lib/ddl/mysql_sql_generator.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * Mysql specific SQL code generator.
  19  *
  20  * @package    core_ddl
  21  * @copyright  1999 onwards Martin Dougiamas     http://dougiamas.com
  22  *             2001-3001 Eloy Lafuente (stronk7) http://contiento.com
  23  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  24  */
  25
  26 defined('MOODLE_INTERNAL') || die();
  27
  28 require_once($CFG->libdir.'/ddl/sql_generator.php');
  29
  30 /**
  31  * This class generate SQL code to be used against MySQL
  32  * It extends XMLDBgenerator so everything can be
  33  * overridden as needed to generate correct SQL.
  34  *
  35  * @package    core_ddl
  36  * @copyright  1999 onwards Martin Dougiamas     http://dougiamas.com
  37  *             2001-3001 Eloy Lafuente (stronk7) http://contiento.com
  38  * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  39  */
  40 class mysql_sql_generator extends sql_generator {
  41
  42     // Only set values that are different from the defaults present in XMLDBgenerator
  43
  44     /** @var string Used to quote names. */
  45     public $quote_string = '`';
  46
  47     /** @var string To define the default to set for NOT NULLs CHARs without default (null=do nothing).*/
  48     public $default_for_char = '';
  49
  50     /** @var bool To specify if the generator must use some DEFAULT clause to drop defaults.*/
  51     public $drop_default_value_required = true;
  52
  53     /** @var string The DEFAULT clause required to drop defaults.*/
  54     public $drop_default_value = null;
  55
  56     /** @var string To force primary key names to one string (null=no force).*/
  57     public $primary_key_name = '';
  58
  59     /** @var string Template to drop PKs. 'TABLENAME' and 'KEYNAME' will be replaced from this template.*/
  60     public $drop_primary_key = 'ALTER TABLE TABLENAME DROP PRIMARY KEY';
  61
  62     /** @var string Template to drop UKs. 'TABLENAME' and 'KEYNAME' will be replaced from this template.*/
  63     public $drop_unique_key = 'ALTER TABLE TABLENAME DROP KEY KEYNAME';
  64
  65     /** @var string Template to drop FKs. 'TABLENAME' and 'KEYNAME' will be replaced from this template.*/
  66     public $drop_foreign_key = 'ALTER TABLE TABLENAME DROP FOREIGN KEY KEYNAME';
  67
  68     /** @var bool True if the generator needs to add extra code to generate the sequence fields.*/
  69     public $sequence_extra_code = false;
  70
  71     /** @var string The particular name for inline sequences in this generator.*/
  72     public $sequence_name = 'auto_increment';
  73
  74     public $add_after_clause = true; // Does the generator need to add the after clause for fields
  75
  76     /** @var string Characters to be used as concatenation operator.*/
  77     public $concat_character = null;
  78
  79     /** @var string The SQL template to alter columns where the 'TABLENAME' and 'COLUMNSPECS' keywords are dynamically replaced.*/
  80     public $alter_column_sql = 'ALTER TABLE TABLENAME MODIFY COLUMN COLUMNSPECS';
  81
  82     /** @var string SQL sentence to drop one index where 'TABLENAME', 'INDEXNAME' keywords are dynamically replaced.*/
  83     public $drop_index_sql = 'ALTER TABLE TABLENAME DROP INDEX INDEXNAME';
  84
  85     /** @var string SQL sentence to rename one index where 'TABLENAME', 'OLDINDEXNAME' and 'NEWINDEXNAME' are dynamically replaced.*/
  86     public $rename_index_sql = null;
  87
  88     /** @var string SQL sentence to rename one key 'TABLENAME', 'OLDKEYNAME' and 'NEWKEYNAME' are dynamically replaced.*/
  89     public $rename_key_sql = null;
  90
  91     /** Maximum size of InnoDB row in Antelope file format */
  92     const ANTELOPE_MAX_ROW_SIZE = 8126;
  93
  94     /**
  95      * Reset a sequence to the id field of a table.
  96      *
  97      * @param xmldb_table|string $table name of table or the table object.
  98      * @return array of sql statements
  99      */
 100     public function getResetSequenceSQL($table) {
 101
 102         if ($table instanceof xmldb_table) {
 103             $tablename = $table->getName();
 104         } else {
 105             $tablename = $table;
 106         }
 107
 108         // From http://dev.mysql.com/doc/refman/5.0/en/alter-table.html
 109         $value = (int)$this->mdb->get_field_sql('SELECT MAX(id) FROM {'.$tablename.'}');
 110         $value++;
 111         return array("ALTER TABLE $this->prefix$tablename AUTO_INCREMENT = $value");
 112     }
 113
 114     /**
 115      * Calculate proximate row size when using InnoDB
 116      * tables in Antelope row format.
 117      *
 118      * Note: the returned value is a bit higher to compensate for
 119      *       errors and changes of column data types.
 120      *
 121      * @deprecated since Moodle 2.9 MDL-49723 - please do not use this function any more.
 122      * @param xmldb_field[]|database_column_info[] $columns
 123      * @return int approximate row size in bytes
 124      */
 125     public function guess_antolope_row_size(array $columns) {
 126         debugging('guess_antolope_row_size() is deprecated, please use guess_antelope_row_size() instead.', DEBUG_DEVELOPER);
 127         return $this->guess_antelope_row_size($columns);
 128     }
 129
 130     /**
 131      * Calculate proximate row size when using InnoDB tables in Antelope row format.
 132      *
 133      * Note: the returned value is a bit higher to compensate for errors and changes of column data types.
 134      *
 135      * @param xmldb_field[]|database_column_info[] $columns
 136      * @return int approximate row size in bytes
 137      */
 138     public function guess_antelope_row_size(array $columns) {
 139
 140         if (empty($columns)) {
 141             return 0;
 142         }
 143
 144         $size = 0;
 145         $first = reset($columns);
 146
 147         if (count($columns) > 1) {
 148             // Do not start with zero because we need to cover changes of field types and
 149             // this calculation is most probably not be accurate.
 150             $size += 1000;
 151         }
 152
 153         if ($first instanceof xmldb_field) {
 154             foreach ($columns as $field) {
 155                 switch ($field->getType()) {
 156                     case XMLDB_TYPE_TEXT:
 157                         $size += 768;
 158                         break;
 159                     case XMLDB_TYPE_BINARY:
 160                         $size += 768;
 161                         break;
 162                     case XMLDB_TYPE_CHAR:
 163                         $bytes = $field->getLength() * 3;
 164                         if ($bytes > 768) {
 165                             $bytes = 768;
 166                         }
 167                         $size += $bytes;
 168                         break;
 169                     default:
 170                         // Anything else is usually maximum 8 bytes.
 171                         $size += 8;
 172                 }
 173             }
 174
 175         } else if ($first instanceof database_column_info) {
 176             foreach ($columns as $column) {
 177                 switch ($column->meta_type) {
 178                     case 'X':
 179                         $size += 768;
 180                         break;
 181                     case 'B':
 182                         $size += 768;
 183                         break;
 184                     case 'C':
 185                         $bytes = $column->max_length * 3;
 186                         if ($bytes > 768) {
 187                             $bytes = 768;
 188                         }
 189                         $size += $bytes;
 190                         break;
 191                     default:
 192                         // Anything else is usually maximum 8 bytes.
 193                         $size += 8;
 194                 }
 195             }
 196         }
 197
 198         return $size;
 199     }
 200
 201     /**
 202      * Given one correct xmldb_table, returns the SQL statements
 203      * to create it (inside one array).
 204      *
 205      * @param xmldb_table $xmldb_table An xmldb_table instance.
 206      * @return array An array of SQL statements, starting with the table creation SQL followed
 207      * by any of its comments, indexes and sequence creation SQL statements.
 208      */
 209     public function getCreateTableSQL($xmldb_table) {
 210         // First find out if want some special db engine.
 211         $engine = $this->mdb->get_dbengine();
 212         // Do we know collation?
 213         $collation = $this->mdb->get_dbcollation();
 214
 215         // Do we need to use compressed format for rows?
 216         $rowformat = "";
 217         $size = $this->guess_antelope_row_size($xmldb_table->getFields());
 218         if ($size > self::ANTELOPE_MAX_ROW_SIZE) {
 219             if ($this->mdb->is_compressed_row_format_supported()) {
 220                 $rowformat = "\n ROW_FORMAT=Compressed";
 221             }
 222         }
 223
 224         $sqlarr = parent::getCreateTableSQL($xmldb_table);
 225
 226         // This is a very nasty hack that tries to use just one query per created table
 227         // because MySQL is stupidly slow when modifying empty tables.
 228         // Note: it is safer to inject everything on new lines because there might be some trailing -- comments.
 229         $sqls = array();
 230         $prevcreate = null;
 231         $matches = null;
 232         foreach ($sqlarr as $sql) {
 233             if (preg_match('/^CREATE TABLE ([^ ]+)/', $sql, $matches)) {
 234                 $prevcreate = $matches[1];
 235                 $sql = preg_replace('/\s*\)\s*$/s', '/*keyblock*/)', $sql);
 236                 // Let's inject the extra MySQL tweaks here.
 237                 if ($engine) {
 238                     $sql .= "\n ENGINE = $engine";
 239                 }
 240                 if ($collation) {
 241                     if (strpos($collation, 'utf8_') === 0) {
 242                         $sql .= "\n DEFAULT CHARACTER SET utf8";
 243                     }
 244                     $sql .= "\n DEFAULT COLLATE = $collation";
 245                 }
 246                 if ($rowformat) {
 247                     $sql .= $rowformat;
 248                 }
 249                 $sqls[] = $sql;
 250                 continue;
 251             }
 252             if ($prevcreate) {
 253                 if (preg_match('/^ALTER TABLE '.$prevcreate.' COMMENT=(.*)$/s', $sql, $matches)) {
 254                     $prev = array_pop($sqls);
 255                     $prev .= "\n COMMENT=$matches[1]";
 256                     $sqls[] = $prev;
 257                     continue;
 258                 }
 259                 if (preg_match('/^CREATE INDEX ([^ ]+) ON '.$prevcreate.' (.*)$/s', $sql, $matches)) {
 260                     $prev = array_pop($sqls);
 261                     if (strpos($prev, '/*keyblock*/')) {
 262                         $prev = str_replace('/*keyblock*/', "\n, KEY $matches[1] $matches[2]/*keyblock*/", $prev);
 263                         $sqls[] = $prev;
 264                         continue;
 265                     } else {
 266                         $sqls[] = $prev;
 267                     }
 268                 }
 269                 if (preg_match('/^CREATE UNIQUE INDEX ([^ ]+) ON '.$prevcreate.' (.*)$/s', $sql, $matches)) {
 270                     $prev = array_pop($sqls);
 271                     if (strpos($prev, '/*keyblock*/')) {
 272                         $prev = str_replace('/*keyblock*/', "\n, UNIQUE KEY $matches[1] $matches[2]/*keyblock*/", $prev);
 273                         $sqls[] = $prev;
 274                         continue;
 275                     } else {
 276                         $sqls[] = $prev;
 277                     }
 278                 }
 279             }
 280             $prevcreate = null;
 281             $sqls[] = $sql;
 282         }
 283
 284         foreach ($sqls as $key => $sql) {
 285             $sqls[$key] = str_replace('/*keyblock*/', "\n", $sql);
 286         }
 287
 288         return $sqls;
 289     }
 290
 291     /**
 292      * Given one xmldb_table and one xmldb_field, return the SQL statements needed to add the field to the table.
 293      *
 294      * @param xmldb_table $xmldb_table The table related to $xmldb_field.
 295      * @param xmldb_field $xmldb_field The instance of xmldb_field to create the SQL from.
 296      * @param string $skip_type_clause The type clause on alter columns, NULL by default.
 297      * @param string $skip_default_clause The default clause on alter columns, NULL by default.
 298      * @param string $skip_notnull_clause The null/notnull clause on alter columns, NULL by default.
 299      * @return array The SQL statement for adding a field to the table.
 300      */
 301     public function getAddFieldSQL($xmldb_table, $xmldb_field, $skip_type_clause = NULL, $skip_default_clause = NULL, $skip_notnull_clause = NULL) {
 302         $sqls = parent::getAddFieldSQL($xmldb_table, $xmldb_field, $skip_type_clause, $skip_default_clause, $skip_notnull_clause);
 303
 304         if ($this->table_exists($xmldb_table)) {
 305             $tablename = $xmldb_table->getName();
 306
 307             $size = $this->guess_antelope_row_size($this->mdb->get_columns($tablename));
 308             $size += $this->guess_antelope_row_size(array($xmldb_field));
 309
 310             if ($size > self::ANTELOPE_MAX_ROW_SIZE) {
 311                 if ($this->mdb->is_compressed_row_format_supported()) {
 312                     $format = strtolower($this->mdb->get_row_format($tablename));
 313                     if ($format === 'compact' or $format === 'redundant') {
 314                         // Change the format before conversion so that we do not run out of space.
 315                         array_unshift($sqls, "ALTER TABLE {$this->prefix}$tablename ROW_FORMAT=Compressed");
 316                     }
 317                 }
 318             }
 319         }
 320
 321         return $sqls;
 322     }
 323
 324     /**
 325      * Given one correct xmldb_table, returns the SQL statements
 326      * to create temporary table (inside one array).
 327      *
 328      * @param xmldb_table $xmldb_table The xmldb_table object instance.
 329      * @return array of sql statements
 330      */
 331     public function getCreateTempTableSQL($xmldb_table) {
 332         // Do we know collation?
 333         $collation = $this->mdb->get_dbcollation();
 334         $this->temptables->add_temptable($xmldb_table->getName());
 335
 336         $sqlarr = parent::getCreateTableSQL($xmldb_table);
 337
 338         // Let's inject the extra MySQL tweaks.
 339         foreach ($sqlarr as $i=>$sql) {
 340             if (strpos($sql, 'CREATE TABLE ') === 0) {
 341                 // We do not want the engine hack included in create table SQL.
 342                 $sqlarr[$i] = preg_replace('/^CREATE TABLE (.*)/s', 'CREATE TEMPORARY TABLE $1', $sql);
 343                 if ($collation) {
 344                     if (strpos($collation, 'utf8_') === 0) {
 345                         $sqlarr[$i] .= " DEFAULT CHARACTER SET utf8";
 346                     }
 347                     $sqlarr[$i] .= " DEFAULT COLLATE $collation";
 348                 }
 349             }
 350         }
 351
 352         return $sqlarr;
 353     }
 354
 355     /**
 356      * Given one correct xmldb_table, returns the SQL statements
 357      * to drop it (inside one array).
 358      *
 359      * @param xmldb_table $xmldb_table The table to drop.
 360      * @return array SQL statement(s) for dropping the specified table.
 361      */
 362     public function getDropTableSQL($xmldb_table) {
 363         $sqlarr = parent::getDropTableSQL($xmldb_table);
 364         if ($this->temptables->is_temptable($xmldb_table->getName())) {
 365             $sqlarr = preg_replace('/^DROP TABLE/', "DROP TEMPORARY TABLE", $sqlarr);
 366             $this->temptables->delete_temptable($xmldb_table->getName());
 367         }
 368         return $sqlarr;
 369     }
 370
 371     /**
 372      * Given one XMLDB Type, length and decimals, returns the DB proper SQL type.
 373      *
 374      * @param int $xmldb_type The xmldb_type defined constant. XMLDB_TYPE_INTEGER and other XMLDB_TYPE_* constants.
 375      * @param int $xmldb_length The length of that data type.
 376      * @param int $xmldb_decimals The decimal places of precision of the data type.
 377      * @return string The DB defined data type.
 378      */
 379     public function getTypeSQL($xmldb_type, $xmldb_length=null, $xmldb_decimals=null) {
 380
 381         switch ($xmldb_type) {
 382             case XMLDB_TYPE_INTEGER:    // From http://mysql.com/doc/refman/5.0/en/numeric-types.html!
 383                 if (empty($xmldb_length)) {
 384                     $xmldb_length = 10;
 385                 }
 386                 if ($xmldb_length > 9) {
 387                     $dbtype = 'BIGINT';
 388                 } else if ($xmldb_length > 6) {
 389                     $dbtype = 'INT';
 390                 } else if ($xmldb_length > 4) {
 391                     $dbtype = 'MEDIUMINT';
 392                 } else if ($xmldb_length > 2) {
 393                     $dbtype = 'SMALLINT';
 394                 } else {
 395                     $dbtype = 'TINYINT';
 396                 }
 397                 $dbtype .= '(' . $xmldb_length . ')';
 398                 break;
 399             case XMLDB_TYPE_NUMBER:
 400                 $dbtype = $this->number_type;
 401                 if (!empty($xmldb_length)) {
 402                     $dbtype .= '(' . $xmldb_length;
 403                     if (!empty($xmldb_decimals)) {
 404                         $dbtype .= ',' . $xmldb_decimals;
 405                     }
 406                     $dbtype .= ')';
 407                 }
 408                 break;
 409             case XMLDB_TYPE_FLOAT:
 410                 $dbtype = 'DOUBLE';
 411                 if (!empty($xmldb_decimals)) {
 412                     if ($xmldb_decimals < 6) {
 413                         $dbtype = 'FLOAT';
 414                     }
 415                 }
 416                 if (!empty($xmldb_length)) {
 417                     $dbtype .= '(' . $xmldb_length;
 418                     if (!empty($xmldb_decimals)) {
 419                         $dbtype .= ',' . $xmldb_decimals;
 420                     } else {
 421                         $dbtype .= ', 0'; // In MySQL, if length is specified, decimals are mandatory for FLOATs
 422                     }
 423                     $dbtype .= ')';
 424                 }
 425                 break;
 426             case XMLDB_TYPE_CHAR:
 427                 $dbtype = 'VARCHAR';
 428                 if (empty($xmldb_length)) {
 429                     $xmldb_length='255';
 430                 }
 431                 $dbtype .= '(' . $xmldb_length . ')';
 432                 if ($collation = $this->mdb->get_dbcollation()) {
 433                     if (strpos($collation, 'utf8_') === 0) {
 434                         $dbtype .= " CHARACTER SET utf8";
 435                     }
 436                     $dbtype .= " COLLATE $collation";
 437                 }
 438                 break;
 439             case XMLDB_TYPE_TEXT:
 440                 $dbtype = 'LONGTEXT';
 441                 if ($collation = $this->mdb->get_dbcollation()) {
 442                     if (strpos($collation, 'utf8_') === 0) {
 443                         $dbtype .= " CHARACTER SET utf8";
 444                     }
 445                     $dbtype .= " COLLATE $collation";
 446                 }
 447                 break;
 448             case XMLDB_TYPE_BINARY:
 449                 $dbtype = 'LONGBLOB';
 450                 break;
 451             case XMLDB_TYPE_DATETIME:
 452                 $dbtype = 'DATETIME';
 453         }
 454         return $dbtype;
 455     }
 456
 457     /**
 458      * Given one xmldb_table and one xmldb_field, return the SQL statements needed to add its default
 459      * (usually invoked from getModifyDefaultSQL()
 460      *
 461      * @param xmldb_table $xmldb_table The xmldb_table object instance.
 462      * @param xmldb_field $xmldb_field The xmldb_field object instance.
 463      * @return array Array of SQL statements to create a field's default.
 464      */
 465     public function getCreateDefaultSQL($xmldb_table, $xmldb_field) {
 466         // Just a wrapper over the getAlterFieldSQL() function for MySQL that
 467         // is capable of handling defaults
 468         return $this->getAlterFieldSQL($xmldb_table, $xmldb_field);
 469     }
 470
 471     /**
 472      * Given one correct xmldb_field and the new name, returns the SQL statements
 473      * to rename it (inside one array).
 474      *
 475      * @param xmldb_table $xmldb_table The table related to $xmldb_field.
 476      * @param xmldb_field $xmldb_field The instance of xmldb_field to get the renamed field from.
 477      * @param string $newname The new name to rename the field to.
 478      * @return array The SQL statements for renaming the field.
 479      */
 480     public function getRenameFieldSQL($xmldb_table, $xmldb_field, $newname) {
 481         // NOTE: MySQL is pretty different from the standard to justify this overloading.
 482
 483         // Need a clone of xmldb_field to perform the change leaving original unmodified
 484         $xmldb_field_clone = clone($xmldb_field);
 485
 486         // Change the name of the field to perform the change
 487         $xmldb_field_clone->setName($newname);
 488
 489         $fieldsql = $this->getFieldSQL($xmldb_table, $xmldb_field_clone);
 490
 491         $sql = 'ALTER TABLE ' . $this->getTableName($xmldb_table) . ' CHANGE ' .
 492                $xmldb_field->getName() . ' ' . $fieldsql;
 493
 494         return array($sql);
 495     }
 496
 497     /**
 498      * Given one xmldb_table and one xmldb_field, return the SQL statements needed to drop its default
 499      * (usually invoked from getModifyDefaultSQL()
 500      *
 501      * Note that this method may be dropped in future.
 502      *
 503      * @param xmldb_table $xmldb_table The xmldb_table object instance.
 504      * @param xmldb_field $xmldb_field The xmldb_field object instance.
 505      * @return array Array of SQL statements to create a field's default.
 506      *
 507      * @todo MDL-31147 Moodle 2.1 - Drop getDropDefaultSQL()
 508      */
 509     public function getDropDefaultSQL($xmldb_table, $xmldb_field) {
 510         // Just a wrapper over the getAlterFieldSQL() function for MySQL that
 511         // is capable of handling defaults
 512         return $this->getAlterFieldSQL($xmldb_table, $xmldb_field);
 513     }
 514
 515     /**
 516      * Returns the code (array of statements) needed to add one comment to the table.
 517      *
 518      * @param xmldb_table $xmldb_table The xmldb_table object instance.
 519      * @return array Array of SQL statements to add one comment to the table.
 520      */
 521     function getCommentSQL ($xmldb_table) {
 522         $comment = '';
 523
 524         if ($xmldb_table->getComment()) {
 525             $comment .= 'ALTER TABLE ' . $this->getTableName($xmldb_table);
 526             $comment .= " COMMENT='" . $this->addslashes(substr($xmldb_table->getComment(), 0, 60)) . "'";
 527         }
 528         return array($comment);
 529     }
 530
 531     /**
 532      * Given one object name and it's type (pk, uk, fk, ck, ix, uix, seq, trg).
 533      *
 534      * (MySQL requires the whole xmldb_table object to be specified, so we add it always)
 535      *
 536      * This is invoked from getNameForObject().
 537      * Only some DB have this implemented.
 538      *
 539      * @param string $object_name The object's name to check for.
 540      * @param string $type The object's type (pk, uk, fk, ck, ix, uix, seq, trg).
 541      * @param string $table_name The table's name to check in
 542      * @return bool If such name is currently in use (true) or no (false)
 543      */
 544     public function isNameInUse($object_name, $type, $table_name) {
 545
 546         switch($type) {
 547             case 'ix':
 548             case 'uix':
 549                 // First of all, check table exists
 550                 $metatables = $this->mdb->get_tables();
 551                 if (isset($metatables[$table_name])) {
 552                     // Fetch all the indexes in the table
 553                     if ($indexes = $this->mdb->get_indexes($table_name)) {
 554                         // Look for existing index in array
 555                         if (isset($indexes[$object_name])) {
 556                             return true;
 557                         }
 558                     }
 559                 }
 560                 break;
 561         }
 562         return false; //No name in use found
 563     }
 564
 565
 566     /**
 567      * Returns an array of reserved words (lowercase) for this DB
 568      * @return array An array of database specific reserved words
 569      */
 570     public static function getReservedWords() {
 571         // This file contains the reserved words for MySQL databases
 572         // from http://dev.mysql.com/doc/refman/6.0/en/reserved-words.html
 573         $reserved_words = array (
 574             'accessible', 'add', 'all', 'alter', 'analyze', 'and', 'as', 'asc',
 575             'asensitive', 'before', 'between', 'bigint', 'binary',
 576             'blob', 'both', 'by', 'call', 'cascade', 'case', 'change',
 577             'char', 'character', 'check', 'collate', 'column',
 578             'condition', 'connection', 'constraint', 'continue',
 579             'convert', 'create', 'cross', 'current_date', 'current_time',
 580             'current_timestamp', 'current_user', 'cursor', 'database',
 581             'databases', 'day_hour', 'day_microsecond',
 582             'day_minute', 'day_second', 'dec', 'decimal', 'declare',
 583             'default', 'delayed', 'delete', 'desc', 'describe',
 584             'deterministic', 'distinct', 'distinctrow', 'div', 'double',
 585             'drop', 'dual', 'each', 'else', 'elseif', 'enclosed', 'escaped',
 586             'exists', 'exit', 'explain', 'false', 'fetch', 'float', 'float4',
 587             'float8', 'for', 'force', 'foreign', 'from', 'fulltext', 'grant',
 588             'group', 'having', 'high_priority', 'hour_microsecond',
 589             'hour_minute', 'hour_second', 'if', 'ignore', 'in', 'index',
 590             'infile', 'inner', 'inout', 'insensitive', 'insert', 'int', 'int1',
 591             'int2', 'int3', 'int4', 'int8', 'integer', 'interval', 'into', 'is',
 592             'iterate', 'join', 'key', 'keys', 'kill', 'leading', 'leave', 'left',
 593             'like', 'limit', 'linear', 'lines', 'load', 'localtime', 'localtimestamp',
 594             'lock', 'long', 'longblob', 'longtext', 'loop', 'low_priority', 'master_heartbeat_period',
 595             'master_ssl_verify_server_cert', 'match', 'mediumblob', 'mediumint', 'mediumtext',
 596             'middleint', 'minute_microsecond', 'minute_second',
 597             'mod', 'modifies', 'natural', 'not', 'no_write_to_binlog',
 598             'null', 'numeric', 'on', 'optimize', 'option', 'optionally',
 599             'or', 'order', 'out', 'outer', 'outfile', 'overwrite', 'precision', 'primary',
 600             'procedure', 'purge', 'raid0', 'range', 'read', 'read_only', 'read_write', 'reads', 'real',
 601             'references', 'regexp', 'release', 'rename', 'repeat', 'replace',
 602             'require', 'restrict', 'return', 'revoke', 'right', 'rlike', 'schema',
 603             'schemas', 'second_microsecond', 'select', 'sensitive',
 604             'separator', 'set', 'show', 'smallint', 'soname', 'spatial',
 605             'specific', 'sql', 'sqlexception', 'sqlstate', 'sqlwarning',
 606             'sql_big_result', 'sql_calc_found_rows', 'sql_small_result',
 607             'ssl', 'starting', 'straight_join', 'table', 'terminated', 'then',
 608             'tinyblob', 'tinyint', 'tinytext', 'to', 'trailing', 'trigger', 'true',
 609             'undo', 'union', 'unique', 'unlock', 'unsigned', 'update',
 610             'upgrade', 'usage', 'use', 'using', 'utc_date', 'utc_time',
 611             'utc_timestamp', 'values', 'varbinary', 'varchar', 'varcharacter',
 612             'varying', 'when', 'where', 'while', 'with', 'write', 'x509',
 613             'xor', 'year_month', 'zerofill'
 614         );
 615         return $reserved_words;
 616     }
 617 }