */
482 #ifndef SQLITE_OMIT_SUBQUERY
485 }
486 #endif
488 }
490 /*
491 ** Argument pVector points to a vector expression - either a TK_VECTOR
492 ** or TK_SELECT that returns more than one column. This function returns
493 ** the register number of a register that contains the value of
494 ** element iField of the vector.
495 **
496 ** If pVector is a TK_SELECT expression, then code for it must have
497 ** already been generated using the exprCodeSubselect() routine. In this
498 ** case parameter regSelect should be the first in an array of registers
499 ** containing the results of the sub-select.
500 **
501 ** If pVector is of type TK_VECTOR, then code for the requested field
502 ** is generated. In this case (*pRegFree) may be set to the number of
503 ** a temporary register to be freed by the caller before returning.
504 **
505 ** Before returning, output parameter (*ppExpr) is set to point to the
506 ** Expr object corresponding to element iElem of the vector.
507 */
515 ){
521 }
525 }
528 }
530 /*
531 ** Expression pExpr is a comparison between two vector values. Compute
532 ** the result of the comparison (1, 0, or NULL) and write that
533 ** result into register dest.
534 **
535 ** The caller must satisfy the following preconditions:
536 **
537 ** if pExpr->op==TK_IS: op==TK_EQ and p5==SQLITE_NULLEQ
538 ** if pExpr->op==TK_ISNOT: op==TK_NE and p5==SQLITE_NULLEQ
539 ** otherwise: op==pExpr->op and p5==0
540 */
546 u8 p5 /* SQLITE_NULLEQ or zero */
547 ){
561 }
566 );
599 }
614 }
615 }
617 }
619 #if SQLITE_MAX_EXPR_DEPTH>0
620 /*
621 ** Check that argument nHeight is less than or equal to the maximum
622 ** expression depth allowed. If it is not, leave an error message in
623 ** pParse.
624 */
631 );
633 }
635 }
637 /* The following three functions, heightOfExpr(), heightOfExprList()
638 ** and heightOfSelect(), are used to determine the maximum height
639 ** of any expression tree referenced by the structure passed as the
640 ** first argument.
641 **
642 ** If this maximum height is greater than the current value pointed
643 ** to by pnHeight, the second parameter, then set *pnHeight to that
644 ** value.
645 */
650 }
651 }
652 }
658 }
659 }
660 }
670 }
671 }
673 /*
674 ** Set the Expr.nHeight variable in the structure passed as an
675 ** argument. An expression with no children, Expr.pList or
676 ** Expr.pSelect member has a height of 1. Any other expression
677 ** has a height equal to the maximum height of any other
678 ** referenced Expr plus one.
679 **
680 ** Also propagate EP_Propagate flags up from Expr.x.pList to Expr.flags,
681 ** if appropriate.
682 */
692 }
694 }
696 /*
697 ** Set the Expr.nHeight variable using the exprSetHeight() function. If
698 ** the height is greater than the maximum allowed expression depth,
699 ** leave an error in pParse.
700 **
701 ** Also propagate all EP_Propagate flags from the Expr.x.pList into
702 ** Expr.flags.
703 */
708 }
710 /*
711 ** Return the maximum height of any expression tree referenced
712 ** by the select statement passed as an argument.
713 */
718 }
720 /*
721 ** Propagate all EP_Propagate flags from the Expr.x.pList into
722 ** Expr.flags.
723 */
727 }
728 }
729 #define exprSetHeight(y)
732 /*
733 ** This routine is the core allocator for Expr nodes.
734 **
735 ** Construct a new expression node and return a pointer to it. Memory
736 ** for this node and for the pToken argument is a single allocation
737 ** obtained from sqlite3DbMalloc(). The calling function
738 ** is responsible for making sure the node eventually gets freed.
739 **
740 ** If dequote is true, then the token (if it exists) is dequoted.
741 ** If dequote is false, no dequoting is performed. The deQuote
742 ** parameter is ignored if pToken is NULL or if the token does not
743 ** appear to be quoted. If the quotes were of the form "..." (double-quotes)
744 ** then the EP_DblQuoted flag is set on the expression node.
745 **
746 ** Special case: If op==TK_INTEGER and pToken points to a string that
747 ** can be translated into a 32-bit integer, then the token is not
748 ** stored in u.zToken. Instead, the integer values is written
749 ** into u.iValue and the EP_IntValue flag is set. No extra storage
750 ** is allocated to hold the integer text and the dequote flag is ignored.
751 */
757 ){
768 }
769 }
787 }
788 }
789 }
790 #if SQLITE_MAX_EXPR_DEPTH>0
792 #endif
793 }
795 }
797 /*
798 ** Allocate a new expression node from a zero-terminated token that has
799 ** already been dequoted.
800 */
805 ){
806 Token x;
810 }
812 /*
813 ** Attach subtrees pLeft and pRight to the Expr node pRoot.
814 **
815 ** If pRoot==NULL that means that a memory allocation error has occurred.
816 ** In that case, delete the subtrees pLeft and pRight.
817 */
822 Expr *pRight
823 ){
832 }
836 }
838 }
839 }
841 /*
842 ** Allocate an Expr node which joins as many as two subtrees.
843 **
844 ** One or both of the subtrees can be NULL. Return a pointer to the new
845 ** Expr node. Or, if an OOM error occurs, set pParse->db->mallocFailed,
846 ** free the subtrees and return NULL.
847 */
853 ){
856 /* Take advantage of short-circuit false optimization for AND */
864 }
866 }
869 }
871 }
873 /*
874 ** Add pSelect to the Expr.x.pSelect field. Or, if pExpr is NULL (due
875 ** do a memory allocation failure) then delete the pSelect object.
876 */
885 }
886 }
889 /*
890 ** If the expression is always either TRUE or FALSE (respectively),
891 ** then return 1. If one cannot determine the truth value of the
892 ** expression at compile-time return 0.
893 **
894 ** This is an optimization. If is OK to return 0 here even if
895 ** the expression really is always false or false (a false negative).
896 ** But it is a bug to return 1 if the expression might have different
897 ** boolean values in different circumstances (a false positive.)
898 **
899 ** Note that if the expression is part of conditional for a
900 ** LEFT JOIN, then we cannot determine at compile-time whether or not
901 ** is it true or false, so always return 0.
902 */
908 }
914 }
916 /*
917 ** Join two expressions using an AND operator. If either expression is
918 ** NULL, then just return the other expression.
919 **
920 ** If one side or the other of the AND is known to be false, then instead
921 ** of returning an AND expression, just return a constant expression with
922 ** a value of false.
923 */
937 }
938 }
940 /*
941 ** Construct a new expression node for a function with multiple
942 ** arguments.
943 */
952 }
958 }
960 /*
961 ** Assign a variable number to an expression that encodes a wildcard
962 ** in the original SQL statement.
963 **
964 ** Wildcards consisting of a single "?" are assigned the next sequential
965 ** variable number.
966 **
967 ** Wildcards of the form "?nnn" are assigned the number "nnn". We make
968 ** sure "nnn" is not too big to avoid a denial of service attack when
969 ** the SQL statement comes from an external source.
970 **
971 ** Wildcards of the form ":aaa", "@aaa", or "$aaa" are assigned the same number
972 ** as the previous instance of the same wildcard. Or if this is the first
973 ** instance of the wildcard, the next sequential variable number is
974 ** assigned.
975 */
979 ynVar x;
988 /* Wildcard of the form "?". Assign the next variable number */
994 /* Wildcard of the form "?nnn". Convert "nnn" to an integer and
995 ** use it as the variable number */
996 i64 i;
1003 }
1012 }
1019 }
1021 /* Wildcards like ":aaa", "$aaa" or "@aaa". Reuse the same variable
1022 ** number as the prior appearance of the same name, or if the name
1023 ** has never appeared before, reuse the same variable number
1024 */
1029 }
1030 }
1033 }
1034 }
1038 }
1039 }
1041 /*
1042 ** Recursively delete an expression tree.
1043 */
1046 /* Sanity check: Assert that the IntValue is non-negative if it exists */
1048 #ifdef SQLITE_DEBUG
1053 }
1054 #endif
1056 /* The Expr.x union is never used at the same time as Expr.pRight */
1065 }
1066 }
1070 }
1071 }
1074 }
1076 /*
1077 ** Return the number of bytes allocated for the expression structure
1078 ** passed as the first argument. This is always one of EXPR_FULLSIZE,
1079 ** EXPR_REDUCEDSIZE or EXPR_TOKENONLYSIZE.
1080 */
1085 }
1087 /*
1088 ** The dupedExpr*Size() routines each return the number of bytes required
1089 ** to store a copy of an expression or expression tree. They differ in
1090 ** how much of the tree is measured.
1091 **
1092 ** dupedExprStructSize() Size of only the Expr structure
1093 ** dupedExprNodeSize() Size of Expr + space for token
1094 ** dupedExprSize() Expr + token + subtree components
1095 **
1096 ***************************************************************************
1097 **
1098 ** The dupedExprStructSize() function returns two values OR-ed together:
1099 ** (1) the space required for a copy of the Expr structure only and
1100 ** (2) the EP_xxx flags that indicate what the structure size should be.
1101 ** The return values is always one of:
1102 **
1103 ** EXPR_FULLSIZE
1104 ** EXPR_REDUCEDSIZE | EP_Reduced
1105 ** EXPR_TOKENONLYSIZE | EP_TokenOnly
1106 **
1107 ** The size of the structure can be found by masking the return value
1108 ** of this routine with 0xfff. The flags can be found by masking the
1109 ** return value with EP_Reduced|EP_TokenOnly.
1110 **
1111 ** Note that with flags==EXPRDUP_REDUCE, this routines works on full-size
1112 ** (unreduced) Expr objects as they or originally constructed by the parser.
1113 ** During expression analysis, extra information is computed and moved into
1114 ** later parts of teh Expr object and that extra information might get chopped
1115 ** off if the expression is reduced. Note also that it does not work to
1116 ** make an EXPRDUP_REDUCE copy of a reduced expression. It is only legal
1117 ** to reduce a pristine expression tree from the parser. The implementation
1118 ** of dupedExprStructSize() contain multiple assert() statements that attempt
1119 ** to enforce this constraint.
1120 */
1138 }
1139 }
1141 }
1143 /*
1144 ** This function returns the space in bytes required to store the copy
1145 ** of the Expr structure and a copy of the Expr.u.zToken string (if that
1146 ** string is defined.)
1147 */
1152 }
1154 }
1156 /*
1157 ** Return the number of bytes required to create a duplicate of the
1158 ** expression passed as the first argument. The second argument is a
1159 ** mask containing EXPRDUP_XXX flags.
1160 **
1161 ** The value returned includes space to create a copy of the Expr struct
1162 ** itself and the buffer referred to by Expr.u.zToken, if any.
1163 **
1164 ** If the EXPRDUP_REDUCE flag is set, then the return value includes
1165 ** space to duplicate all Expr nodes in the tree formed by Expr.pLeft
1166 ** and Expr.pRight variables (but not for any structures pointed to or
1167 ** descended from the Expr.x.pList or Expr.x.pSelect variables).
1168 */
1175 }
1176 }
1178 }
1180 /*
1181 ** This function is similar to sqlite3ExprDup(), except that if pzBuffer
1182 ** is not NULL then *pzBuffer is assumed to point to a buffer large enough
1183 ** to store the copy of expression p, the copies of p->u.zToken
1184 ** (if applicable), and the copies of the p->pLeft and p->pRight expressions,
1185 ** if any. Before returning, *pzBuffer is set to the first byte past the
1186 ** portion of the buffer copied into by this function.
1187 */
1198 /* Figure out where to write the new Expr structure. */
1205 }
1209 /* Set nNewSize to the size allocated for the structure pointed to
1210 ** by pNew. This is either EXPR_FULLSIZE, EXPR_REDUCEDSIZE or
1211 ** EXPR_TOKENONLYSIZE. nToken is set to the number of bytes consumed
1212 ** by the copy of the p->u.zToken string (if any).
1213 */
1221 }
1230 }
1231 }
1233 /* Set the EP_Reduced, EP_TokenOnly, and EP_Static flags appropriately. */
1238 /* Copy the p->u.zToken string, if any. */
1242 }
1245 /* Fill in the pNew->x.pSelect or pNew->x.pList member. */
1250 }
1251 }
1253 /* Fill in pNew->pLeft and pNew->pRight. */
1261 }
1264 }
1273 }
1275 }
1276 }
1277 }
1279 }
1281 /*
1282 ** Create and return a deep copy of the object passed as the second
1283 ** argument. If an OOM condition is encountered, NULL is returned
1284 ** and the db->mallocFailed flag set.
1285 */
1286 #ifndef SQLITE_OMIT_CTE
1299 }
1300 }
1301 }
1303 }
1304 #else
1305 # define withDup(x,y) 0
1306 #endif
1308 /*
1309 ** The following group of routines make deep copies of expressions,
1310 ** expression lists, ID lists, and select statements. The copies can
1311 ** be deleted (by being passed to their respective ...Delete() routines)
1312 ** without effecting the originals.
1313 **
1314 ** The expression list, ID, and source lists return by sqlite3ExprListDup(),
1315 ** sqlite3IdListDup(), and sqlite3SrcListDup() can not be further expanded
1316 ** by subsequent calls to sqlite*ListAppend() routines.
1317 **
1318 ** Any tables that the SrcList might point to are not duplicated.
1319 **
1320 ** The flags parameter contains a combination of the EXPRDUP_XXX flags.
1321 ** If the EXPRDUP_REDUCE flag is set, then the structure returned is a
1322 ** truncated version of the usual Expr structure that will be stored as
1323 ** part of the in-memory representation of the database schema.
1324 */
1328 }
1348 ){
1359 }
1360 }
1368 }
1370 }
1372 /*
1373 ** If cursors, triggers, views and subqueries are all omitted from
1374 ** the build, then none of the following routines, except for
1375 ** sqlite3SelectDup(), can be called. sqlite3SelectDup() is sometimes
1376 ** called with a NULL argument.
1377 */
1378 #if !defined(SQLITE_OMIT_VIEW) || !defined(SQLITE_OMIT_TRIGGER) \
1379 || !defined(SQLITE_OMIT_SUBQUERY)
1404 }
1409 }
1413 }
1418 }
1420 }
1433 }
1434 /* Note that because the size of the allocation for p->a[] is not
1435 ** necessarily a power of two, sqlite3IdListAppend() may not be called
1436 ** on the duplicate created by this function. */
1442 }
1444 }
1476 }
1479 }
1480 #else
1484 }
1485 #endif
1488 /*
1489 ** Add a new element to the end of an expression list. If pList is
1490 ** initially NULL, then create a new expression list.
1491 **
1492 ** The pList argument must be either NULL or a pointer to an ExprList
1493 ** obtained from a prior call to sqlite3ExprListAppend(). This routine
1494 ** may not be used with an ExprList obtained from sqlite3ExprListDup().
1495 ** Reason: This routine assumes that the number of slots in pList->a[]
1496 ** is a power of two. That is true for sqlite3ExprListAppend() returns
1497 ** but is not necessarily true from the return value of sqlite3ExprListDup().
1498 **
1499 ** If a memory allocation error occurs, the entire list is freed and
1500 ** NULL is returned. If non-NULL is returned, then it is guaranteed
1501 ** that the new entry was successfully appended.
1502 */
1507 ){
1515 }
1523 }
1525 }
1533 no_mem:
1534 /* Avoid leaking memory if malloc has failed. */
1538 }
1540 /*
1541 ** pColumns and pExpr form a vector assignment which is part of the SET
1542 ** clause of an UPDATE statement. Like this:
1543 **
1544 ** (a,b,c) = (expr1,expr2,expr3)
1545 ** Or: (a,b,c) = (SELECT x,y,z FROM ....)
1546 **
1547 ** For each term of the vector assignment, append new entries to the
1548 ** expression list pList. In the case of a subquery on the RHS, append
1549 ** TK_SELECT_COLUMN expressions.
1550 */
1556 ){
1561 /* pColumns can only be NULL due to an OOM but an OOM will cause an
1562 ** exit prior to this routine being invoked */
1566 /* If the RHS is a vector, then we can immediately check to see that
1567 ** the size of the RHS and LHS match. But if the RHS is a SELECT,
1568 ** wildcards ("*") in the result set of the SELECT must be expanded before
1569 ** we can do the size check, so defer the size check until code generation.
1570 */
1575 }
1584 }
1585 }
1592 /* Store the SELECT statement in pRight so it will be deleted when
1593 ** sqlite3ExprListDelete() is called */
1597 /* Remember the size of the LHS in iTable so that we can check that
1598 ** the RHS and LHS sizes match during code generation. */
1600 }
1602 vector_append_error:
1606 }
1608 /*
1609 ** Set the sort order for the last element on the given ExprList.
1610 */
1618 }
1620 }
1622 /*
1623 ** Set the ExprList.a[].zName element of the most recently added item
1624 ** on the expression list.
1625 **
1626 ** pList might be NULL following an OOM error. But pName should never be
1627 ** NULL. If a memory allocation fails, the pParse->db->mallocFailed flag
1628 ** is set.
1629 */
1635 ){
1644 }
1645 }
1647 /*
1648 ** Set the ExprList.a[].zSpan element of the most recently added item
1649 ** on the expression list.
1650 **
1651 ** pList might be NULL following an OOM error. But pSpan should never be
1652 ** NULL. If a memory allocation fails, the pParse->db->mallocFailed flag
1653 ** is set.
1654 */
1660 ){
1668 }
1669 }
1671 /*
1672 ** If the expression list pEList contains more than iLimit elements,
1673 ** leave an error message in pParse.
1674 */
1679 ){
1685 }
1686 }
1688 /*
1689 ** Delete an entire expression list.
1690 */
1699 pItem++;
1702 }
1705 }
1707 /*
1708 ** Return the bitwise-OR of all Expr.flags fields in the given
1709 ** ExprList.
1710 */
1719 }
1721 }
1723 /*
1724 ** This is a SELECT-node callback for the expression walker that
1725 ** always "fails". By "fail" in this case, we mean set
1726 ** pWalker->eCode to zero and abort.
1727 **
1728 ** This callback is used by multiple expression walkers.
1729 */
1734 }
1736 /*
1737 ** If the input expression is an ID with the name "true" or "false"
1738 ** then convert it into an TK_TRUEFALSE term. Return non-zero if
1739 ** the conversion happened, and zero if the expression is unaltered.
1740 */
1745 ){
1748 }
1750 }
1752 /*
1753 ** The argument must be a TK_TRUEFALSE Expr node. Return 1 if it is TRUE
1754 ** and 0 if it is FALSE.
1755 */
1761 }
1764 /*
1765 ** These routines are Walker callbacks used to check expressions to
1766 ** see if they are "constant" for some definition of constant. The
1767 ** Walker.eCode value determines the type of "constant" we are looking
1768 ** for.
1769 **
1770 ** These callback routines are used to implement the following:
1771 **
1772 ** sqlite3ExprIsConstant() pWalker->eCode==1
1773 ** sqlite3ExprIsConstantNotJoin() pWalker->eCode==2
1774 ** sqlite3ExprIsTableConstant() pWalker->eCode==3
1775 ** sqlite3ExprIsConstantOrFunction() pWalker->eCode==4 or 5
1776 **
1777 ** In all cases, the callbacks set Walker.eCode=0 and abort if the expression
1778 ** is found to not be a constant.
1779 **
1780 ** The sqlite3ExprIsConstantOrFunction() is used for evaluating expressions
1781 ** in a CREATE TABLE statement. The Walker.eCode value is 5 when parsing
1782 ** an existing schema and 4 when processing a new statement. A bound
1783 ** parameter raises an error for new statements, but is silently converted
1784 ** to NULL for existing schemas. This allows sqlite_master tables that
1785 ** contain a bound parameter because they were generated by older versions
1786 ** of SQLite to be parsed by newer versions of SQLite without raising a
1787 ** malformed schema error.
1788 */
1791 /* If pWalker->eCode is 2 then any term of the expression that comes from
1792 ** the ON or USING clauses of a left join disqualifies the expression
1793 ** from being considered constant. */
1797 }
1800 /* Consider functions to be constant if all their arguments are constant
1801 ** and either pWalker->eCode==4 or 5 or the function has the
1802 ** SQLITE_FUNC_CONST flag. */
1809 }
1811 /* Convert "true" or "false" in a DEFAULT clause into the
1812 ** appropriate TK_TRUEFALSE operator */
1815 }
1816 /* Fall thru */
1826 }
1827 /* Fall through */
1836 /* Silently convert bound parameters that appear inside of CREATE
1837 ** statements into a NULL when parsing the CREATE statement text out
1838 ** of the sqlite_master table */
1841 /* A bound parameter in a CREATE statement that originates from
1842 ** sqlite3_prepare() causes an error */
1845 }
1846 /* Fall through */
1851 }
1852 }
1854 Walker w;
1858 #ifdef SQLITE_DEBUG
1860 #endif
1864 }
1866 /*
1867 ** Walk an expression tree. Return non-zero if the expression is constant
1868 ** and 0 if it involves variables or function calls.
1869 **
1870 ** For the purposes of this function, a double-quoted string (ex: "abc")
1871 ** is considered a variable but a single-quoted string (ex: 'abc') is
1872 ** a constant.
1873 */
1876 }
1878 /*
1879 ** Walk an expression tree. Return non-zero if the expression is constant
1880 ** that does no originate from the ON or USING clauses of a join.
1881 ** Return 0 if it involves variables or function calls or terms from
1882 ** an ON or USING clause.
1883 */
1886 }
1888 /*
1889 ** Walk an expression tree. Return non-zero if the expression is constant
1890 ** for any single row of the table with cursor iCur. In other words, the
1891 ** expression must not refer to any non-deterministic function nor any
1892 ** table other than iCur.
1893 */
1896 }
1899 /*
1900 ** sqlite3WalkExpr() callback used by sqlite3ExprIsConstantOrGroupBy().
1901 */
1906 /* Check if pExpr is identical to any GROUP BY term. If so, consider
1907 ** it constant. */
1914 }
1915 }
1916 }
1918 /* Check if pExpr is a sub-select. If so, consider it variable. */
1922 }
1925 }
1927 /*
1928 ** Walk the expression tree passed as the first argument. Return non-zero
1929 ** if the expression consists entirely of constants or copies of terms
1930 ** in pGroupBy that sort with the BINARY collation sequence.
1931 **
1932 ** This routine is used to determine if a term of the HAVING clause can
1933 ** be promoted into the WHERE clause. In order for such a promotion to work,
1934 ** the value of the HAVING clause term must be the same for all members of
1935 ** a "group". The requirement that the GROUP BY term must be BINARY
1936 ** assumes that no other collating sequence will have a finer-grained
1937 ** grouping than binary. In other words (A=B COLLATE binary) implies
1938 ** A=B in every other collating sequence. The requirement that the
1939 ** GROUP BY be BINARY is stricter than necessary. It would also work
1940 ** to promote HAVING clauses that use the same alternative collating
1941 ** sequence as the GROUP BY term, but that is much harder to check,
1942 ** alternative collating sequences are uncommon, and this is only an
1943 ** optimization, so we take the easy way out and simply require the
1944 ** GROUP BY to use the BINARY collating sequence.
1945 */
1947 Walker w;
1955 }
1957 /*
1958 ** Walk an expression tree. Return non-zero if the expression is constant
1959 ** or a function call with constant arguments. Return and 0 if there
1960 ** are any variables.
1961 **
1962 ** For the purposes of this function, a double-quoted string (ex: "abc")
1963 ** is considered a variable but a single-quoted string (ex: 'abc') is
1964 ** a constant.
1965 */
1969 }
1971 #ifdef SQLITE_ENABLE_CURSOR_HINTS
1972 /*
1973 ** Walk an expression tree. Return 1 if the expression contains a
1974 ** subquery of some kind. Return 0 if there are no subqueries.
1975 */
1977 Walker w;
1981 #ifdef SQLITE_DEBUG
1983 #endif
1986 }
1987 #endif
1989 /*
1990 ** If the expression p codes a constant integer that is small enough
1991 ** to fit in a 32-bit integer, return 1 and put the value of the integer
1992 ** in *pValue. If the expression is not an integer or if it is too big
1993 ** to fit in a signed 32-bit integer, return 0 and leave *pValue unchanged.
1994 */
1999 /* If an expression is an integer literal that fits in a signed 32-bit
2000 ** integer, then the EP_IntValue flag will have already been set */
2007 }
2012 }
2019 }
2021 }
2023 }
2025 }
2027 /*
2028 ** Return FALSE if there is no chance that the expression can be NULL.
2029 **
2030 ** If the expression might be NULL or if the expression is too complex
2031 ** to tell return TRUE.
2032 **
2033 ** This routine is used as an optimization, to skip OP_IsNull opcodes
2034 ** when we know that a value cannot be NULL. Hence, a false positive
2035 ** (returning TRUE when in fact the expression can never be NULL) might
2036 ** be a small performance hit but is otherwise harmless. On the other
2037 ** hand, a false negative (returning FALSE when the result could be NULL)
2038 ** will likely result in an incorrect answer. So when in doubt, return
2039 ** TRUE.
2040 */
2042 u8 op;
2058 }
2059 }
2061 /*
2062 ** Return TRUE if the given expression is a constant which would be
2063 ** unchanged by OP_Affinity with the affinity given in the second
2064 ** argument.
2065 **
2066 ** This routine is used to determine if the OP_Affinity operation
2067 ** can be omitted. When in doubt return FALSE. A false negative
2068 ** is harmless. A false positive, however, can result in the wrong
2069 ** answer.
2070 */
2072 u8 op;
2080 }
2083 }
2086 }
2089 }
2094 }
2097 }
2098 }
2099 }
2101 /*
2102 ** Return TRUE if the given string is a row-id column name.
2103 */
2109 }
2111 /*
2112 ** pX is the RHS of an IN operator. If pX is a SELECT statement
2113 ** that can be simplified to a direct table access, then return
2114 ** a pointer to the SELECT statement. If pX is not a SELECT statement,
2115 ** or if the SELECT statement needs to be manifested into a transient
2116 ** table, then return NULL.
2117 */
2118 #ifndef SQLITE_OMIT_SUBQUERY
2133 }
2147 /* All SELECT results must be columns. */
2152 }
2154 }
2157 #ifndef SQLITE_OMIT_SUBQUERY
2158 /*
2159 ** Generate code that checks the left-most column of index table iCur to see if
2160 ** it contains any NULL entries. Cause the register at regHasNull to be set
2161 ** to a non-NULL value if iCur contains no NULLs. Cause register regHasNull
2162 ** to be set to NULL if iCur contains one or more NULL values.
2163 */
2172 }
2173 #endif
2176 #ifndef SQLITE_OMIT_SUBQUERY
2177 /*
2178 ** The argument is an IN operator with a list (not a subquery) on the
2179 ** right-hand side. Return TRUE if that list is constant.
2180 */
2190 }
2191 #endif
2193 /*
2194 ** This function is used by the implementation of the IN (...) operator.
2195 ** The pX parameter is the expression on the RHS of the IN operator, which
2196 ** might be either a list of expressions or a subquery.
2197 **
2198 ** The job of this routine is to find or create a b-tree object that can
2199 ** be used either to test for membership in the RHS set or to iterate through
2200 ** all members of the RHS set, skipping duplicates.
2201 **
2202 ** A cursor is opened on the b-tree object that is the RHS of the IN operator
2203 ** and pX->iTable is set to the index of that cursor.
2204 **
2205 ** The returned value of this function indicates the b-tree type, as follows:
2206 **
2207 ** IN_INDEX_ROWID - The cursor was opened on a database table.
2208 ** IN_INDEX_INDEX_ASC - The cursor was opened on an ascending index.
2209 ** IN_INDEX_INDEX_DESC - The cursor was opened on a descending index.
2210 ** IN_INDEX_EPH - The cursor was opened on a specially created and
2211 ** populated epheremal table.
2212 ** IN_INDEX_NOOP - No cursor was allocated. The IN operator must be
2213 ** implemented as a sequence of comparisons.
2214 **
2215 ** An existing b-tree might be used if the RHS expression pX is a simple
2216 ** subquery such as:
2217 **
2218 ** SELECT <column1>, <column2>... FROM <table>
2219 **
2220 ** If the RHS of the IN operator is a list or a more complex subquery, then
2221 ** an ephemeral table might need to be generated from the RHS and then
2222 ** pX->iTable made to point to the ephemeral table instead of an
2223 ** existing table.
2224 **
2225 ** The inFlags parameter must contain, at a minimum, one of the bits
2226 ** IN_INDEX_MEMBERSHIP or IN_INDEX_LOOP but not both. If inFlags contains
2227 ** IN_INDEX_MEMBERSHIP, then the generated table will be used for a fast
2228 ** membership test. When the IN_INDEX_LOOP bit is set, the IN index will
2229 ** be used to loop over all values of the RHS of the IN operator.
2230 **
2231 ** When IN_INDEX_LOOP is used (and the b-tree will be used to iterate
2232 ** through the set members) then the b-tree must not contain duplicates.
2233 ** An epheremal table will be created unless the selected columns are guaranteed
2234 ** to be unique - either because it is an INTEGER PRIMARY KEY or due to
2235 ** a UNIQUE constraint or index.
2236 **
2237 ** When IN_INDEX_MEMBERSHIP is used (and the b-tree will be used
2238 ** for fast set membership tests) then an epheremal table must
2239 ** be used unless <columns> is a single INTEGER PRIMARY KEY column or an
2240 ** index can be found with the specified <columns> as its left-most.
2241 **
2242 ** If the IN_INDEX_NOOP_OK and IN_INDEX_MEMBERSHIP are both set and
2243 ** if the RHS of the IN operator is a list (not a subquery) then this
2244 ** routine might decide that creating an ephemeral b-tree for membership
2245 ** testing is too expensive and return IN_INDEX_NOOP. In that case, the
2246 ** calling routine should implement the IN operator using a sequence
2247 ** of Eq or Ne comparison operations.
2248 **
2249 ** When the b-tree is being used for membership tests, the calling function
2250 ** might need to know whether or not the RHS side of the IN operator
2251 ** contains a NULL. If prRhsHasNull is not a NULL pointer and
2252 ** if there is any chance that the (...) might contain a NULL value at
2253 ** runtime, then a register is allocated and the register number written
2254 ** to *prRhsHasNull. If there is no chance that the (...) contains a
2255 ** NULL value, then *prRhsHasNull is left unchanged.
2256 **
2257 ** If a register is allocated and its location stored in *prRhsHasNull, then
2258 ** the value in that register will be NULL if the b-tree contains one or more
2259 ** NULL values, and it will be some non-NULL value if the b-tree contains no
2260 ** NULL values.
2261 **
2262 ** If the aiMap parameter is not NULL, it must point to an array containing
2263 ** one element for each column returned by the SELECT statement on the RHS
2264 ** of the IN(...) operator. The i'th entry of the array is populated with the
2265 ** offset of the index column that matches the i'th column returned by the
2266 ** SELECT. For example, if the expression and selected index are:
2267 **
2268 ** (?,?,?) IN (SELECT a, b, c FROM t1)
2269 ** CREATE INDEX i1 ON t1(b, c, a);
2270 **
2271 ** then aiMap[] is populated with {2, 0, 1}.
2272 */
2273 #ifndef SQLITE_OMIT_SUBQUERY
2280 ){
2290 /* If the RHS of this IN(...) operator is a SELECT, and if it matters
2291 ** whether or not the SELECT result contains NULL values, check whether
2292 ** or not NULL is actually possible (it may not be, for example, due
2293 ** to NOT NULL constraints in the schema). If no NULL values are possible,
2294 ** set prRhsHasNull to 0 before continuing. */
2300 }
2303 }
2304 }
2306 /* Check to see if an existing table or index can be used to
2307 ** satisfy the query. This is preferable to generating a new
2308 ** ephemeral table. */
2321 /* Code an OP_Transaction and OP_TableLock for <table>. */
2328 /* The "x IN (SELECT rowid FROM table)" case */
2341 /* Check that the affinity that will be used to perform each
2342 ** comparison is the same as the affinity of each column in table
2343 ** on the RHS of the IN operator. If it not, it is not possible to
2344 ** use any index of the RHS table. */
2356 /* sqlite3CompareAffinity() only returns TEXT if one side or the
2357 ** other has no affinity and the other side is TEXT. Hence,
2358 ** the only way for cmpaff to be TEXT is for idxaff to be TEXT
2359 ** and for the term on the LHS of the IN to have no affinity. */
2364 }
2365 }
2368 /* Search for an existing index that will work for this IN operator */
2373 /* Maximum nColumn is BMS-2, not BMS-1, so that we can compute
2374 ** BITMASK(nExpr) without overflowing */
2381 ){
2383 }
2384 }
2399 }
2401 }
2407 }
2411 /* If we reach this point, that means the index pIdx is usable */
2413 #ifndef SQLITE_OMIT_EXPLAIN
2416 P4_DYNAMIC);
2417 #endif
2425 #ifdef SQLITE_ENABLE_COLUMN_USED_MASK
2429 #endif
2433 }
2434 }
2436 }
2442 /* If no preexisting index is available for the IN clause
2443 ** and IN_INDEX_NOOP is an allowed reply
2444 ** and the RHS of the IN operator is a list, not a subquery
2445 ** and the RHS is not constant or has two or fewer terms,
2446 ** then it is not worth creating an ephemeral table to evaluate
2447 ** the IN operator so return IN_INDEX_NOOP.
2448 */
2453 ){
2455 }
2458 /* Could not find an existing table or index to use as the RHS b-tree.
2459 ** We will have to generate an ephemeral table to do the job.
2460 */
2468 }
2471 }
2476 }
2482 }
2484 }
2485 #endif
2487 #ifndef SQLITE_OMIT_SUBQUERY
2488 /*
2489 ** Argument pExpr is an (?, ?...) IN(...) expression. This
2490 ** function allocates and returns a nul-terminated string containing
2491 ** the affinities to be used for each column of the comparison.
2492 **
2493 ** It is the responsibility of the caller to ensure that the returned
2494 ** string is eventually freed using sqlite3DbFree().
2495 */
2513 }
2514 }
2516 }
2518 }
2519 #endif
2521 #ifndef SQLITE_OMIT_SUBQUERY
2522 /*
2523 ** Load the Parse object passed as the first argument with an error
2524 ** message of the form:
2525 **
2526 ** "sub-select returns N columns - expected M"
2527 */
2531 }
2532 #endif
2534 /*
2535 ** Expression pExpr is a vector that has been used in a context where
2536 ** it is not permitted. If pExpr is a sub-select vector, this routine
2537 ** loads the Parse object with a message of the form:
2538 **
2539 ** "sub-select returns N columns - expected 1"
2540 **
2541 ** Or, if it is a regular scalar vector:
2542 **
2543 ** "row value misused"
2544 */
2546 #ifndef SQLITE_OMIT_SUBQUERY
2550 #endif
2551 {
2553 }
2554 }
2556 /*
2557 ** Generate code for scalar subqueries used as a subquery expression, EXISTS,
2558 ** or IN operators. Examples:
2559 **
2560 ** (SELECT a FROM b) -- subquery
2561 ** EXISTS (SELECT a FROM b) -- EXISTS subquery
2562 ** x IN (4,5,11) -- IN operator with list on right-hand side
2563 ** x IN (SELECT a FROM b) -- IN operator with subquery on the right
2564 **
2565 ** The pExpr parameter describes the expression that contains the IN
2566 ** operator or subquery.
2567 **
2568 ** If parameter isRowid is non-zero, then expression pExpr is guaranteed
2569 ** to be of the form "<rowid> IN (?, ?, ?)", where <rowid> is a reference
2570 ** to some integer key column of a table B-Tree. In this case, use an
2571 ** intkey B-Tree to store the set of IN(...) values instead of the usual
2572 ** (slower) variable length keys B-Tree.
2573 **
2574 ** If rMayHaveNull is non-zero, that means that the operation is an IN
2575 ** (not a SELECT or EXISTS) and that the RHS might contains NULLs.
2576 ** All this routine does is initialize the register given by rMayHaveNull
2577 ** to NULL. Calling routines will take care of changing this register
2578 ** value to non-NULL if the RHS is NULL-free.
2579 **
2580 ** For a SELECT or EXISTS operator, return the register that holds the
2581 ** result. For a multi-column SELECT, the result is stored in a contiguous
2582 ** array of registers and the return value is the register of the left-most
2583 ** result column. Return 0 for IN operators or if an error occurs.
2584 */
2585 #ifndef SQLITE_OMIT_SUBQUERY
2591 ){
2598 /* The evaluation of the IN/EXISTS/SELECT must be repeated every time it
2599 ** is encountered if any of the following is true:
2600 **
2601 ** * The right-hand side is a correlated subquery
2602 ** * The right-hand side is an expression list containing variables
2603 ** * We are inside a trigger
2604 **
2605 ** If all of the above are false, then we can run this code just once
2606 ** save the results, and reuse the same result on subsequent invocations.
2607 */
2610 }
2622 /* Whether this is an 'x IN(SELECT...)' or an 'x IN(<exprlist>)'
2623 ** expression it is handled the same way. An ephemeral table is
2624 ** filled with index keys representing the results from the
2625 ** SELECT or the <exprlist>.
2626 **
2627 ** If the 'x' expression is a column value, or the SELECT...
2628 ** statement returns a column value, then the affinity of that
2629 ** column is used to build the index keys. If both 'x' and the
2630 ** SELECT... statement are columns, then numeric affinity is used
2631 ** if either column has NUMERIC or INTEGER affinity. If neither
2632 ** 'x' nor the SELECT... statement are columns, then numeric affinity
2633 ** is used.
2634 */
2641 /* Case 1: expr IN (SELECT ...)
2642 **
2643 ** Generate code to write the results of the select into the temporary
2644 ** table allocated and opened above.
2645 */
2649 #ifndef SQLITE_OMIT_EXPLAIN
2653 pParse->iNextSelectId
2654 );
2656 P4_DYNAMIC);
2657 }
2658 #endif
2661 /* If the LHS and RHS of the IN operator do not match, that
2662 ** error will have been caught long before we reach this point. */
2664 SelectDest dest;
2675 }
2685 );
2686 }
2687 }
2689 /* Case 2: expr IN (exprlist)
2690 **
2691 ** For each expression, build an index key from the evaluation and
2692 ** store it in the temporary table. If <expr> is a column, then use
2693 ** that columns affinity when building index keys. If <expr> is not
2694 ** a column, use numeric affinity.
2695 */
2704 }
2708 }
2710 /* Loop through each expression in <exprlist>. */
2718 /* If the expression is not constant then we will need to
2719 ** disable the test that was generated above that makes sure
2720 ** this code only executes once. Because for a non-constant
2721 ** expression we need to rerun this code each time.
2722 */
2726 }
2728 /* Evaluate the expression and insert it into the temp table */
2742 }
2743 }
2744 }
2747 }
2750 }
2752 }
2757 /* Case 3: (SELECT ... FROM ...)
2758 ** or: EXISTS(SELECT ... FROM ...)
2759 **
2760 ** For a SELECT, generate code to put the values for all columns of
2761 ** the first row into an array of registers and return the index of
2762 ** the first register.
2763 **
2764 ** If this is an EXISTS, write an integer 0 (not exists) or 1 (exists)
2765 ** into a register and return that register number.
2766 **
2767 ** In both cases, the query is augmented with "LIMIT 1". Any
2768 ** preexisting limit is discarded in place of the new LIMIT 1.
2769 */
2780 #ifndef SQLITE_OMIT_EXPLAIN
2784 pParse->iNextSelectId
2785 );
2787 P4_DYNAMIC);
2788 }
2789 #endif
2805 }
2812 }
2816 }
2820 }
2821 }
2825 }
2829 }
2833 }
2836 #ifndef SQLITE_OMIT_SUBQUERY
2837 /*
2838 ** Expr pIn is an IN(...) expression. This function checks that the
2839 ** sub-select on the RHS of the IN() operator has the same number of
2840 ** columns as the vector on the LHS. Or, if the RHS of the IN() is not
2841 ** a sub-query, that the LHS is a vector of size 1.
2842 */
2849 }
2853 }
2855 }
2856 #endif
2858 #ifndef SQLITE_OMIT_SUBQUERY
2859 /*
2860 ** Generate code for an IN expression.
2861 **
2862 ** x IN (SELECT ...)
2863 ** x IN (value, value, ...)
2864 **
2865 ** The left-hand side (LHS) is a scalar or vector expression. The
2866 ** right-hand side (RHS) is an array of zero or more scalar values, or a
2867 ** subquery. If the RHS is a subquery, the number of result columns must
2868 ** match the number of columns in the vector on the LHS. If the RHS is
2869 ** a list of values, the LHS must be a scalar.
2870 **
2871 ** The IN operator is true if the LHS value is contained within the RHS.
2872 ** The result is false if the LHS is definitely not in the RHS. The
2873 ** result is NULL if the presence of the LHS in the RHS cannot be
2874 ** determined due to NULLs.
2875 **
2876 ** This routine generates code that jumps to destIfFalse if the LHS is not
2877 ** contained within the RHS. If due to NULLs we cannot determine if the LHS
2878 ** is contained in the RHS then jump to destIfNull. If the LHS is contained
2879 ** within the RHS then fall through.
2880 **
2881 ** See the separate in-operator.md documentation file in the canonical
2882 ** SQLite source tree for additional information.
2883 */
2889 ){
2913 );
2916 /* Attempt to compute the RHS. After this step, if anything other than
2917 ** IN_INDEX_NOOP is returned, the table opened ith cursor pExpr->iTable
2918 ** contains the values that make up the RHS. If IN_INDEX_NOOP is returned,
2919 ** the RHS has not yet been coded. */
2929 );
2930 #ifdef SQLITE_DEBUG
2931 /* Confirm that aiMap[] contains nVector integer values between 0 and
2932 ** nVector-1. */
2937 }
2938 #endif
2940 /* Code the LHS, the <expr> from "<expr> IN (...)". If the LHS is a
2941 ** vector, then it is stored in an array of nVector registers starting
2942 ** at r1.
2943 **
2944 ** sqlite3FindInIndex() might have reordered the fields of the LHS vector
2945 ** so that the fields are in the same order as an existing index. The
2946 ** aiMap[] array contains a mapping from the original LHS field order to
2947 ** the field order that matches the RHS index.
2948 */
2953 /* LHS fields are not reordered */
2956 /* Need to reorder the LHS fields according to aiMap */
2960 }
2961 }
2963 /* If sqlite3FindInIndex() did not find or create an index that is
2964 ** suitable for evaluating the IN operator, then evaluate using a
2965 ** sequence of comparisons.
2966 **
2967 ** This is step (1) in the in-operator.md optimized algorithm.
2968 */
2980 }
2985 }
2997 }
2999 }
3003 }
3007 }
3009 /* Step 2: Check to see if the LHS contains any NULL columns. If the
3010 ** LHS does contain NULLs then the result must be either FALSE or NULL.
3011 ** We will then skip the binary search of the RHS.
3012 */
3017 }
3023 }
3024 }
3026 /* Step 3. The LHS is now known to be non-NULL. Do the binary search
3027 ** of the RHS using the LHS as a probe. If found, the result is
3028 ** true.
3029 */
3031 /* In this case, the RHS is the ROWID of table b-tree and so we also
3032 ** know that the RHS is non-NULL. Hence, we combine steps 3 and 4
3033 ** into a single opcode. */
3040 /* Combine Step 3 and Step 5 into a single opcode */
3044 }
3045 /* Ordinary Step 3, for the case where FALSE and NULL are distinct */
3048 }
3050 /* Step 4. If the RHS is known to be non-NULL and we did not find
3051 ** an match on the search above, then the result must be FALSE.
3052 */
3056 }
3058 /* Step 5. If we do not care about the difference between NULL and
3059 ** FALSE, then just return false.
3060 */
3063 /* Step 6: Loop through rows of the RHS. Compare each row to the LHS.
3064 ** If any comparison is NULL, then the result is NULL. If all
3065 ** comparisons are FALSE then the final result is FALSE.
3066 **
3067 ** For a scalar LHS, it is sufficient to check just the first row
3068 ** of the RHS.
3069 */
3076 /* For nVector==1, combine steps 6 and 7 by immediately returning
3077 ** FALSE if the first comparison is not NULL */
3079 }
3091 }
3098 /* Step 7: If we reach this point, we know that the result must
3099 ** be false. */
3101 }
3103 /* Jumps here in order to return true. */
3106 sqlite3ExprCodeIN_finished:
3110 sqlite3ExprCodeIN_oom_error:
3113 }
3116 #ifndef SQLITE_OMIT_FLOATING_POINT
3117 /*
3118 ** Generate an instruction that will put the floating point
3119 ** value described by z[0..n-1] into register iMem.
3120 **
3121 ** The z[] string will probably not be zero-terminated. But the
3122 ** z[n] character is guaranteed to be something that does not look
3123 ** like the continuation of the number.
3124 */
3132 }
3133 }
3134 #endif
3137 /*
3138 ** Generate an instruction that will put the integer describe by
3139 ** text z[0..n-1] into register iMem.
3140 **
3141 ** Expr.u.zToken is always UTF8 and zero-terminated.
3142 */
3152 i64 value;
3157 #ifdef SQLITE_OMIT_FLOATING_POINT
3159 #else
3160 #ifndef SQLITE_OMIT_HEX_INTEGER
3164 #endif
3165 {
3167 }
3168 #endif
3172 }
3173 }
3174 }
3176 /*
3177 ** Erase column-cache entry number i
3178 */
3183 }
3184 }
3188 }
3189 }
3192 /*
3193 ** Record in the column cache that a particular column from a
3194 ** particular table is stored in a particular register.
3195 */
3202 /* Unless an error has occurred, register numbers are always positive. */
3206 /* The SQLITE_ColumnCache flag disables the column cache. This is used
3207 ** for testing only - to verify that SQLite always gets the same answer
3208 ** with and without the column cache.
3209 */
3212 /* First replace any existing entry.
3213 **
3214 ** Actually, the way the column cache is currently used, we are guaranteed
3215 ** that the object will never already be in cache. Verify this guarantee.
3216 */
3217 #ifndef NDEBUG
3220 }
3221 #endif
3223 /* If the cache is already full, delete the least recently used entry */
3231 }
3232 }
3236 }
3238 /* Add the new entry to the end of the cache */
3245 }
3247 /*
3248 ** Indicate that registers between iReg..iReg+nReg-1 are being overwritten.
3249 ** Purge the range of registers from the column cache.
3250 */
3258 i++;
3259 }
3260 }
3261 }
3263 /*
3264 ** Remember the current column cache context. Any new entries added
3265 ** added to the column cache after this call are removed when the
3266 ** corresponding pop occurs.
3267 */
3270 #ifdef SQLITE_DEBUG
3273 }
3274 #endif
3275 }
3277 /*
3278 ** Remove from the column cache any entries that were added since the
3279 ** the previous sqlite3ExprCachePush operation. In other words, restore
3280 ** the cache to the state it was in prior the most recent Push.
3281 */
3286 #ifdef SQLITE_DEBUG
3289 }
3290 #endif
3295 i++;
3296 }
3297 }
3298 }
3300 /*
3301 ** When a cached column is reused, make sure that its register is
3302 ** no longer available as a temp register. ticket #3879: that same
3303 ** register might be in the cache in multiple places, so be sure to
3304 ** get them all.
3305 */
3312 }
3313 }
3314 }
3316 /* Generate code that will load into register regOut a value that is
3317 ** appropriate for the iIdxCol-th column of index pIdx.
3318 */
3325 ){
3336 }
3337 }
3339 /*
3340 ** Generate code to extract the value of the iCol-th column of a table.
3341 */
3348 ){
3352 }
3360 }
3362 }
3365 }
3366 }
3368 /*
3369 ** Generate code that will extract the iColumn-th column from
3370 ** table pTab and store the column value in a register.
3371 **
3372 ** An effort is made to store the column value in register iReg. This
3373 ** is not garanteeed for GetColumn() - the result can be stored in
3374 ** any register. But the result is guaranteed to land in register iReg
3375 ** for GetColumnToReg().
3376 **
3377 ** There must be an open cursor to pTab in iTable when this routine
3378 ** is called. If iColumn<0 then code is generated that extracts the rowid.
3379 */
3386 u8 p5 /* P5 value for OP_Column + FLAGS */
3387 ){
3397 }
3398 }
3405 }
3407 }
3414 ){
3417 }
3420 /*
3421 ** Clear all column cache entries.
3422 */
3426 #ifdef SQLITE_DEBUG
3429 }
3430 #endif
3434 ){
3436 }
3437 }
3439 }
3441 /*
3442 ** Record the fact that an affinity change has occurred on iCount
3443 ** registers starting with iStart.
3444 */
3447 }
3449 /*
3450 ** Generate code to move content from registers iFrom...iFrom+nReg-1
3451 ** over to iTo..iTo+nReg-1. Keep the column cache up-to-date.
3452 */
3457 }
3459 #if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
3460 /*
3461 ** Return true if any register in the range iFrom..iTo (inclusive)
3462 ** is used as part of the column cache.
3463 **
3464 ** This routine is used within assert() and testcase() macros only
3465 ** and does not appear in a normal build.
3466 */
3473 }
3475 }
3479 /*
3480 ** Convert a scalar expression node to a TK_REGISTER referencing
3481 ** register iReg. The caller must ensure that iReg already contains
3482 ** the correct value for the expression.
3483 */
3489 }
3491 /*
3492 ** Evaluate an expression (either a vector or a scalar expression) and store
3493 ** the result in continguous temporary registers. Return the index of
3494 ** the first register used to store the result.
3495 **
3496 ** If the returned result register is a temporary scalar, then also write
3497 ** that register number into *piFreeable. If the returned result register
3498 ** is not a temporary or if the expression is a vector set *piFreeable
3499 ** to 0.
3500 */
3509 #if SQLITE_OMIT_SUBQUERY
3511 #else
3513 #endif
3520 }
3521 }
3522 }
3524 }
3527 /*
3528 ** Generate code into the current Vdbe to evaluate the given
3529 ** expression. Attempt to store the results in register "target".
3530 ** Return the register where results are stored.
3531 **
3532 ** With this routine, there is no guarantee that results will
3533 ** be stored in target. The result might be stored in some other
3534 ** register if it is convenient to do so. The calling function
3535 ** must check the return code and move the results to the desired
3536 ** register.
3537 */
3552 }
3554 expr_code_doover:
3559 }
3571 }
3572 /* Otherwise, fall thru into the TK_COLUMN case */
3573 }
3578 /* Generating CHECK constraints or inserting into partial index */
3581 /* Coding an expression that is part of an index where column names
3582 ** in the index refer to the table to which the index belongs */
3584 }
3585 }
3589 }
3593 }
3597 }
3598 #ifndef SQLITE_OMIT_FLOATING_POINT
3603 }
3604 #endif
3609 }
3613 }
3614 #ifndef SQLITE_OMIT_BLOB_LITERAL
3628 }
3629 #endif
3640 }
3642 }
3645 }
3646 #ifndef SQLITE_OMIT_CAST
3648 /* Expressions of the form: CAST(pLeft AS token) */
3653 }
3659 }
3665 /* fall-through */
3688 }
3690 }
3720 }
3727 #ifndef SQLITE_OMIT_FLOATING_POINT
3732 #endif
3741 }
3743 }
3752 }
3764 }
3779 }
3787 }
3789 }
3802 /* SQL functions can be expensive. So try to move constant functions
3803 ** out of the inner loop, even if that means an extra OP_Copy. */
3805 }
3811 }
3816 #ifdef SQLITE_ENABLE_UNKNOWN_SQL_FUNCTION
3819 }
3820 #endif
3824 }
3826 /* Attempt a direct implementation of the built-in COALESCE() and
3827 ** IFNULL() functions. This avoids unnecessary evaluation of
3828 ** arguments past the first non-NULL argument.
3829 */
3841 }
3844 }
3846 /* The UNLIKELY() function is a no-op. The result is the value
3847 ** of the first argument.
3848 */
3852 }
3854 #ifdef SQLITE_DEBUG
3855 /* The AFFINITY() function evaluates to a string that describes
3856 ** the type affinity of the argument. This is used for testing of
3857 ** the SQLite type logic.
3858 */
3867 }
3868 #endif
3874 }
3877 }
3878 }
3885 }
3887 /* For length() and typeof() functions with a column argument,
3888 ** set the P5 parameter to the OP_Column opcode to OPFLAG_LENGTHARG
3889 ** or OPFLAG_TYPEOFARG respectively, to avoid unnecessary data
3890 ** loading.
3891 */
3893 u8 exprOp;
3903 }
3904 }
3912 }
3913 #ifndef SQLITE_OMIT_VIRTUALTABLE
3914 /* Possibly overload the function if the first argument is
3915 ** a virtual table column.
3916 **
3917 ** For infix functions (LIKE, GLOB, REGEXP, and MATCH) use the
3918 ** second argument, not the first, as the argument to test to
3919 ** see if it is a column in a virtual table. This is done because
3920 ** the left operand of infix functions (the operand we want to
3921 ** control overloading) ends up as the second argument to the
3922 ** function. The expression "A glob B" is equivalent to
3923 ** "glob(B,A). We want to use the A in "A glob B" to test
3924 ** for function overloading. But we use the B term in "glob(B,A)".
3925 */
3930 }
3931 #endif
3935 }
3936 #ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC
3943 }
3945 #endif
3946 {
3950 }
3953 }
3955 }
3956 #ifndef SQLITE_OMIT_SUBQUERY
3966 }
3968 }
3973 }
3977 ){
3980 }
3982 }
3993 }
3997 /*
3998 ** x BETWEEN y AND z
3999 **
4000 ** This is equivalent to
4001 **
4002 ** x>=y AND x<=z
4003 **
4004 ** X is stored in pExpr->pLeft.
4005 ** Y is stored in pExpr->pList->a[0].pExpr.
4006 ** Z is stored in pExpr->pList->a[1].pExpr.
4007 */
4011 }
4017 }
4020 /* If the opcode is TK_TRIGGER, then the expression is a reference
4021 ** to a column in the new.* or old.* pseudo-tables available to
4022 ** trigger programs. In this case Expr.iTable is set to 1 for the
4023 ** new.* pseudo-table, or 0 for the old.* pseudo-table. Expr.iColumn
4024 ** is set to the column of the pseudo-table to read, or to -1 to
4025 ** read the rowid field.
4026 **
4027 ** The expression is implemented using an OP_Param opcode. The p1
4028 ** parameter is set to 0 for an old.rowid reference, or to (i+1)
4029 ** to reference another column of the old.* pseudo-table, where
4030 ** i is the index of the column. For a new.rowid reference, p1 is
4031 ** set to (n+1), where n is the number of columns in each pseudo-table.
4032 ** For a reference to any other column in the new.* pseudo-table, p1
4033 ** is set to (n+2+i), where n and i are as defined previously. For
4034 ** example, if the table on which triggers are being fired is
4035 ** declared as:
4036 **
4037 ** CREATE TABLE t1(a, b);
4038 **
4039 ** Then p1 is interpreted as follows:
4040 **
4041 ** p1==0 -> old.rowid p1==3 -> new.rowid
4042 ** p1==1 -> old.a p1==4 -> new.a
4043 ** p1==2 -> old.b p1==5 -> new.b
4044 */
4057 ));
4059 #ifndef SQLITE_OMIT_FLOATING_POINT
4060 /* If the column has REAL affinity, it may currently be stored as an
4061 ** integer. Use OP_RealAffinity to make sure it is really real.
4062 **
4063 ** EVIDENCE-OF: R-60985-57662 SQLite will convert the value back to
4064 ** floating point when extracting it from the record. */
4067 ){
4069 }
4070 #endif
4072 }
4077 }
4088 }
4090 /*
4091 ** Form A:
4092 ** CASE x WHEN e1 THEN r1 WHEN e2 THEN r2 ... WHEN eN THEN rN ELSE y END
4093 **
4094 ** Form B:
4095 ** CASE WHEN e1 THEN r1 WHEN e2 THEN r2 ... WHEN eN THEN rN ELSE y END
4096 **
4097 ** Form A is can be transformed into the equivalent form B as follows:
4098 ** CASE WHEN x=e1 THEN r1 WHEN x=e2 THEN r2 ...
4099 ** WHEN x=eN THEN rN ELSE y END
4100 **
4101 ** X (if it exists) is in pExpr->pLeft.
4102 ** Y is in the last element of pExpr->x.pList if pExpr->x.pList->nExpr is
4103 ** odd. The Y is also optional. If the number of elements in x.pList
4104 ** is even, then Y is omitted and the "otherwise" result is NULL.
4105 ** Ei is in pExpr->pList->a[i*2] and Ri is pExpr->pList->a[i*2+1].
4106 **
4107 ** The result of the expression is the Ri for the first matching Ei,
4108 ** or if there is no matching Ei, the ELSE term Y, or if there is
4109 ** no ELSE term, NULL.
4110 */
4138 /* Ticket b351d95f9cd5ef17e9d9dbae18f5ca8611190001:
4139 ** The value in regFree1 might get SCopy-ed into the file result.
4140 ** So make sure that the regFree1 register is not reused for other
4141 ** purposes and possibly overwritten. */
4143 }
4151 }
4160 }
4167 }
4172 }
4173 #ifndef SQLITE_OMIT_TRIGGER
4179 );
4184 }
4187 }
4196 }
4199 }
4200 #endif
4201 }
4205 }
4207 /*
4208 ** Factor out the code of the given expression to initialization time.
4209 **
4210 ** If regDest>=0 then the result is always stored in that register and the
4211 ** result is not reusable. If regDest<0 then this routine is free to
4212 ** store the value whereever it wants. The register where the expression
4213 ** is stored is returned. When regDest<0, two identical expressions will
4214 ** code to the same register.
4215 */
4220 ){
4230 }
4231 }
4232 }
4240 }
4243 }
4245 /*
4246 ** Generate code to evaluate an expression and store the results
4247 ** into a register. Return the register number where the results
4248 ** are stored.
4249 **
4250 ** If the register is a temporary register that can be deallocated,
4251 ** then write its number into *pReg. If the result register is not
4252 ** a temporary, then set *pReg to zero.
4253 **
4254 ** If pExpr is a constant, then this routine might generate this
4255 ** code to fill the register in the initialization section of the
4256 ** VDBE program, in order to factor it out of the evaluation loop.
4257 */
4264 ){
4275 }
4276 }
4278 }
4280 /*
4281 ** Generate code that will evaluate expression pExpr and store the
4282 ** results in register target. The results are guaranteed to appear
4283 ** in register target.
4284 */
4296 }
4297 }
4298 }
4300 /*
4301 ** Make a transient copy of expression pExpr and then code it using
4302 ** sqlite3ExprCode(). This routine works just like sqlite3ExprCode()
4303 ** except that the input expression is guaranteed to be unchanged.
4304 */
4310 }
4312 /*
4313 ** Generate code that will evaluate expression pExpr and store the
4314 ** results in register target. The results are guaranteed to appear
4315 ** in register target. If the expression is constant, then this routine
4316 ** might choose to code the expression at initialization time.
4317 */
4323 }
4324 }
4326 /*
4327 ** Generate code that evaluates the given expression and puts the result
4328 ** in register target.
4329 **
4330 ** Also make a copy of the expression results into another "cache" register
4331 ** and modify the expression so that the next time it is evaluated,
4332 ** the result is a copy of the cache register.
4333 **
4334 ** This routine is used for expressions that are used multiple
4335 ** times. They are evaluated once and the results of the expression
4336 ** are reused.
4337 */
4348 }
4350 /*
4351 ** Generate code that pushes the value of every element of the given
4352 ** expression list into a sequence of registers beginning at target.
4353 **
4354 ** Return the number of elements evaluated. The number returned will
4355 ** usually be pList->nExpr but might be reduced if SQLITE_ECEL_OMITREF
4356 ** is defined.
4357 **
4358 ** The SQLITE_ECEL_DUP flag prevents the arguments from being
4359 ** filled using OP_SCopy. OP_Copy must be used instead.
4360 **
4361 ** The SQLITE_ECEL_FACTOR argument allows constant arguments to be
4362 ** factored out into initialization code.
4363 **
4364 ** The SQLITE_ECEL_REF flag means that expressions in the list with
4365 ** ExprList.a[].u.x.iOrderByCol>0 have already been evaluated and stored
4366 ** in registers at srcReg, and so the value can be copied from there.
4367 ** If SQLITE_ECEL_OMITREF is also set, then the values with u.x.iOrderByCol>0
4368 ** are simply omitted rather than being copied from srcReg.
4369 */
4375 u8 flags /* SQLITE_ECEL_* flags */
4376 ){
4388 #ifdef SQLITE_ENABLE_SORTER_REFERENCES
4390 i--;
4391 n--;
4393 #endif
4396 i--;
4397 n--;
4400 }
4411 ){
4415 }
4416 }
4417 }
4418 }
4420 }
4422 /*
4423 ** Generate code for a BETWEEN operator.
4424 **
4425 ** x BETWEEN y AND z
4426 **
4427 ** The above is equivalent to
4428 **
4429 ** x>=y AND x<=z
4430 **
4431 ** Code it as such, taking care to do the common subexpression
4432 ** elimination of x.
4433 **
4434 ** The xJumpIf parameter determines details:
4435 **
4436 ** NULL: Store the boolean result in reg[dest]
4437 ** sqlite3ExprIfTrue: Jump to dest if true
4438 ** sqlite3ExprIfFalse: Jump to dest if false
4439 **
4440 ** The jumpIfNull parameter is ignored if xJumpIf is NULL.
4441 */
4448 ){
4475 /* Mark the expression is being from the ON or USING clause of a join
4476 ** so that the sqlite3ExprCodeTarget() routine will not attempt to move
4477 ** it into the Parse.pConstExpr list. We should use a new bit for this,
4478 ** for clarity, but we are out of bits in the Expr.flags field so we
4479 ** have to reuse the EP_FromJoin bit. Bummer. */
4482 }
4485 /* Ensure adequate test coverage */
4495 }
4497 /*
4498 ** Generate code for a boolean expression such that a jump is made
4499 ** to the label "dest" if the expression is true but execution
4500 ** continues straight thru if the expression is false.
4501 **
4502 ** If the expression evaluates to NULL (neither true nor false), then
4503 ** take the jump if the jumpIfNull flag is SQLITE_JUMPIFNULL.
4504 **
4505 ** This code depends on the fact that certain token values (ex: TK_EQ)
4506 ** are the same as opcode values (ex: OP_Eq) that implement the corresponding
4507 ** operation. Special comments in vdbe.c and the mkopcodeh.awk script in
4508 ** the make process cause these values to align. Assert()s in the code
4509 ** below verify that the numbers are aligned correctly.
4510 */
4532 }
4540 }
4545 }
4560 }
4562 }
4569 /* Fall thru */
4595 }
4606 }
4611 }
4612 #ifndef SQLITE_OMIT_SUBQUERY
4620 }
4621 #endif
4623 default_expr:
4627 /* No-op */
4634 }
4636 }
4637 }
4640 }
4642 /*
4643 ** Generate code for a boolean expression such that a jump is made
4644 ** to the label "dest" if the expression is false but execution
4645 ** continues straight thru if the expression is true.
4646 **
4647 ** If the expression evaluates to NULL (neither true nor false) then
4648 ** jump if jumpIfNull is SQLITE_JUMPIFNULL or fall through if jumpIfNull
4649 ** is 0.
4650 */
4662 /* The value of pExpr->op and op are related as follows:
4663 **
4664 ** pExpr->op op
4665 ** --------- ----------
4666 ** TK_ISNULL OP_NotNull
4667 ** TK_NOTNULL OP_IsNull
4668 ** TK_NE OP_Eq
4669 ** TK_EQ OP_Ne
4670 ** TK_GT OP_Le
4671 ** TK_LE OP_Gt
4672 ** TK_GE OP_Lt
4673 ** TK_LT OP_Ge
4674 **
4675 ** For other values of pExpr->op, op is undefined and unused.
4676 ** The value of TK_ and OP_ constants are arranged such that we
4677 ** can compute the mapping above using the following expression.
4678 ** Assert()s verify that the computation is correct.
4679 */
4682 /* Verify correct alignment of TK_ and OP_ constants
4683 */
4701 }
4711 }
4716 }
4726 /* IS TRUE and IS NOT FALSE */
4731 /* IS FALSE and IS NOT TRUE */
4734 }
4736 }
4743 /* Fall thru */
4769 }
4778 }
4783 }
4784 #ifndef SQLITE_OMIT_SUBQUERY
4792 }
4794 }
4795 #endif
4797 default_expr:
4801 /* no-op */
4808 }
4810 }
4811 }
4814 }
4816 /*
4817 ** Like sqlite3ExprIfFalse() except that a copy is made of pExpr before
4818 ** code generation, and that copy is deleted after code generation. This
4819 ** ensures that the original pExpr is unchanged.
4820 */
4826 }
4828 }
4830 /*
4831 ** Expression pVar is guaranteed to be an SQL variable. pExpr may be any
4832 ** type of expression.
4833 **
4834 ** If pExpr is a simple SQL value - an integer, real, string, blob
4835 ** or NULL value - then the VDBE currently being prepared is configured
4836 ** to re-prepare each time a new value is bound to variable pVar.
4837 **
4838 ** Additionally, if pExpr is a simple SQL value and the value is the
4839 ** same as that currently bound to variable pVar, non-zero is returned.
4840 ** Otherwise, if the values are not the same or if pExpr is not a simple
4841 ** SQL value, zero is returned.
4842 */
4856 }
4858 }
4861 }
4864 }
4866 /*
4867 ** Do a deep comparison of two expression trees. Return 0 if the two
4868 ** expressions are completely identical. Return 1 if they differ only
4869 ** by a COLLATE operator at the top level. Return 2 if there are differences
4870 ** other than the top-level COLLATE operator.
4871 **
4872 ** If any subelement of pB has Expr.iTable==(-1) then it is allowed
4873 ** to compare equal to an equivalent element in pA with Expr.iTable==iTab.
4874 **
4875 ** The pA side might be using TK_REGISTER. If that is the case and pB is
4876 ** not using TK_REGISTER but is otherwise equivalent, then still return 0.
4877 **
4878 ** Sometimes this routine will return 2 even if the two expressions
4879 ** really are equivalent. If we cannot prove that the expressions are
4880 ** identical, we return 2 just to be safe. So if this routine
4881 ** returns 2, then you do not really know for certain if the two
4882 ** expressions are the same. But if you get a 0 or 1 return, then you
4883 ** can be sure the expressions are the same. In the places where
4884 ** this routine is used, it does not hurt to get an extra 2 - that
4885 ** just might result in some slightly slower code. But returning
4886 ** an incorrect 0 or 1 could lead to a malfunction.
4887 **
4888 ** If pParse is not NULL then TK_VARIABLE terms in pA with bindings in
4889 ** pParse->pReprepare can be matched against literals in pB. The
4890 ** pParse->pVdbe->expmask bitmask is updated for each variable referenced.
4891 ** If pParse is NULL (the normal case) then any TK_VARIABLE term in
4892 ** Argument pParse should normally be NULL. If it is not NULL and pA or
4893 ** pB causes a return value of 2.
4894 */
4896 u32 combinedFlags;
4899 }
4902 }
4907 }
4909 }
4913 }
4916 }
4918 }
4926 }
4927 }
4939 }
4940 }
4942 }
4944 /*
4945 ** Compare two ExprList objects. Return 0 if they are identical and
4946 ** non-zero if they differ in any way.
4947 **
4948 ** If any subelement of pB has Expr.iTable==(-1) then it is allowed
4949 ** to compare equal to an equivalent element in pA with Expr.iTable==iTab.
4950 **
4951 ** This routine might return non-zero for equivalent ExprLists. The
4952 ** only consequence will be disabled optimizations. But this routine
4953 ** must never return 0 if the two ExprList objects are different, or
4954 ** a malfunction will result.
4955 **
4956 ** Two NULL pointers are considered to be the same. But a NULL pointer
4957 ** always differs from a non-NULL pointer.
4958 */
4969 }
4971 }
4973 /*
4974 ** Like sqlite3ExprCompare() except COLLATE operators at the top-level
4975 ** are ignored.
4976 */
4981 iTab);
4982 }
4984 /*
4985 ** Return true if we can prove the pE2 will always be true if pE1 is
4986 ** true. Return false if we cannot complete the proof or if pE2 might
4987 ** be false. Examples:
4988 **
4989 ** pE1: x==5 pE2: x==5 Result: true
4990 ** pE1: x>0 pE2: x==5 Result: false
4991 ** pE1: x=21 pE2: x=21 OR y=43 Result: true
4992 ** pE1: x!=123 pE2: x IS NOT NULL Result: true
4993 ** pE1: x!=?1 pE2: x IS NOT NULL Result: true
4994 ** pE1: x IS NULL pE2: x IS NOT NULL Result: false
4995 ** pE1: x IS ?2 pE2: x IS NOT NULL Reuslt: false
4996 **
4997 ** When comparing TK_COLUMN nodes between pE1 and pE2, if pE2 has
4998 ** Expr.iTable<0 then assume a table number given by iTab.
4999 **
5000 ** If pParse is not NULL, then the values of bound variables in pE1 are
5001 ** compared against literal values in pE2 and pParse->pVdbe->expmask is
5002 ** modified to record which bound variables are referenced. If pParse
5003 ** is NULL, then false will be returned if pE1 contains any bound variables.
5004 **
5005 ** When in doubt, return false. Returning true might give a performance
5006 ** improvement. Returning false might cause a performance reduction, but
5007 ** it will always give the correct answer and is hence always safe.
5008 */
5012 }
5016 ){
5018 }
5023 }
5025 }
5027 /*
5028 ** This is the Expr node callback for sqlite3ExprImpliesNotNullRow().
5029 ** If the expression node requires that the table at pWalker->iCur
5030 ** have a non-NULL column, then set pWalker->eCode to 1 and abort.
5031 */
5033 /* This routine is only called for WHERE clause expressions and so it
5034 ** cannot have any TK_AGG_COLUMN entries because those are only found
5035 ** in HAVING clauses. We can get a TK_AGG_FUNCTION in a WHERE clause,
5036 ** but that is an illegal construct and the query will be rejected at
5037 ** a later stage of processing, so the TK_AGG_FUNCTION case does not
5038 ** need to be considered here. */
5065 }
5068 /* Virtual tables are allowed to use constraints like x=NULL. So
5069 ** a term of the form x=y does not prove that y is not null if x
5070 ** is the column of a virtual table */
5085 ){
5087 }
5090 }
5091 }
5093 /*
5094 ** Return true (non-zero) if expression p can only be true if at least
5095 ** one column of table iTab is non-null. In other words, return true
5096 ** if expression p will always be NULL or false if every column of iTab
5097 ** is NULL.
5098 **
5099 ** False negatives are acceptable. In other words, it is ok to return
5100 ** zero even if expression p will never be true of every column of iTab
5101 ** is NULL. A false negative is merely a missed optimization opportunity.
5102 **
5103 ** False positives are not allowed, however. A false positive may result
5104 ** in an incorrect answer.
5105 **
5106 ** Terms of p that are marked with EP_FromJoin (and hence that come from
5107 ** the ON or USING clauses of LEFT JOINS) are excluded from the analysis.
5108 **
5109 ** This routine is used to check if a LEFT JOIN can be converted into
5110 ** an ordinary JOIN. The p argument is the WHERE clause. If the WHERE
5111 ** clause requires that some column of the right table of the LEFT JOIN
5112 ** be non-NULL, then the LEFT JOIN can be safely converted into an
5113 ** ordinary join.
5114 */
5116 Walker w;
5124 }
5126 /*
5127 ** An instance of the following structure is used by the tree walker
5128 ** to determine if an expression can be evaluated by reference to the
5129 ** index only, without having to do a search for the corresponding
5130 ** table entry. The IdxCover.pIdx field is the index. IdxCover.iCur
5131 ** is the cursor for the table.
5132 */
5136 };
5138 /*
5139 ** Check to see if there are references to columns in table
5140 ** pWalker->u.pIdxCover->iCur can be satisfied using the index
5141 ** pWalker->u.pIdxCover->pIdx.
5142 */
5147 ){
5150 }
5152 }
5154 /*
5155 ** Determine if an index pIdx on table with cursor iCur contains will
5156 ** the expression pExpr. Return true if the index does cover the
5157 ** expression and false if the pExpr expression references table columns
5158 ** that are not found in the index pIdx.
5159 **
5160 ** An index covering an expression means that the expression can be
5161 ** evaluated using only the index and without having to lookup the
5162 ** corresponding table entry.
5163 */
5168 ){
5169 Walker w;
5178 }
5181 /*
5182 ** An instance of the following structure is used by the tree walker
5183 ** to count references to table columns in the arguments of an
5184 ** aggregate function, in order to implement the
5185 ** sqlite3FunctionThisSrc() routine.
5186 */
5191 };
5193 /*
5194 ** Count the number of references to columns.
5195 */
5197 /* The NEVER() on the second term is because sqlite3FunctionUsesThisSrc()
5198 ** is always called before sqlite3ExprAnalyzeAggregates() and so the
5199 ** TK_COLUMNs have not yet been converted into TK_AGG_COLUMN. If
5200 ** sqlite3FunctionUsesThisSrc() is used differently in the future, the
5201 ** NEVER() will need to be removed. */
5209 }
5214 }
5215 }
5217 }
5219 /*
5220 ** Determine if any of the arguments to the pExpr Function reference
5221 ** pSrcList. Return true if they do. Also return true if the function
5222 ** has no arguments or has only constant arguments. Return false if pExpr
5223 ** references columns but not columns of tables found in pSrcList.
5224 */
5226 Walker w;
5237 }
5239 /*
5240 ** Add a new element to the pAggInfo->aCol[] array. Return the index of
5241 ** the new element. Return a negative number if malloc fails.
5242 */
5246 db,
5250 &i
5251 );
5253 }
5255 /*
5256 ** Add a new element to the pAggInfo->aFunc[] array. Return the index of
5257 ** the new element. Return a negative number if malloc fails.
5258 */
5262 db,
5266 &i
5267 );
5269 }
5271 /*
5272 ** This is the xExprCallback for a tree walker. It is used to
5273 ** implement sqlite3ExprAnalyzeAggregates(). See sqlite3ExprAnalyzeAggregates
5274 ** for additional information.
5275 */
5289 /* Check to see if the column is in one of the tables in the FROM
5290 ** clause of the aggregate query */
5297 /* If we reach this point, it means that pExpr refers to a table
5298 ** that is in the FROM clause of the aggregate query.
5299 **
5300 ** Make an entry for the column in pAggInfo->aCol[] if there
5301 ** is not an entry there already.
5302 */
5309 }
5310 }
5313 ){
5332 }
5333 }
5334 }
5337 }
5338 }
5339 /* There is now an entry for pExpr in pAggInfo->aCol[] (either
5340 ** because it was there before or because we just created it).
5341 ** Convert the pExpr to be a TK_AGG_COLUMN referring to that
5342 ** pAggInfo->aCol[] entry.
5343 */
5351 }
5353 }
5357 ){
5358 /* Check to see if pExpr is a duplicate of another aggregate
5359 ** function that is already in the pAggInfo structure
5360 */
5365 }
5366 }
5368 /* pExpr is original. Make a new entry in pAggInfo->aFunc[]
5369 */
5385 }
5386 }
5387 }
5388 /* Make pExpr point to the appropriate pAggInfo->aFunc[] entry
5389 */
5397 }
5398 }
5399 }
5401 }
5406 }
5410 }
5412 /*
5413 ** Analyze the pExpr expression looking for aggregate functions and
5414 ** for variables that need to be added to AggInfo object that pNC->pAggInfo
5415 ** points to. Additional entries are made on the AggInfo object as
5416 ** necessary.
5417 **
5418 ** This routine should only be called after the expression has been
5419 ** analyzed by sqlite3ResolveExprNames().
5420 */
5422 Walker w;
5430 }
5432 /*
5433 ** Call sqlite3ExprAnalyzeAggregates() for every expression in an
5434 ** expression list. Return the number of errors.
5435 **
5436 ** If an error is found, the analysis is cut short.
5437 */
5444 }
5445 }
5446 }
5448 /*
5449 ** Allocate a single new register for use to hold some intermediate result.
5450 */
5454 }
5456 }
5458 /*
5459 ** Deallocate a register, making available for reuse for some other
5460 ** purpose.
5461 **
5462 ** If a register is currently being used by the column cache, then
5463 ** the deallocation is deferred until the column cache line that uses
5464 ** the register becomes stale.
5465 */
5474 }
5475 }
5477 }
5478 }
5480 /*
5481 ** Allocate or deallocate a block of nReg consecutive registers.
5482 */
5495 }
5497 }
5502 }
5507 }
5508 }
5510 /*
5511 ** Mark all temporary registers as being unavailable for reuse.
5512 */
5516 }
5518 /*
5519 ** Validate that no temporary register falls within the range of
5520 ** iFirst..iLast, inclusive. This routine is only call from within assert()
5521 ** statements.
5522 */
5523 #ifdef SQLITE_DEBUG
5529 ){
5531 }
5535 }
5536 }
5538 }