| blob | 91eb44b8eba9ae61ec0c9bc9f5fe9269d6eaed31 |
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 */
2422 #ifdef SQLITE_ENABLE_COLUMN_USED_MASK
2426 #endif
2430 }
2431 }
2433 }
2439 /* If no preexisting index is available for the IN clause
2440 ** and IN_INDEX_NOOP is an allowed reply
2441 ** and the RHS of the IN operator is a list, not a subquery
2442 ** and the RHS is not constant or has two or fewer terms,
2443 ** then it is not worth creating an ephemeral table to evaluate
2444 ** the IN operator so return IN_INDEX_NOOP.
2445 */
2450 ){
2452 }
2455 /* Could not find an existing table or index to use as the RHS b-tree.
2456 ** We will have to generate an ephemeral table to do the job.
2457 */
2465 }
2468 }
2473 }
2479 }
2481 }
2482 #endif
2484 #ifndef SQLITE_OMIT_SUBQUERY
2485 /*
2486 ** Argument pExpr is an (?, ?...) IN(...) expression. This
2487 ** function allocates and returns a nul-terminated string containing
2488 ** the affinities to be used for each column of the comparison.
2489 **
2490 ** It is the responsibility of the caller to ensure that the returned
2491 ** string is eventually freed using sqlite3DbFree().
2492 */
2510 }
2511 }
2513 }
2515 }
2516 #endif
2518 #ifndef SQLITE_OMIT_SUBQUERY
2519 /*
2520 ** Load the Parse object passed as the first argument with an error
2521 ** message of the form:
2522 **
2523 ** "sub-select returns N columns - expected M"
2524 */
2528 }
2529 #endif
2531 /*
2532 ** Expression pExpr is a vector that has been used in a context where
2533 ** it is not permitted. If pExpr is a sub-select vector, this routine
2534 ** loads the Parse object with a message of the form:
2535 **
2536 ** "sub-select returns N columns - expected 1"
2537 **
2538 ** Or, if it is a regular scalar vector:
2539 **
2540 ** "row value misused"
2541 */
2543 #ifndef SQLITE_OMIT_SUBQUERY
2547 #endif
2548 {
2550 }
2551 }
2553 /*
2554 ** Generate code for scalar subqueries used as a subquery expression, EXISTS,
2555 ** or IN operators. Examples:
2556 **
2557 ** (SELECT a FROM b) -- subquery
2558 ** EXISTS (SELECT a FROM b) -- EXISTS subquery
2559 ** x IN (4,5,11) -- IN operator with list on right-hand side
2560 ** x IN (SELECT a FROM b) -- IN operator with subquery on the right
2561 **
2562 ** The pExpr parameter describes the expression that contains the IN
2563 ** operator or subquery.
2564 **
2565 ** If parameter isRowid is non-zero, then expression pExpr is guaranteed
2566 ** to be of the form "<rowid> IN (?, ?, ?)", where <rowid> is a reference
2567 ** to some integer key column of a table B-Tree. In this case, use an
2568 ** intkey B-Tree to store the set of IN(...) values instead of the usual
2569 ** (slower) variable length keys B-Tree.
2570 **
2571 ** If rMayHaveNull is non-zero, that means that the operation is an IN
2572 ** (not a SELECT or EXISTS) and that the RHS might contains NULLs.
2573 ** All this routine does is initialize the register given by rMayHaveNull
2574 ** to NULL. Calling routines will take care of changing this register
2575 ** value to non-NULL if the RHS is NULL-free.
2576 **
2577 ** For a SELECT or EXISTS operator, return the register that holds the
2578 ** result. For a multi-column SELECT, the result is stored in a contiguous
2579 ** array of registers and the return value is the register of the left-most
2580 ** result column. Return 0 for IN operators or if an error occurs.
2581 */
2582 #ifndef SQLITE_OMIT_SUBQUERY
2588 ){
2595 /* The evaluation of the IN/EXISTS/SELECT must be repeated every time it
2596 ** is encountered if any of the following is true:
2597 **
2598 ** * The right-hand side is a correlated subquery
2599 ** * The right-hand side is an expression list containing variables
2600 ** * We are inside a trigger
2601 **
2602 ** If all of the above are false, then we can run this code just once
2603 ** save the results, and reuse the same result on subsequent invocations.
2604 */
2607 }
2619 /* Whether this is an 'x IN(SELECT...)' or an 'x IN(<exprlist>)'
2620 ** expression it is handled the same way. An ephemeral table is
2621 ** filled with index keys representing the results from the
2622 ** SELECT or the <exprlist>.
2623 **
2624 ** If the 'x' expression is a column value, or the SELECT...
2625 ** statement returns a column value, then the affinity of that
2626 ** column is used to build the index keys. If both 'x' and the
2627 ** SELECT... statement are columns, then numeric affinity is used
2628 ** if either column has NUMERIC or INTEGER affinity. If neither
2629 ** 'x' nor the SELECT... statement are columns, then numeric affinity
2630 ** is used.
2631 */
2638 /* Case 1: expr IN (SELECT ...)
2639 **
2640 ** Generate code to write the results of the select into the temporary
2641 ** table allocated and opened above.
2642 */
2648 ));
2650 /* If the LHS and RHS of the IN operator do not match, that
2651 ** error will have been caught long before we reach this point. */
2653 SelectDest dest;
2664 }
2674 );
2675 }
2676 }
2678 /* Case 2: expr IN (exprlist)
2679 **
2680 ** For each expression, build an index key from the evaluation and
2681 ** store it in the temporary table. If <expr> is a column, then use
2682 ** that columns affinity when building index keys. If <expr> is not
2683 ** a column, use numeric affinity.
2684 */
2693 }
2697 }
2699 /* Loop through each expression in <exprlist>. */
2707 /* If the expression is not constant then we will need to
2708 ** disable the test that was generated above that makes sure
2709 ** this code only executes once. Because for a non-constant
2710 ** expression we need to rerun this code each time.
2711 */
2715 }
2717 /* Evaluate the expression and insert it into the temp table */
2731 }
2732 }
2733 }
2736 }
2739 }
2741 }
2746 /* Case 3: (SELECT ... FROM ...)
2747 ** or: EXISTS(SELECT ... FROM ...)
2748 **
2749 ** For a SELECT, generate code to put the values for all columns of
2750 ** the first row into an array of registers and return the index of
2751 ** the first register.
2752 **
2753 ** If this is an EXISTS, write an integer 0 (not exists) or 1 (exists)
2754 ** into a register and return that register number.
2755 **
2756 ** In both cases, the query is augmented with "LIMIT 1". Any
2757 ** preexisting limit is discarded in place of the new LIMIT 1.
2758 */
2785 }
2792 }
2796 }
2800 }
2801 }
2805 }
2809 }
2813 }
2816 #ifndef SQLITE_OMIT_SUBQUERY
2817 /*
2818 ** Expr pIn is an IN(...) expression. This function checks that the
2819 ** sub-select on the RHS of the IN() operator has the same number of
2820 ** columns as the vector on the LHS. Or, if the RHS of the IN() is not
2821 ** a sub-query, that the LHS is a vector of size 1.
2822 */
2829 }
2833 }
2835 }
2836 #endif
2838 #ifndef SQLITE_OMIT_SUBQUERY
2839 /*
2840 ** Generate code for an IN expression.
2841 **
2842 ** x IN (SELECT ...)
2843 ** x IN (value, value, ...)
2844 **
2845 ** The left-hand side (LHS) is a scalar or vector expression. The
2846 ** right-hand side (RHS) is an array of zero or more scalar values, or a
2847 ** subquery. If the RHS is a subquery, the number of result columns must
2848 ** match the number of columns in the vector on the LHS. If the RHS is
2849 ** a list of values, the LHS must be a scalar.
2850 **
2851 ** The IN operator is true if the LHS value is contained within the RHS.
2852 ** The result is false if the LHS is definitely not in the RHS. The
2853 ** result is NULL if the presence of the LHS in the RHS cannot be
2854 ** determined due to NULLs.
2855 **
2856 ** This routine generates code that jumps to destIfFalse if the LHS is not
2857 ** contained within the RHS. If due to NULLs we cannot determine if the LHS
2858 ** is contained in the RHS then jump to destIfNull. If the LHS is contained
2859 ** within the RHS then fall through.
2860 **
2861 ** See the separate in-operator.md documentation file in the canonical
2862 ** SQLite source tree for additional information.
2863 */
2869 ){
2893 );
2896 /* Attempt to compute the RHS. After this step, if anything other than
2897 ** IN_INDEX_NOOP is returned, the table opened ith cursor pExpr->iTable
2898 ** contains the values that make up the RHS. If IN_INDEX_NOOP is returned,
2899 ** the RHS has not yet been coded. */
2909 );
2910 #ifdef SQLITE_DEBUG
2911 /* Confirm that aiMap[] contains nVector integer values between 0 and
2912 ** nVector-1. */
2917 }
2918 #endif
2920 /* Code the LHS, the <expr> from "<expr> IN (...)". If the LHS is a
2921 ** vector, then it is stored in an array of nVector registers starting
2922 ** at r1.
2923 **
2924 ** sqlite3FindInIndex() might have reordered the fields of the LHS vector
2925 ** so that the fields are in the same order as an existing index. The
2926 ** aiMap[] array contains a mapping from the original LHS field order to
2927 ** the field order that matches the RHS index.
2928 */
2933 /* LHS fields are not reordered */
2936 /* Need to reorder the LHS fields according to aiMap */
2940 }
2941 }
2943 /* If sqlite3FindInIndex() did not find or create an index that is
2944 ** suitable for evaluating the IN operator, then evaluate using a
2945 ** sequence of comparisons.
2946 **
2947 ** This is step (1) in the in-operator.md optimized algorithm.
2948 */
2960 }
2965 }
2977 }
2979 }
2983 }
2987 }
2989 /* Step 2: Check to see if the LHS contains any NULL columns. If the
2990 ** LHS does contain NULLs then the result must be either FALSE or NULL.
2991 ** We will then skip the binary search of the RHS.
2992 */
2997 }
3003 }
3004 }
3006 /* Step 3. The LHS is now known to be non-NULL. Do the binary search
3007 ** of the RHS using the LHS as a probe. If found, the result is
3008 ** true.
3009 */
3011 /* In this case, the RHS is the ROWID of table b-tree and so we also
3012 ** know that the RHS is non-NULL. Hence, we combine steps 3 and 4
3013 ** into a single opcode. */
3020 /* Combine Step 3 and Step 5 into a single opcode */
3024 }
3025 /* Ordinary Step 3, for the case where FALSE and NULL are distinct */
3028 }
3030 /* Step 4. If the RHS is known to be non-NULL and we did not find
3031 ** an match on the search above, then the result must be FALSE.
3032 */
3036 }
3038 /* Step 5. If we do not care about the difference between NULL and
3039 ** FALSE, then just return false.
3040 */
3043 /* Step 6: Loop through rows of the RHS. Compare each row to the LHS.
3044 ** If any comparison is NULL, then the result is NULL. If all
3045 ** comparisons are FALSE then the final result is FALSE.
3046 **
3047 ** For a scalar LHS, it is sufficient to check just the first row
3048 ** of the RHS.
3049 */
3056 /* For nVector==1, combine steps 6 and 7 by immediately returning
3057 ** FALSE if the first comparison is not NULL */
3059 }
3071 }
3078 /* Step 7: If we reach this point, we know that the result must
3079 ** be false. */
3081 }
3083 /* Jumps here in order to return true. */
3086 sqlite3ExprCodeIN_finished:
3090 sqlite3ExprCodeIN_oom_error:
3093 }
3096 #ifndef SQLITE_OMIT_FLOATING_POINT
3097 /*
3098 ** Generate an instruction that will put the floating point
3099 ** value described by z[0..n-1] into register iMem.
3100 **
3101 ** The z[] string will probably not be zero-terminated. But the
3102 ** z[n] character is guaranteed to be something that does not look
3103 ** like the continuation of the number.
3104 */
3112 }
3113 }
3114 #endif
3117 /*
3118 ** Generate an instruction that will put the integer describe by
3119 ** text z[0..n-1] into register iMem.
3120 **
3121 ** Expr.u.zToken is always UTF8 and zero-terminated.
3122 */
3132 i64 value;
3137 #ifdef SQLITE_OMIT_FLOATING_POINT
3139 #else
3140 #ifndef SQLITE_OMIT_HEX_INTEGER
3144 #endif
3145 {
3147 }
3148 #endif
3152 }
3153 }
3154 }
3156 /*
3157 ** Erase column-cache entry number i
3158 */
3163 }
3164 }
3168 }
3169 }
3172 /*
3173 ** Record in the column cache that a particular column from a
3174 ** particular table is stored in a particular register.
3175 */
3182 /* Unless an error has occurred, register numbers are always positive. */
3186 /* The SQLITE_ColumnCache flag disables the column cache. This is used
3187 ** for testing only - to verify that SQLite always gets the same answer
3188 ** with and without the column cache.
3189 */
3192 /* First replace any existing entry.
3193 **
3194 ** Actually, the way the column cache is currently used, we are guaranteed
3195 ** that the object will never already be in cache. Verify this guarantee.
3196 */
3197 #ifndef NDEBUG
3200 }
3201 #endif
3203 /* If the cache is already full, delete the least recently used entry */
3211 }
3212 }
3216 }
3218 /* Add the new entry to the end of the cache */
3225 }
3227 /*
3228 ** Indicate that registers between iReg..iReg+nReg-1 are being overwritten.
3229 ** Purge the range of registers from the column cache.
3230 */
3238 i++;
3239 }
3240 }
3241 }
3243 /*
3244 ** Remember the current column cache context. Any new entries added
3245 ** added to the column cache after this call are removed when the
3246 ** corresponding pop occurs.
3247 */
3250 #ifdef SQLITE_DEBUG
3253 }
3254 #endif
3255 }
3257 /*
3258 ** Remove from the column cache any entries that were added since the
3259 ** the previous sqlite3ExprCachePush operation. In other words, restore
3260 ** the cache to the state it was in prior the most recent Push.
3261 */
3266 #ifdef SQLITE_DEBUG
3269 }
3270 #endif
3275 i++;
3276 }
3277 }
3278 }
3280 /*
3281 ** When a cached column is reused, make sure that its register is
3282 ** no longer available as a temp register. ticket #3879: that same
3283 ** register might be in the cache in multiple places, so be sure to
3284 ** get them all.
3285 */
3292 }
3293 }
3294 }
3296 /* Generate code that will load into register regOut a value that is
3297 ** appropriate for the iIdxCol-th column of index pIdx.
3298 */
3305 ){
3316 }
3317 }
3319 /*
3320 ** Generate code to extract the value of the iCol-th column of a table.
3321 */
3328 ){
3332 }
3340 }
3342 }
3345 }
3346 }
3348 /*
3349 ** Generate code that will extract the iColumn-th column from
3350 ** table pTab and store the column value in a register.
3351 **
3352 ** An effort is made to store the column value in register iReg. This
3353 ** is not garanteeed for GetColumn() - the result can be stored in
3354 ** any register. But the result is guaranteed to land in register iReg
3355 ** for GetColumnToReg().
3356 **
3357 ** There must be an open cursor to pTab in iTable when this routine
3358 ** is called. If iColumn<0 then code is generated that extracts the rowid.
3359 */
3366 u8 p5 /* P5 value for OP_Column + FLAGS */
3367 ){
3377 }
3378 }
3385 }
3387 }
3394 ){
3397 }
3400 /*
3401 ** Clear all column cache entries.
3402 */
3406 #ifdef SQLITE_DEBUG
3409 }
3410 #endif
3414 ){
3416 }
3417 }
3419 }
3421 /*
3422 ** Record the fact that an affinity change has occurred on iCount
3423 ** registers starting with iStart.
3424 */
3427 }
3429 /*
3430 ** Generate code to move content from registers iFrom...iFrom+nReg-1
3431 ** over to iTo..iTo+nReg-1. Keep the column cache up-to-date.
3432 */
3437 }
3439 #if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
3440 /*
3441 ** Return true if any register in the range iFrom..iTo (inclusive)
3442 ** is used as part of the column cache.
3443 **
3444 ** This routine is used within assert() and testcase() macros only
3445 ** and does not appear in a normal build.
3446 */
3453 }
3455 }
3459 /*
3460 ** Convert a scalar expression node to a TK_REGISTER referencing
3461 ** register iReg. The caller must ensure that iReg already contains
3462 ** the correct value for the expression.
3463 */
3469 }
3471 /*
3472 ** Evaluate an expression (either a vector or a scalar expression) and store
3473 ** the result in continguous temporary registers. Return the index of
3474 ** the first register used to store the result.
3475 **
3476 ** If the returned result register is a temporary scalar, then also write
3477 ** that register number into *piFreeable. If the returned result register
3478 ** is not a temporary or if the expression is a vector set *piFreeable
3479 ** to 0.
3480 */
3489 #if SQLITE_OMIT_SUBQUERY
3491 #else
3493 #endif
3500 }
3501 }
3502 }
3504 }
3507 /*
3508 ** Generate code into the current Vdbe to evaluate the given
3509 ** expression. Attempt to store the results in register "target".
3510 ** Return the register where results are stored.
3511 **
3512 ** With this routine, there is no guarantee that results will
3513 ** be stored in target. The result might be stored in some other
3514 ** register if it is convenient to do so. The calling function
3515 ** must check the return code and move the results to the desired
3516 ** register.
3517 */
3532 }
3534 expr_code_doover:
3539 }
3551 }
3552 /* Otherwise, fall thru into the TK_COLUMN case */
3553 }
3558 /* Generating CHECK constraints or inserting into partial index */
3561 /* Coding an expression that is part of an index where column names
3562 ** in the index refer to the table to which the index belongs */
3564 }
3565 }
3569 }
3573 }
3577 }
3578 #ifndef SQLITE_OMIT_FLOATING_POINT
3583 }
3584 #endif
3589 }
3593 }
3594 #ifndef SQLITE_OMIT_BLOB_LITERAL
3608 }
3609 #endif
3620 }
3622 }
3625 }
3626 #ifndef SQLITE_OMIT_CAST
3628 /* Expressions of the form: CAST(pLeft AS token) */
3633 }
3639 }
3645 /* fall-through */
3668 }
3670 }
3700 }
3707 #ifndef SQLITE_OMIT_FLOATING_POINT
3712 #endif
3721 }
3723 }
3732 }
3744 }
3759 }
3767 }
3769 }
3782 /* SQL functions can be expensive. So try to move constant functions
3783 ** out of the inner loop, even if that means an extra OP_Copy. */
3785 }
3791 }
3796 #ifdef SQLITE_ENABLE_UNKNOWN_SQL_FUNCTION
3799 }
3800 #endif
3804 }
3806 /* Attempt a direct implementation of the built-in COALESCE() and
3807 ** IFNULL() functions. This avoids unnecessary evaluation of
3808 ** arguments past the first non-NULL argument.
3809 */
3821 }
3824 }
3826 /* The UNLIKELY() function is a no-op. The result is the value
3827 ** of the first argument.
3828 */
3832 }
3834 #ifdef SQLITE_DEBUG
3835 /* The AFFINITY() function evaluates to a string that describes
3836 ** the type affinity of the argument. This is used for testing of
3837 ** the SQLite type logic.
3838 */
3847 }
3848 #endif
3854 }
3857 }
3858 }
3865 }
3867 /* For length() and typeof() functions with a column argument,
3868 ** set the P5 parameter to the OP_Column opcode to OPFLAG_LENGTHARG
3869 ** or OPFLAG_TYPEOFARG respectively, to avoid unnecessary data
3870 ** loading.
3871 */
3873 u8 exprOp;
3883 }
3884 }
3892 }
3893 #ifndef SQLITE_OMIT_VIRTUALTABLE
3894 /* Possibly overload the function if the first argument is
3895 ** a virtual table column.
3896 **
3897 ** For infix functions (LIKE, GLOB, REGEXP, and MATCH) use the
3898 ** second argument, not the first, as the argument to test to
3899 ** see if it is a column in a virtual table. This is done because
3900 ** the left operand of infix functions (the operand we want to
3901 ** control overloading) ends up as the second argument to the
3902 ** function. The expression "A glob B" is equivalent to
3903 ** "glob(B,A). We want to use the A in "A glob B" to test
3904 ** for function overloading. But we use the B term in "glob(B,A)".
3905 */
3910 }
3911 #endif
3915 }
3916 #ifdef SQLITE_ENABLE_OFFSET_SQL_FUNC
3923 }
3925 #endif
3926 {
3930 }
3933 }
3935 }
3936 #ifndef SQLITE_OMIT_SUBQUERY
3946 }
3948 }
3953 }
3957 ){
3960 }
3962 }
3973 }
3977 /*
3978 ** x BETWEEN y AND z
3979 **
3980 ** This is equivalent to
3981 **
3982 ** x>=y AND x<=z
3983 **
3984 ** X is stored in pExpr->pLeft.
3985 ** Y is stored in pExpr->pList->a[0].pExpr.
3986 ** Z is stored in pExpr->pList->a[1].pExpr.
3987 */
3991 }
3997 }
4000 /* If the opcode is TK_TRIGGER, then the expression is a reference
4001 ** to a column in the new.* or old.* pseudo-tables available to
4002 ** trigger programs. In this case Expr.iTable is set to 1 for the
4003 ** new.* pseudo-table, or 0 for the old.* pseudo-table. Expr.iColumn
4004 ** is set to the column of the pseudo-table to read, or to -1 to
4005 ** read the rowid field.
4006 **
4007 ** The expression is implemented using an OP_Param opcode. The p1
4008 ** parameter is set to 0 for an old.rowid reference, or to (i+1)
4009 ** to reference another column of the old.* pseudo-table, where
4010 ** i is the index of the column. For a new.rowid reference, p1 is
4011 ** set to (n+1), where n is the number of columns in each pseudo-table.
4012 ** For a reference to any other column in the new.* pseudo-table, p1
4013 ** is set to (n+2+i), where n and i are as defined previously. For
4014 ** example, if the table on which triggers are being fired is
4015 ** declared as:
4016 **
4017 ** CREATE TABLE t1(a, b);
4018 **
4019 ** Then p1 is interpreted as follows:
4020 **
4021 ** p1==0 -> old.rowid p1==3 -> new.rowid
4022 ** p1==1 -> old.a p1==4 -> new.a
4023 ** p1==2 -> old.b p1==5 -> new.b
4024 */
4037 ));
4039 #ifndef SQLITE_OMIT_FLOATING_POINT
4040 /* If the column has REAL affinity, it may currently be stored as an
4041 ** integer. Use OP_RealAffinity to make sure it is really real.
4042 **
4043 ** EVIDENCE-OF: R-60985-57662 SQLite will convert the value back to
4044 ** floating point when extracting it from the record. */
4047 ){
4049 }
4050 #endif
4052 }
4057 }
4068 }
4070 /*
4071 ** Form A:
4072 ** CASE x WHEN e1 THEN r1 WHEN e2 THEN r2 ... WHEN eN THEN rN ELSE y END
4073 **
4074 ** Form B:
4075 ** CASE WHEN e1 THEN r1 WHEN e2 THEN r2 ... WHEN eN THEN rN ELSE y END
4076 **
4077 ** Form A is can be transformed into the equivalent form B as follows:
4078 ** CASE WHEN x=e1 THEN r1 WHEN x=e2 THEN r2 ...
4079 ** WHEN x=eN THEN rN ELSE y END
4080 **
4081 ** X (if it exists) is in pExpr->pLeft.
4082 ** Y is in the last element of pExpr->x.pList if pExpr->x.pList->nExpr is
4083 ** odd. The Y is also optional. If the number of elements in x.pList
4084 ** is even, then Y is omitted and the "otherwise" result is NULL.
4085 ** Ei is in pExpr->pList->a[i*2] and Ri is pExpr->pList->a[i*2+1].
4086 **
4087 ** The result of the expression is the Ri for the first matching Ei,
4088 ** or if there is no matching Ei, the ELSE term Y, or if there is
4089 ** no ELSE term, NULL.
4090 */
4118 /* Ticket b351d95f9cd5ef17e9d9dbae18f5ca8611190001:
4119 ** The value in regFree1 might get SCopy-ed into the file result.
4120 ** So make sure that the regFree1 register is not reused for other
4121 ** purposes and possibly overwritten. */
4123 }
4131 }
4140 }
4147 }
4152 }
4153 #ifndef SQLITE_OMIT_TRIGGER
4159 );
4164 }
4167 }
4176 }
4179 }
4180 #endif
4181 }
4185 }
4187 /*
4188 ** Factor out the code of the given expression to initialization time.
4189 **
4190 ** If regDest>=0 then the result is always stored in that register and the
4191 ** result is not reusable. If regDest<0 then this routine is free to
4192 ** store the value whereever it wants. The register where the expression
4193 ** is stored is returned. When regDest<0, two identical expressions will
4194 ** code to the same register.
4195 */
4200 ){
4210 }
4211 }
4212 }
4220 }
4223 }
4225 /*
4226 ** Generate code to evaluate an expression and store the results
4227 ** into a register. Return the register number where the results
4228 ** are stored.
4229 **
4230 ** If the register is a temporary register that can be deallocated,
4231 ** then write its number into *pReg. If the result register is not
4232 ** a temporary, then set *pReg to zero.
4233 **
4234 ** If pExpr is a constant, then this routine might generate this
4235 ** code to fill the register in the initialization section of the
4236 ** VDBE program, in order to factor it out of the evaluation loop.
4237 */
4244 ){
4255 }
4256 }
4258 }
4260 /*
4261 ** Generate code that will evaluate expression pExpr and store the
4262 ** results in register target. The results are guaranteed to appear
4263 ** in register target.
4264 */
4276 }
4277 }
4278 }
4280 /*
4281 ** Make a transient copy of expression pExpr and then code it using
4282 ** sqlite3ExprCode(). This routine works just like sqlite3ExprCode()
4283 ** except that the input expression is guaranteed to be unchanged.
4284 */
4290 }
4292 /*
4293 ** Generate code that will evaluate expression pExpr and store the
4294 ** results in register target. The results are guaranteed to appear
4295 ** in register target. If the expression is constant, then this routine
4296 ** might choose to code the expression at initialization time.
4297 */
4303 }
4304 }
4306 /*
4307 ** Generate code that evaluates the given expression and puts the result
4308 ** in register target.
4309 **
4310 ** Also make a copy of the expression results into another "cache" register
4311 ** and modify the expression so that the next time it is evaluated,
4312 ** the result is a copy of the cache register.
4313 **
4314 ** This routine is used for expressions that are used multiple
4315 ** times. They are evaluated once and the results of the expression
4316 ** are reused.
4317 */
4328 }
4330 /*
4331 ** Generate code that pushes the value of every element of the given
4332 ** expression list into a sequence of registers beginning at target.
4333 **
4334 ** Return the number of elements evaluated. The number returned will
4335 ** usually be pList->nExpr but might be reduced if SQLITE_ECEL_OMITREF
4336 ** is defined.
4337 **
4338 ** The SQLITE_ECEL_DUP flag prevents the arguments from being
4339 ** filled using OP_SCopy. OP_Copy must be used instead.
4340 **
4341 ** The SQLITE_ECEL_FACTOR argument allows constant arguments to be
4342 ** factored out into initialization code.
4343 **
4344 ** The SQLITE_ECEL_REF flag means that expressions in the list with
4345 ** ExprList.a[].u.x.iOrderByCol>0 have already been evaluated and stored
4346 ** in registers at srcReg, and so the value can be copied from there.
4347 ** If SQLITE_ECEL_OMITREF is also set, then the values with u.x.iOrderByCol>0
4348 ** are simply omitted rather than being copied from srcReg.
4349 */
4355 u8 flags /* SQLITE_ECEL_* flags */
4356 ){
4368 #ifdef SQLITE_ENABLE_SORTER_REFERENCES
4370 i--;
4371 n--;
4373 #endif
4376 i--;
4377 n--;
4380 }
4391 ){
4395 }
4396 }
4397 }
4398 }
4400 }
4402 /*
4403 ** Generate code for a BETWEEN operator.
4404 **
4405 ** x BETWEEN y AND z
4406 **
4407 ** The above is equivalent to
4408 **
4409 ** x>=y AND x<=z
4410 **
4411 ** Code it as such, taking care to do the common subexpression
4412 ** elimination of x.
4413 **
4414 ** The xJumpIf parameter determines details:
4415 **
4416 ** NULL: Store the boolean result in reg[dest]
4417 ** sqlite3ExprIfTrue: Jump to dest if true
4418 ** sqlite3ExprIfFalse: Jump to dest if false
4419 **
4420 ** The jumpIfNull parameter is ignored if xJumpIf is NULL.
4421 */
4428 ){
4455 /* Mark the expression is being from the ON or USING clause of a join
4456 ** so that the sqlite3ExprCodeTarget() routine will not attempt to move
4457 ** it into the Parse.pConstExpr list. We should use a new bit for this,
4458 ** for clarity, but we are out of bits in the Expr.flags field so we
4459 ** have to reuse the EP_FromJoin bit. Bummer. */
4462 }
4465 /* Ensure adequate test coverage */
4475 }
4477 /*
4478 ** Generate code for a boolean expression such that a jump is made
4479 ** to the label "dest" if the expression is true but execution
4480 ** continues straight thru if the expression is false.
4481 **
4482 ** If the expression evaluates to NULL (neither true nor false), then
4483 ** take the jump if the jumpIfNull flag is SQLITE_JUMPIFNULL.
4484 **
4485 ** This code depends on the fact that certain token values (ex: TK_EQ)
4486 ** are the same as opcode values (ex: OP_Eq) that implement the corresponding
4487 ** operation. Special comments in vdbe.c and the mkopcodeh.awk script in
4488 ** the make process cause these values to align. Assert()s in the code
4489 ** below verify that the numbers are aligned correctly.
4490 */
4512 }
4520 }
4525 }
4540 }
4542 }
4549 /* Fall thru */
4575 }
4586 }
4591 }
4592 #ifndef SQLITE_OMIT_SUBQUERY
4600 }
4601 #endif
4603 default_expr:
4607 /* No-op */
4614 }
4616 }
4617 }
4620 }
4622 /*
4623 ** Generate code for a boolean expression such that a jump is made
4624 ** to the label "dest" if the expression is false but execution
4625 ** continues straight thru if the expression is true.
4626 **
4627 ** If the expression evaluates to NULL (neither true nor false) then
4628 ** jump if jumpIfNull is SQLITE_JUMPIFNULL or fall through if jumpIfNull
4629 ** is 0.
4630 */
4642 /* The value of pExpr->op and op are related as follows:
4643 **
4644 ** pExpr->op op
4645 ** --------- ----------
4646 ** TK_ISNULL OP_NotNull
4647 ** TK_NOTNULL OP_IsNull
4648 ** TK_NE OP_Eq
4649 ** TK_EQ OP_Ne
4650 ** TK_GT OP_Le
4651 ** TK_LE OP_Gt
4652 ** TK_GE OP_Lt
4653 ** TK_LT OP_Ge
4654 **
4655 ** For other values of pExpr->op, op is undefined and unused.
4656 ** The value of TK_ and OP_ constants are arranged such that we
4657 ** can compute the mapping above using the following expression.
4658 ** Assert()s verify that the computation is correct.
4659 */
4662 /* Verify correct alignment of TK_ and OP_ constants
4663 */
4681 }
4691 }
4696 }
4706 /* IS TRUE and IS NOT FALSE */
4711 /* IS FALSE and IS NOT TRUE */
4714 }
4716 }
4723 /* Fall thru */
4749 }
4758 }
4763 }
4764 #ifndef SQLITE_OMIT_SUBQUERY
4772 }
4774 }
4775 #endif
4777 default_expr:
4781 /* no-op */
4788 }
4790 }
4791 }
4794 }
4796 /*
4797 ** Like sqlite3ExprIfFalse() except that a copy is made of pExpr before
4798 ** code generation, and that copy is deleted after code generation. This
4799 ** ensures that the original pExpr is unchanged.
4800 */
4806 }
4808 }
4810 /*
4811 ** Expression pVar is guaranteed to be an SQL variable. pExpr may be any
4812 ** type of expression.
4813 **
4814 ** If pExpr is a simple SQL value - an integer, real, string, blob
4815 ** or NULL value - then the VDBE currently being prepared is configured
4816 ** to re-prepare each time a new value is bound to variable pVar.
4817 **
4818 ** Additionally, if pExpr is a simple SQL value and the value is the
4819 ** same as that currently bound to variable pVar, non-zero is returned.
4820 ** Otherwise, if the values are not the same or if pExpr is not a simple
4821 ** SQL value, zero is returned.
4822 */
4836 }
4838 }
4841 }
4844 }
4846 /*
4847 ** Do a deep comparison of two expression trees. Return 0 if the two
4848 ** expressions are completely identical. Return 1 if they differ only
4849 ** by a COLLATE operator at the top level. Return 2 if there are differences
4850 ** other than the top-level COLLATE operator.
4851 **
4852 ** If any subelement of pB has Expr.iTable==(-1) then it is allowed
4853 ** to compare equal to an equivalent element in pA with Expr.iTable==iTab.
4854 **
4855 ** The pA side might be using TK_REGISTER. If that is the case and pB is
4856 ** not using TK_REGISTER but is otherwise equivalent, then still return 0.
4857 **
4858 ** Sometimes this routine will return 2 even if the two expressions
4859 ** really are equivalent. If we cannot prove that the expressions are
4860 ** identical, we return 2 just to be safe. So if this routine
4861 ** returns 2, then you do not really know for certain if the two
4862 ** expressions are the same. But if you get a 0 or 1 return, then you
4863 ** can be sure the expressions are the same. In the places where
4864 ** this routine is used, it does not hurt to get an extra 2 - that
4865 ** just might result in some slightly slower code. But returning
4866 ** an incorrect 0 or 1 could lead to a malfunction.
4867 **
4868 ** If pParse is not NULL then TK_VARIABLE terms in pA with bindings in
4869 ** pParse->pReprepare can be matched against literals in pB. The
4870 ** pParse->pVdbe->expmask bitmask is updated for each variable referenced.
4871 ** If pParse is NULL (the normal case) then any TK_VARIABLE term in
4872 ** Argument pParse should normally be NULL. If it is not NULL and pA or
4873 ** pB causes a return value of 2.
4874 */
4876 u32 combinedFlags;
4879 }
4882 }
4887 }
4889 }
4893 }
4896 }
4898 }
4906 }
4907 }
4919 }
4920 }
4922 }
4924 /*
4925 ** Compare two ExprList objects. Return 0 if they are identical and
4926 ** non-zero if they differ in any way.
4927 **
4928 ** If any subelement of pB has Expr.iTable==(-1) then it is allowed
4929 ** to compare equal to an equivalent element in pA with Expr.iTable==iTab.
4930 **
4931 ** This routine might return non-zero for equivalent ExprLists. The
4932 ** only consequence will be disabled optimizations. But this routine
4933 ** must never return 0 if the two ExprList objects are different, or
4934 ** a malfunction will result.
4935 **
4936 ** Two NULL pointers are considered to be the same. But a NULL pointer
4937 ** always differs from a non-NULL pointer.
4938 */
4949 }
4951 }
4953 /*
4954 ** Like sqlite3ExprCompare() except COLLATE operators at the top-level
4955 ** are ignored.
4956 */
4961 iTab);
4962 }
4964 /*
4965 ** Return true if we can prove the pE2 will always be true if pE1 is
4966 ** true. Return false if we cannot complete the proof or if pE2 might
4967 ** be false. Examples:
4968 **
4969 ** pE1: x==5 pE2: x==5 Result: true
4970 ** pE1: x>0 pE2: x==5 Result: false
4971 ** pE1: x=21 pE2: x=21 OR y=43 Result: true
4972 ** pE1: x!=123 pE2: x IS NOT NULL Result: true
4973 ** pE1: x!=?1 pE2: x IS NOT NULL Result: true
4974 ** pE1: x IS NULL pE2: x IS NOT NULL Result: false
4975 ** pE1: x IS ?2 pE2: x IS NOT NULL Reuslt: false
4976 **
4977 ** When comparing TK_COLUMN nodes between pE1 and pE2, if pE2 has
4978 ** Expr.iTable<0 then assume a table number given by iTab.
4979 **
4980 ** If pParse is not NULL, then the values of bound variables in pE1 are
4981 ** compared against literal values in pE2 and pParse->pVdbe->expmask is
4982 ** modified to record which bound variables are referenced. If pParse
4983 ** is NULL, then false will be returned if pE1 contains any bound variables.
4984 **
4985 ** When in doubt, return false. Returning true might give a performance
4986 ** improvement. Returning false might cause a performance reduction, but
4987 ** it will always give the correct answer and is hence always safe.
4988 */
4992 }
4996 ){
4998 }
5003 }
5005 }
5007 /*
5008 ** This is the Expr node callback for sqlite3ExprImpliesNotNullRow().
5009 ** If the expression node requires that the table at pWalker->iCur
5010 ** have a non-NULL column, then set pWalker->eCode to 1 and abort.
5011 */
5013 /* This routine is only called for WHERE clause expressions and so it
5014 ** cannot have any TK_AGG_COLUMN entries because those are only found
5015 ** in HAVING clauses. We can get a TK_AGG_FUNCTION in a WHERE clause,
5016 ** but that is an illegal construct and the query will be rejected at
5017 ** a later stage of processing, so the TK_AGG_FUNCTION case does not
5018 ** need to be considered here. */
5045 }
5048 /* Virtual tables are allowed to use constraints like x=NULL. So
5049 ** a term of the form x=y does not prove that y is not null if x
5050 ** is the column of a virtual table */
5065 ){
5067 }
5070 }
5071 }
5073 /*
5074 ** Return true (non-zero) if expression p can only be true if at least
5075 ** one column of table iTab is non-null. In other words, return true
5076 ** if expression p will always be NULL or false if every column of iTab
5077 ** is NULL.
5078 **
5079 ** False negatives are acceptable. In other words, it is ok to return
5080 ** zero even if expression p will never be true of every column of iTab
5081 ** is NULL. A false negative is merely a missed optimization opportunity.
5082 **
5083 ** False positives are not allowed, however. A false positive may result
5084 ** in an incorrect answer.
5085 **
5086 ** Terms of p that are marked with EP_FromJoin (and hence that come from
5087 ** the ON or USING clauses of LEFT JOINS) are excluded from the analysis.
5088 **
5089 ** This routine is used to check if a LEFT JOIN can be converted into
5090 ** an ordinary JOIN. The p argument is the WHERE clause. If the WHERE
5091 ** clause requires that some column of the right table of the LEFT JOIN
5092 ** be non-NULL, then the LEFT JOIN can be safely converted into an
5093 ** ordinary join.
5094 */
5096 Walker w;
5104 }
5106 /*
5107 ** An instance of the following structure is used by the tree walker
5108 ** to determine if an expression can be evaluated by reference to the
5109 ** index only, without having to do a search for the corresponding
5110 ** table entry. The IdxCover.pIdx field is the index. IdxCover.iCur
5111 ** is the cursor for the table.
5112 */
5116 };
5118 /*
5119 ** Check to see if there are references to columns in table
5120 ** pWalker->u.pIdxCover->iCur can be satisfied using the index
5121 ** pWalker->u.pIdxCover->pIdx.
5122 */
5127 ){
5130 }
5132 }
5134 /*
5135 ** Determine if an index pIdx on table with cursor iCur contains will
5136 ** the expression pExpr. Return true if the index does cover the
5137 ** expression and false if the pExpr expression references table columns
5138 ** that are not found in the index pIdx.
5139 **
5140 ** An index covering an expression means that the expression can be
5141 ** evaluated using only the index and without having to lookup the
5142 ** corresponding table entry.
5143 */
5148 ){
5149 Walker w;
5158 }
5161 /*
5162 ** An instance of the following structure is used by the tree walker
5163 ** to count references to table columns in the arguments of an
5164 ** aggregate function, in order to implement the
5165 ** sqlite3FunctionThisSrc() routine.
5166 */
5171 };
5173 /*
5174 ** Count the number of references to columns.
5175 */
5177 /* The NEVER() on the second term is because sqlite3FunctionUsesThisSrc()
5178 ** is always called before sqlite3ExprAnalyzeAggregates() and so the
5179 ** TK_COLUMNs have not yet been converted into TK_AGG_COLUMN. If
5180 ** sqlite3FunctionUsesThisSrc() is used differently in the future, the
5181 ** NEVER() will need to be removed. */
5189 }
5194 }
5195 }
5197 }
5199 /*
5200 ** Determine if any of the arguments to the pExpr Function reference
5201 ** pSrcList. Return true if they do. Also return true if the function
5202 ** has no arguments or has only constant arguments. Return false if pExpr
5203 ** references columns but not columns of tables found in pSrcList.
5204 */
5206 Walker w;
5217 }
5219 /*
5220 ** Add a new element to the pAggInfo->aCol[] array. Return the index of
5221 ** the new element. Return a negative number if malloc fails.
5222 */
5226 db,
5230 &i
5231 );
5233 }
5235 /*
5236 ** Add a new element to the pAggInfo->aFunc[] array. Return the index of
5237 ** the new element. Return a negative number if malloc fails.
5238 */
5242 db,
5246 &i
5247 );
5249 }
5251 /*
5252 ** This is the xExprCallback for a tree walker. It is used to
5253 ** implement sqlite3ExprAnalyzeAggregates(). See sqlite3ExprAnalyzeAggregates
5254 ** for additional information.
5255 */
5269 /* Check to see if the column is in one of the tables in the FROM
5270 ** clause of the aggregate query */
5277 /* If we reach this point, it means that pExpr refers to a table
5278 ** that is in the FROM clause of the aggregate query.
5279 **
5280 ** Make an entry for the column in pAggInfo->aCol[] if there
5281 ** is not an entry there already.
5282 */
5289 }
5290 }
5293 ){
5312 }
5313 }
5314 }
5317 }
5318 }
5319 /* There is now an entry for pExpr in pAggInfo->aCol[] (either
5320 ** because it was there before or because we just created it).
5321 ** Convert the pExpr to be a TK_AGG_COLUMN referring to that
5322 ** pAggInfo->aCol[] entry.
5323 */
5331 }
5333 }
5337 ){
5338 /* Check to see if pExpr is a duplicate of another aggregate
5339 ** function that is already in the pAggInfo structure
5340 */
5345 }
5346 }
5348 /* pExpr is original. Make a new entry in pAggInfo->aFunc[]
5349 */
5365 }
5366 }
5367 }
5368 /* Make pExpr point to the appropriate pAggInfo->aFunc[] entry
5369 */
5377 }
5378 }
5379 }
5381 }
5386 }
5390 }
5392 /*
5393 ** Analyze the pExpr expression looking for aggregate functions and
5394 ** for variables that need to be added to AggInfo object that pNC->pAggInfo
5395 ** points to. Additional entries are made on the AggInfo object as
5396 ** necessary.
5397 **
5398 ** This routine should only be called after the expression has been
5399 ** analyzed by sqlite3ResolveExprNames().
5400 */
5402 Walker w;
5410 }
5412 /*
5413 ** Call sqlite3ExprAnalyzeAggregates() for every expression in an
5414 ** expression list. Return the number of errors.
5415 **
5416 ** If an error is found, the analysis is cut short.
5417 */
5424 }
5425 }
5426 }
5428 /*
5429 ** Allocate a single new register for use to hold some intermediate result.
5430 */
5434 }
5436 }
5438 /*
5439 ** Deallocate a register, making available for reuse for some other
5440 ** purpose.
5441 **
5442 ** If a register is currently being used by the column cache, then
5443 ** the deallocation is deferred until the column cache line that uses
5444 ** the register becomes stale.
5445 */
5454 }
5455 }
5457 }
5458 }
5460 /*
5461 ** Allocate or deallocate a block of nReg consecutive registers.
5462 */
5475 }
5477 }
5482 }
5487 }
5488 }
5490 /*
5491 ** Mark all temporary registers as being unavailable for reuse.
5492 */
5496 }
5498 /*
5499 ** Validate that no temporary register falls within the range of
5500 ** iFirst..iLast, inclusive. This routine is only call from within assert()
5501 ** statements.
5502 */
5503 #ifdef SQLITE_DEBUG
5509 ){
5511 }
5515 }
5516 }
5518 }