includes/libs/rdbms/database/DatabaseMssql.php

   1 <?php
   2 /**
   3  * This is the MS SQL Server Native database abstraction layer.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  * @author Joel Penner <a-joelpe at microsoft dot com>
  23  * @author Chris Pucci <a-cpucci at microsoft dot com>
  24  * @author Ryan Biesemeyer <v-ryanbi at microsoft dot com>
  25  * @author Ryan Schmidt <skizzerz at gmail dot com>
  26  */
  27
  28 namespace Wikimedia\Rdbms;
  29
  30 use Wikimedia;
  31 use Exception;
  32 use stdClass;
  33
  34 /**
  35  * @ingroup Database
  36  */
  37 class DatabaseMssql extends Database {
  38         /** @var int */
  39         protected $serverPort;
  40         /** @var bool */
  41         protected $useWindowsAuth = false;
  42         /** @var int|null */
  43         protected $lastInsertId = null;
  44         /** @var int|null */
  45         protected $lastAffectedRowCount = null;
  46         /** @var int */
  47         protected $subqueryId = 0;
  48         /** @var bool */
  49         protected $scrollableCursor = true;
  50         /** @var bool */
  51         protected $prepareStatements = true;
  52         /** @var stdClass[][]|null */
  53         protected $binaryColumnCache = null;
  54         /** @var stdClass[][]|null */
  55         protected $bitColumnCache = null;
  56         /** @var bool */
  57         protected $ignoreDupKeyErrors = false;
  58         /** @var string[] */
  59         protected $ignoreErrors = [];
  60
  61         public function implicitGroupby() {
  62                 return false;
  63         }
  64
  65         public function implicitOrderby() {
  66                 return false;
  67         }
  68
  69         public function unionSupportsOrderAndLimit() {
  70                 return false;
  71         }
  72
  73         public function __construct( array $params ) {
  74                 $this->serverPort = $params['port'];
  75                 $this->useWindowsAuth = $params['UseWindowsAuth'];
  76
  77                 parent::__construct( $params );
  78         }
  79
  80         /**
  81          * Usually aborts on failure
  82          * @param string $server
  83          * @param string $user
  84          * @param string $password
  85          * @param string $dbName
  86          * @throws DBConnectionError
  87          * @return bool|resource|null
  88          */
  89         public function open( $server, $user, $password, $dbName ) {
  90                 # Test for driver support, to avoid suppressed fatal error
  91                 if ( !function_exists( 'sqlsrv_connect' ) ) {
  92                         throw new DBConnectionError(
  93                                 $this,
  94                                 "Microsoft SQL Server Native (sqlsrv) functions missing.
  95                                 You can download the driver from: http://go.microsoft.com/fwlink/?LinkId=123470\n"
  96                         );
  97                 }
  98
  99                 # e.g. the class is being loaded
 100                 if ( !strlen( $user ) ) {
 101                         return null;
 102                 }
 103
 104                 $this->close();
 105                 $this->server = $server;
 106                 $this->user = $user;
 107                 $this->password = $password;
 108                 $this->dbName = $dbName;
 109
 110                 $connectionInfo = [];
 111
 112                 if ( $dbName ) {
 113                         $connectionInfo['Database'] = $dbName;
 114                 }
 115
 116                 // Decide which auth scenerio to use
 117                 // if we are using Windows auth, then don't add credentials to $connectionInfo
 118                 if ( !$this->useWindowsAuth ) {
 119                         $connectionInfo['UID'] = $user;
 120                         $connectionInfo['PWD'] = $password;
 121                 }
 122
 123                 Wikimedia\suppressWarnings();
 124                 $this->conn = sqlsrv_connect( $server, $connectionInfo );
 125                 Wikimedia\restoreWarnings();
 126
 127                 if ( $this->conn === false ) {
 128                         throw new DBConnectionError( $this, $this->lastError() );
 129                 }
 130
 131                 $this->opened = true;
 132
 133                 return $this->conn;
 134         }
 135
 136         /**
 137          * Closes a database connection, if it is open
 138          * Returns success, true if already closed
 139          * @return bool
 140          */
 141         protected function closeConnection() {
 142                 return sqlsrv_close( $this->conn );
 143         }
 144
 145         /**
 146          * @param bool|MssqlResultWrapper|resource $result
 147          * @return bool|MssqlResultWrapper
 148          */
 149         protected function resultObject( $result ) {
 150                 if ( !$result ) {
 151                         return false;
 152                 } elseif ( $result instanceof MssqlResultWrapper ) {
 153                         return $result;
 154                 } elseif ( $result === true ) {
 155                         // Successful write query
 156                         return $result;
 157                 } else {
 158                         return new MssqlResultWrapper( $this, $result );
 159                 }
 160         }
 161
 162         /**
 163          * @param string $sql
 164          * @return bool|MssqlResultWrapper|resource
 165          * @throws DBUnexpectedError
 166          */
 167         protected function doQuery( $sql ) {
 168                 // several extensions seem to think that all databases support limits
 169                 // via LIMIT N after the WHERE clause, but  MSSQL uses SELECT TOP N,
 170                 // so to catch any of those extensions we'll do a quick check for a
 171                 // LIMIT clause and pass $sql through $this->LimitToTopN() which parses
 172                 // the LIMIT clause and passes the result to $this->limitResult();
 173                 if ( preg_match( '/\bLIMIT\s*/i', $sql ) ) {
 174                         // massage LIMIT -> TopN
 175                         $sql = $this->LimitToTopN( $sql );
 176                 }
 177
 178                 // MSSQL doesn't have EXTRACT(epoch FROM XXX)
 179                 if ( preg_match( '#\bEXTRACT\s*?\(\s*?EPOCH\s+FROM\b#i', $sql, $matches ) ) {
 180                         // This is same as UNIX_TIMESTAMP, we need to calc # of seconds from 1970
 181                         $sql = str_replace( $matches[0], "DATEDIFF(s,CONVERT(datetime,'1/1/1970'),", $sql );
 182                 }
 183
 184                 // perform query
 185
 186                 // SQLSRV_CURSOR_STATIC is slower than SQLSRV_CURSOR_CLIENT_BUFFERED (one of the two is
 187                 // needed if we want to be able to seek around the result set), however CLIENT_BUFFERED
 188                 // has a bug in the sqlsrv driver where wchar_t types (such as nvarchar) that are empty
 189                 // strings make php throw a fatal error "Severe error translating Unicode"
 190                 if ( $this->scrollableCursor ) {
 191                         $scrollArr = [ 'Scrollable' => SQLSRV_CURSOR_STATIC ];
 192                 } else {
 193                         $scrollArr = [];
 194                 }
 195
 196                 if ( $this->prepareStatements ) {
 197                         // we do prepare + execute so we can get its field metadata for later usage if desired
 198                         $stmt = sqlsrv_prepare( $this->conn, $sql, [], $scrollArr );
 199                         $success = sqlsrv_execute( $stmt );
 200                 } else {
 201                         $stmt = sqlsrv_query( $this->conn, $sql, [], $scrollArr );
 202                         $success = (bool)$stmt;
 203                 }
 204
 205                 // Make a copy to ensure what we add below does not get reflected in future queries
 206                 $ignoreErrors = $this->ignoreErrors;
 207
 208                 if ( $this->ignoreDupKeyErrors ) {
 209                         // ignore duplicate key errors
 210                         // this emulates INSERT IGNORE in MySQL
 211                         $ignoreErrors[] = '2601'; // duplicate key error caused by unique index
 212                         $ignoreErrors[] = '2627'; // duplicate key error caused by primary key
 213                         $ignoreErrors[] = '3621'; // generic "the statement has been terminated" error
 214                 }
 215
 216                 if ( $success === false ) {
 217                         $errors = sqlsrv_errors();
 218                         $success = true;
 219
 220                         foreach ( $errors as $err ) {
 221                                 if ( !in_array( $err['code'], $ignoreErrors ) ) {
 222                                         $success = false;
 223                                         break;
 224                                 }
 225                         }
 226
 227                         if ( $success === false ) {
 228                                 return false;
 229                         }
 230                 }
 231                 // remember number of rows affected
 232                 $this->lastAffectedRowCount = sqlsrv_rows_affected( $stmt );
 233
 234                 return $stmt;
 235         }
 236
 237         public function freeResult( $res ) {
 238                 if ( $res instanceof ResultWrapper ) {
 239                         $res = $res->result;
 240                 }
 241
 242                 sqlsrv_free_stmt( $res );
 243         }
 244
 245         /**
 246          * @param MssqlResultWrapper $res
 247          * @return stdClass
 248          */
 249         public function fetchObject( $res ) {
 250                 // $res is expected to be an instance of MssqlResultWrapper here
 251                 return $res->fetchObject();
 252         }
 253
 254         /**
 255          * @param MssqlResultWrapper $res
 256          * @return array
 257          */
 258         public function fetchRow( $res ) {
 259                 return $res->fetchRow();
 260         }
 261
 262         /**
 263          * @param mixed $res
 264          * @return int
 265          */
 266         public function numRows( $res ) {
 267                 if ( $res instanceof ResultWrapper ) {
 268                         $res = $res->result;
 269                 }
 270
 271                 $ret = sqlsrv_num_rows( $res );
 272
 273                 if ( $ret === false ) {
 274                         // we cannot get an amount of rows from this cursor type
 275                         // has_rows returns bool true/false if the result has rows
 276                         $ret = (int)sqlsrv_has_rows( $res );
 277                 }
 278
 279                 return $ret;
 280         }
 281
 282         /**
 283          * @param mixed $res
 284          * @return int
 285          */
 286         public function numFields( $res ) {
 287                 if ( $res instanceof ResultWrapper ) {
 288                         $res = $res->result;
 289                 }
 290
 291                 return sqlsrv_num_fields( $res );
 292         }
 293
 294         /**
 295          * @param mixed $res
 296          * @param int $n
 297          * @return int
 298          */
 299         public function fieldName( $res, $n ) {
 300                 if ( $res instanceof ResultWrapper ) {
 301                         $res = $res->result;
 302                 }
 303
 304                 return sqlsrv_field_metadata( $res )[$n]['Name'];
 305         }
 306
 307         /**
 308          * This must be called after nextSequenceVal
 309          * @return int|null
 310          */
 311         public function insertId() {
 312                 return $this->lastInsertId;
 313         }
 314
 315         /**
 316          * @param MssqlResultWrapper $res
 317          * @param int $row
 318          * @return bool
 319          */
 320         public function dataSeek( $res, $row ) {
 321                 return $res->seek( $row );
 322         }
 323
 324         /**
 325          * @return string
 326          */
 327         public function lastError() {
 328                 $strRet = '';
 329                 $retErrors = sqlsrv_errors( SQLSRV_ERR_ALL );
 330                 if ( $retErrors != null ) {
 331                         foreach ( $retErrors as $arrError ) {
 332                                 $strRet .= $this->formatError( $arrError ) . "\n";
 333                         }
 334                 } else {
 335                         $strRet = "No errors found";
 336                 }
 337
 338                 return $strRet;
 339         }
 340
 341         /**
 342          * @param array $err
 343          * @return string
 344          */
 345         private function formatError( $err ) {
 346                 return '[SQLSTATE ' .
 347                         $err['SQLSTATE'] . '][Error Code ' . $err['code'] . ']' . $err['message'];
 348         }
 349
 350         /**
 351          * @return string|int
 352          */
 353         public function lastErrno() {
 354                 $err = sqlsrv_errors( SQLSRV_ERR_ALL );
 355                 if ( $err !== null && isset( $err[0] ) ) {
 356                         return $err[0]['code'];
 357                 } else {
 358                         return 0;
 359                 }
 360         }
 361
 362         /**
 363          * @return int
 364          */
 365         protected function fetchAffectedRowCount() {
 366                 return $this->lastAffectedRowCount;
 367         }
 368
 369         /**
 370          * SELECT wrapper
 371          *
 372          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 373          * @param mixed $vars Array or string, field name(s) to be retrieved
 374          * @param mixed $conds Array or string, condition(s) for WHERE
 375          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 376          * @param array $options Associative array of options (e.g.
 377          *   [ 'GROUP BY' => 'page_title' ]), see Database::makeSelectOptions
 378          *   code for list of supported stuff
 379          * @param array $join_conds Associative array of table join conditions
 380          *   (optional) (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 381          * @return mixed Database result resource (feed to Database::fetchObject
 382          *   or whatever), or false on failure
 383          * @throws DBQueryError
 384          * @throws DBUnexpectedError
 385          * @throws Exception
 386          */
 387         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
 388                 $options = [], $join_conds = []
 389         ) {
 390                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 391                 if ( isset( $options['EXPLAIN'] ) ) {
 392                         try {
 393                                 $this->scrollableCursor = false;
 394                                 $this->prepareStatements = false;
 395                                 $this->query( "SET SHOWPLAN_ALL ON" );
 396                                 $ret = $this->query( $sql, $fname );
 397                                 $this->query( "SET SHOWPLAN_ALL OFF" );
 398                         } catch ( DBQueryError $dqe ) {
 399                                 if ( isset( $options['FOR COUNT'] ) ) {
 400                                         // likely don't have privs for SHOWPLAN, so run a select count instead
 401                                         $this->query( "SET SHOWPLAN_ALL OFF" );
 402                                         unset( $options['EXPLAIN'] );
 403                                         $ret = $this->select(
 404                                                 $table,
 405                                                 'COUNT(*) AS EstimateRows',
 406                                                 $conds,
 407                                                 $fname,
 408                                                 $options,
 409                                                 $join_conds
 410                                         );
 411                                 } else {
 412                                         // someone actually wanted the query plan instead of an est row count
 413                                         // let them know of the error
 414                                         $this->scrollableCursor = true;
 415                                         $this->prepareStatements = true;
 416                                         throw $dqe;
 417                                 }
 418                         }
 419                         $this->scrollableCursor = true;
 420                         $this->prepareStatements = true;
 421                         return $ret;
 422                 }
 423                 return $this->query( $sql, $fname );
 424         }
 425
 426         /**
 427          * SELECT wrapper
 428          *
 429          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 430          * @param mixed $vars Array or string, field name(s) to be retrieved
 431          * @param mixed $conds Array or string, condition(s) for WHERE
 432          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 433          * @param array $options Associative array of options (e.g. [ 'GROUP BY' => 'page_title' ]),
 434          *   see Database::makeSelectOptions code for list of supported stuff
 435          * @param array $join_conds Associative array of table join conditions (optional)
 436          *    (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 437          * @return string The SQL text
 438          */
 439         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
 440                 $options = [], $join_conds = []
 441         ) {
 442                 if ( isset( $options['EXPLAIN'] ) ) {
 443                         unset( $options['EXPLAIN'] );
 444                 }
 445
 446                 $sql = parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 447
 448                 // try to rewrite aggregations of bit columns (currently MAX and MIN)
 449                 if ( strpos( $sql, 'MAX(' ) !== false || strpos( $sql, 'MIN(' ) !== false ) {
 450                         $bitColumns = [];
 451                         if ( is_array( $table ) ) {
 452                                 $tables = $table;
 453                                 while ( $tables ) {
 454                                         $t = array_pop( $tables );
 455                                         if ( is_array( $t ) ) {
 456                                                 $tables = array_merge( $tables, $t );
 457                                         } else {
 458                                                 $bitColumns += $this->getBitColumns( $this->tableName( $t ) );
 459                                         }
 460                                 }
 461                         } else {
 462                                 $bitColumns = $this->getBitColumns( $this->tableName( $table ) );
 463                         }
 464
 465                         foreach ( $bitColumns as $col => $info ) {
 466                                 $replace = [
 467                                         "MAX({$col})" => "MAX(CAST({$col} AS tinyint))",
 468                                         "MIN({$col})" => "MIN(CAST({$col} AS tinyint))",
 469                                 ];
 470                                 $sql = str_replace( array_keys( $replace ), array_values( $replace ), $sql );
 471                         }
 472                 }
 473
 474                 return $sql;
 475         }
 476
 477         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
 478                 $fname = __METHOD__
 479         ) {
 480                 $this->scrollableCursor = false;
 481                 try {
 482                         parent::deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname );
 483                 } catch ( Exception $e ) {
 484                         $this->scrollableCursor = true;
 485                         throw $e;
 486                 }
 487                 $this->scrollableCursor = true;
 488         }
 489
 490         public function delete( $table, $conds, $fname = __METHOD__ ) {
 491                 $this->scrollableCursor = false;
 492                 try {
 493                         parent::delete( $table, $conds, $fname );
 494                 } catch ( Exception $e ) {
 495                         $this->scrollableCursor = true;
 496                         throw $e;
 497                 }
 498                 $this->scrollableCursor = true;
 499         }
 500
 501         /**
 502          * Estimate rows in dataset
 503          * Returns estimated count, based on SHOWPLAN_ALL output
 504          * This is not necessarily an accurate estimate, so use sparingly
 505          * Returns -1 if count cannot be found
 506          * Takes same arguments as Database::select()
 507          * @param string $table
 508          * @param string $vars
 509          * @param string $conds
 510          * @param string $fname
 511          * @param array $options
 512          * @return int
 513          */
 514         public function estimateRowCount( $table, $vars = '*', $conds = '',
 515                 $fname = __METHOD__, $options = []
 516         ) {
 517                 // http://msdn2.microsoft.com/en-us/library/aa259203.aspx
 518                 $options['EXPLAIN'] = true;
 519                 $options['FOR COUNT'] = true;
 520                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 521
 522                 $rows = -1;
 523                 if ( $res ) {
 524                         $row = $this->fetchRow( $res );
 525
 526                         if ( isset( $row['EstimateRows'] ) ) {
 527                                 $rows = (int)$row['EstimateRows'];
 528                         }
 529                 }
 530
 531                 return $rows;
 532         }
 533
 534         /**
 535          * Returns information about an index
 536          * If errors are explicitly ignored, returns NULL on failure
 537          * @param string $table
 538          * @param string $index
 539          * @param string $fname
 540          * @return array|bool|null
 541          */
 542         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 543                 # This does not return the same info as MYSQL would, but that's OK
 544                 # because MediaWiki never uses the returned value except to check for
 545                 # the existence of indexes.
 546                 $sql = "sp_helpindex '" . $this->tableName( $table ) . "'";
 547                 $res = $this->query( $sql, $fname );
 548
 549                 if ( !$res ) {
 550                         return null;
 551                 }
 552
 553                 $result = [];
 554                 foreach ( $res as $row ) {
 555                         if ( $row->index_name == $index ) {
 556                                 $row->Non_unique = !stristr( $row->index_description, "unique" );
 557                                 $cols = explode( ", ", $row->index_keys );
 558                                 foreach ( $cols as $col ) {
 559                                         $row->Column_name = trim( $col );
 560                                         $result[] = clone $row;
 561                                 }
 562                         } elseif ( $index == 'PRIMARY' && stristr( $row->index_description, 'PRIMARY' ) ) {
 563                                 $row->Non_unique = 0;
 564                                 $cols = explode( ", ", $row->index_keys );
 565                                 foreach ( $cols as $col ) {
 566                                         $row->Column_name = trim( $col );
 567                                         $result[] = clone $row;
 568                                 }
 569                         }
 570                 }
 571
 572                 return empty( $result ) ? false : $result;
 573         }
 574
 575         /**
 576          * INSERT wrapper, inserts an array into a table
 577          *
 578          * $arrToInsert may be a single associative array, or an array of these with numeric keys, for
 579          * multi-row insert.
 580          *
 581          * Usually aborts on failure
 582          * If errors are explicitly ignored, returns success
 583          * @param string $table
 584          * @param array $arrToInsert
 585          * @param string $fname
 586          * @param array $options
 587          * @return bool
 588          * @throws Exception
 589          */
 590         public function insert( $table, $arrToInsert, $fname = __METHOD__, $options = [] ) {
 591                 # No rows to insert, easy just return now
 592                 if ( !count( $arrToInsert ) ) {
 593                         return true;
 594                 }
 595
 596                 if ( !is_array( $options ) ) {
 597                         $options = [ $options ];
 598                 }
 599
 600                 $table = $this->tableName( $table );
 601
 602                 if ( !( isset( $arrToInsert[0] ) && is_array( $arrToInsert[0] ) ) ) { // Not multi row
 603                         $arrToInsert = [ 0 => $arrToInsert ]; // make everything multi row compatible
 604                 }
 605
 606                 // We know the table we're inserting into, get its identity column
 607                 $identity = null;
 608                 // strip matching square brackets and the db/schema from table name
 609                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
 610                 $tableRaw = array_pop( $tableRawArr );
 611                 $res = $this->doQuery(
 612                         "SELECT NAME AS idColumn FROM SYS.IDENTITY_COLUMNS " .
 613                                 "WHERE OBJECT_NAME(OBJECT_ID)='{$tableRaw}'"
 614                 );
 615                 if ( $res && sqlsrv_has_rows( $res ) ) {
 616                         // There is an identity for this table.
 617                         $identityArr = sqlsrv_fetch_array( $res, SQLSRV_FETCH_ASSOC );
 618                         $identity = array_pop( $identityArr );
 619                 }
 620                 sqlsrv_free_stmt( $res );
 621
 622                 // Determine binary/varbinary fields so we can encode data as a hex string like 0xABCDEF
 623                 $binaryColumns = $this->getBinaryColumns( $table );
 624
 625                 // INSERT IGNORE is not supported by SQL Server
 626                 // remove IGNORE from options list and set ignore flag to true
 627                 if ( in_array( 'IGNORE', $options ) ) {
 628                         $options = array_diff( $options, [ 'IGNORE' ] );
 629                         $this->ignoreDupKeyErrors = true;
 630                 }
 631
 632                 $ret = null;
 633                 foreach ( $arrToInsert as $a ) {
 634                         // start out with empty identity column, this is so we can return
 635                         // it as a result of the INSERT logic
 636                         $sqlPre = '';
 637                         $sqlPost = '';
 638                         $identityClause = '';
 639
 640                         // if we have an identity column
 641                         if ( $identity ) {
 642                                 // iterate through
 643                                 foreach ( $a as $k => $v ) {
 644                                         if ( $k == $identity ) {
 645                                                 if ( !is_null( $v ) ) {
 646                                                         // there is a value being passed to us,
 647                                                         // we need to turn on and off inserted identity
 648                                                         $sqlPre = "SET IDENTITY_INSERT $table ON;";
 649                                                         $sqlPost = ";SET IDENTITY_INSERT $table OFF;";
 650                                                 } else {
 651                                                         // we can't insert NULL into an identity column,
 652                                                         // so remove the column from the insert.
 653                                                         unset( $a[$k] );
 654                                                 }
 655                                         }
 656                                 }
 657
 658                                 // we want to output an identity column as result
 659                                 $identityClause = "OUTPUT INSERTED.$identity ";
 660                         }
 661
 662                         $keys = array_keys( $a );
 663
 664                         // Build the actual query
 665                         $sql = $sqlPre . 'INSERT ' . implode( ' ', $options ) .
 666                                 " INTO $table (" . implode( ',', $keys ) . ") $identityClause VALUES (";
 667
 668                         $first = true;
 669                         foreach ( $a as $key => $value ) {
 670                                 if ( isset( $binaryColumns[$key] ) ) {
 671                                         $value = new MssqlBlob( $value );
 672                                 }
 673                                 if ( $first ) {
 674                                         $first = false;
 675                                 } else {
 676                                         $sql .= ',';
 677                                 }
 678                                 if ( is_null( $value ) ) {
 679                                         $sql .= 'null';
 680                                 } elseif ( is_array( $value ) || is_object( $value ) ) {
 681                                         if ( is_object( $value ) && $value instanceof Blob ) {
 682                                                 $sql .= $this->addQuotes( $value );
 683                                         } else {
 684                                                 $sql .= $this->addQuotes( serialize( $value ) );
 685                                         }
 686                                 } else {
 687                                         $sql .= $this->addQuotes( $value );
 688                                 }
 689                         }
 690                         $sql .= ')' . $sqlPost;
 691
 692                         // Run the query
 693                         $this->scrollableCursor = false;
 694                         try {
 695                                 $ret = $this->query( $sql );
 696                         } catch ( Exception $e ) {
 697                                 $this->scrollableCursor = true;
 698                                 $this->ignoreDupKeyErrors = false;
 699                                 throw $e;
 700                         }
 701                         $this->scrollableCursor = true;
 702
 703                         if ( $ret instanceof ResultWrapper && !is_null( $identity ) ) {
 704                                 // Then we want to get the identity column value we were assigned and save it off
 705                                 $row = $ret->fetchObject();
 706                                 if ( is_object( $row ) ) {
 707                                         $this->lastInsertId = $row->$identity;
 708                                         // It seems that mAffectedRows is -1 sometimes when OUTPUT INSERTED.identity is
 709                                         // used if we got an identity back, we know for sure a row was affected, so
 710                                         // adjust that here
 711                                         if ( $this->lastAffectedRowCount == -1 ) {
 712                                                 $this->lastAffectedRowCount = 1;
 713                                         }
 714                                 }
 715                         }
 716                 }
 717
 718                 $this->ignoreDupKeyErrors = false;
 719
 720                 return $ret;
 721         }
 722
 723         /**
 724          * INSERT SELECT wrapper
 725          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 726          * Source items may be literals rather than field names, but strings should
 727          * be quoted with Database::addQuotes().
 728          * @param string $destTable
 729          * @param array|string $srcTable May be an array of tables.
 730          * @param array $varMap
 731          * @param array $conds May be "*" to copy the whole table.
 732          * @param string $fname
 733          * @param array $insertOptions
 734          * @param array $selectOptions
 735          * @param array $selectJoinConds
 736          * @return bool
 737          * @throws Exception
 738          */
 739         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 740                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
 741         ) {
 742                 $this->scrollableCursor = false;
 743                 try {
 744                         $ret = parent::nativeInsertSelect(
 745                                 $destTable,
 746                                 $srcTable,
 747                                 $varMap,
 748                                 $conds,
 749                                 $fname,
 750                                 $insertOptions,
 751                                 $selectOptions,
 752                                 $selectJoinConds
 753                         );
 754                 } catch ( Exception $e ) {
 755                         $this->scrollableCursor = true;
 756                         throw $e;
 757                 }
 758                 $this->scrollableCursor = true;
 759
 760                 return $ret;
 761         }
 762
 763         /**
 764          * UPDATE wrapper. Takes a condition array and a SET array.
 765          *
 766          * @param string $table Name of the table to UPDATE. This will be passed through
 767          *                Database::tableName().
 768          *
 769          * @param array $values An array of values to SET. For each array element,
 770          *                the key gives the field name, and the value gives the data
 771          *                to set that field to. The data will be quoted by
 772          *                Database::addQuotes().
 773          *
 774          * @param array $conds An array of conditions (WHERE). See
 775          *                Database::select() for the details of the format of
 776          *                condition arrays. Use '*' to update all rows.
 777          *
 778          * @param string $fname The function name of the caller (from __METHOD__),
 779          *                for logging and profiling.
 780          *
 781          * @param array $options An array of UPDATE options, can be:
 782          *                   - IGNORE: Ignore unique key conflicts
 783          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
 784          * @return bool
 785          * @throws DBUnexpectedError
 786          * @throws Exception
 787          */
 788         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
 789                 $table = $this->tableName( $table );
 790                 $binaryColumns = $this->getBinaryColumns( $table );
 791
 792                 $opts = $this->makeUpdateOptions( $options );
 793                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET, $binaryColumns );
 794
 795                 if ( $conds !== [] && $conds !== '*' ) {
 796                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND, $binaryColumns );
 797                 }
 798
 799                 $this->scrollableCursor = false;
 800                 try {
 801                         $this->query( $sql );
 802                 } catch ( Exception $e ) {
 803                         $this->scrollableCursor = true;
 804                         throw $e;
 805                 }
 806                 $this->scrollableCursor = true;
 807                 return true;
 808         }
 809
 810         /**
 811          * Makes an encoded list of strings from an array
 812          * @param array $a Containing the data
 813          * @param int $mode Constant
 814          *      - LIST_COMMA:          comma separated, no field names
 815          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
 816          *        the documentation for $conds in Database::select().
 817          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
 818          *      - LIST_SET:            comma separated with field names, like a SET clause
 819          *      - LIST_NAMES:          comma separated field names
 820          * @param array $binaryColumns Contains a list of column names that are binary types
 821          *      This is a custom parameter only present for MS SQL.
 822          *
 823          * @throws DBUnexpectedError
 824          * @return string
 825          */
 826         public function makeList( $a, $mode = LIST_COMMA, $binaryColumns = [] ) {
 827                 if ( !is_array( $a ) ) {
 828                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
 829                 }
 830
 831                 if ( $mode != LIST_NAMES ) {
 832                         // In MS SQL, values need to be specially encoded when they are
 833                         // inserted into binary fields. Perform this necessary encoding
 834                         // for the specified set of columns.
 835                         foreach ( array_keys( $a ) as $field ) {
 836                                 if ( !isset( $binaryColumns[$field] ) ) {
 837                                         continue;
 838                                 }
 839
 840                                 if ( is_array( $a[$field] ) ) {
 841                                         foreach ( $a[$field] as &$v ) {
 842                                                 $v = new MssqlBlob( $v );
 843                                         }
 844                                         unset( $v );
 845                                 } else {
 846                                         $a[$field] = new MssqlBlob( $a[$field] );
 847                                 }
 848                         }
 849                 }
 850
 851                 return parent::makeList( $a, $mode );
 852         }
 853
 854         /**
 855          * @param string $table
 856          * @param string $field
 857          * @return int Returns the size of a text field, or -1 for "unlimited"
 858          */
 859         public function textFieldSize( $table, $field ) {
 860                 $table = $this->tableName( $table );
 861                 $sql = "SELECT CHARACTER_MAXIMUM_LENGTH,DATA_TYPE FROM INFORMATION_SCHEMA.Columns
 862                         WHERE TABLE_NAME = '$table' AND COLUMN_NAME = '$field'";
 863                 $res = $this->query( $sql );
 864                 $row = $this->fetchRow( $res );
 865                 $size = -1;
 866                 if ( strtolower( $row['DATA_TYPE'] ) != 'text' ) {
 867                         $size = $row['CHARACTER_MAXIMUM_LENGTH'];
 868                 }
 869
 870                 return $size;
 871         }
 872
 873         /**
 874          * Construct a LIMIT query with optional offset
 875          * This is used for query pages
 876          *
 877          * @param string $sql SQL query we will append the limit too
 878          * @param int $limit The SQL limit
 879          * @param bool|int $offset The SQL offset (default false)
 880          * @return array|string
 881          * @throws DBUnexpectedError
 882          */
 883         public function limitResult( $sql, $limit, $offset = false ) {
 884                 if ( $offset === false || $offset == 0 ) {
 885                         if ( strpos( $sql, "SELECT" ) === false ) {
 886                                 return "TOP {$limit} " . $sql;
 887                         } else {
 888                                 return preg_replace( '/\bSELECT(\s+DISTINCT)?\b/Dsi',
 889                                         'SELECT$1 TOP ' . $limit, $sql, 1 );
 890                         }
 891                 } else {
 892                         // This one is fun, we need to pull out the select list as well as any ORDER BY clause
 893                         $select = $orderby = [];
 894                         $s1 = preg_match( '#SELECT\s+(.+?)\s+FROM#Dis', $sql, $select );
 895                         $s2 = preg_match( '#(ORDER BY\s+.+?)(\s*FOR XML .*)?$#Dis', $sql, $orderby );
 896                         $postOrder = '';
 897                         $first = $offset + 1;
 898                         $last = $offset + $limit;
 899                         $sub1 = 'sub_' . $this->subqueryId;
 900                         $sub2 = 'sub_' . ( $this->subqueryId + 1 );
 901                         $this->subqueryId += 2;
 902                         if ( !$s1 ) {
 903                                 // wat
 904                                 throw new DBUnexpectedError( $this, "Attempting to LIMIT a non-SELECT query\n" );
 905                         }
 906                         if ( !$s2 ) {
 907                                 // no ORDER BY
 908                                 $overOrder = 'ORDER BY (SELECT 1)';
 909                         } else {
 910                                 if ( !isset( $orderby[2] ) || !$orderby[2] ) {
 911                                         // don't need to strip it out if we're using a FOR XML clause
 912                                         $sql = str_replace( $orderby[1], '', $sql );
 913                                 }
 914                                 $overOrder = $orderby[1];
 915                                 $postOrder = ' ' . $overOrder;
 916                         }
 917                         $sql = "SELECT {$select[1]}
 918                                         FROM (
 919                                                 SELECT ROW_NUMBER() OVER({$overOrder}) AS rowNumber, *
 920                                                 FROM ({$sql}) {$sub1}
 921                                         ) {$sub2}
 922                                         WHERE rowNumber BETWEEN {$first} AND {$last}{$postOrder}";
 923
 924                         return $sql;
 925                 }
 926         }
 927
 928         /**
 929          * If there is a limit clause, parse it, strip it, and pass the remaining
 930          * SQL through limitResult() with the appropriate parameters. Not the
 931          * prettiest solution, but better than building a whole new parser. This
 932          * exists becase there are still too many extensions that don't use dynamic
 933          * sql generation.
 934          *
 935          * @param string $sql
 936          * @return array|mixed|string
 937          */
 938         public function LimitToTopN( $sql ) {
 939                 // Matches: LIMIT {[offset,] row_count | row_count OFFSET offset}
 940                 $pattern = '/\bLIMIT\s+((([0-9]+)\s*,\s*)?([0-9]+)(\s+OFFSET\s+([0-9]+))?)/i';
 941                 if ( preg_match( $pattern, $sql, $matches ) ) {
 942                         $row_count = $matches[4];
 943                         $offset = $matches[3] ?: $matches[6] ?: false;
 944
 945                         // strip the matching LIMIT clause out
 946                         $sql = str_replace( $matches[0], '', $sql );
 947
 948                         return $this->limitResult( $sql, $row_count, $offset );
 949                 }
 950
 951                 return $sql;
 952         }
 953
 954         /**
 955          * @return string Wikitext of a link to the server software's web site
 956          */
 957         public function getSoftwareLink() {
 958                 return "[{{int:version-db-mssql-url}} MS SQL Server]";
 959         }
 960
 961         /**
 962          * @return string Version information from the database
 963          */
 964         public function getServerVersion() {
 965                 $server_info = sqlsrv_server_info( $this->conn );
 966                 $version = 'Error';
 967                 if ( isset( $server_info['SQLServerVersion'] ) ) {
 968                         $version = $server_info['SQLServerVersion'];
 969                 }
 970
 971                 return $version;
 972         }
 973
 974         /**
 975          * @param string $table
 976          * @param string $fname
 977          * @return bool
 978          */
 979         public function tableExists( $table, $fname = __METHOD__ ) {
 980                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
 981
 982                 if ( $db !== false ) {
 983                         // remote database
 984                         $this->queryLogger->error( "Attempting to call tableExists on a remote table" );
 985                         return false;
 986                 }
 987
 988                 if ( $schema === false ) {
 989                         $schema = $this->schema;
 990                 }
 991
 992                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.TABLES
 993                         WHERE TABLE_TYPE = 'BASE TABLE'
 994                         AND TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table'" );
 995
 996                 if ( $res->numRows() ) {
 997                         return true;
 998                 } else {
 999                         return false;
1000                 }
1001         }
1002
1003         /**
1004          * Query whether a given column exists in the mediawiki schema
1005          * @param string $table
1006          * @param string $field
1007          * @param string $fname
1008          * @return bool
1009          */
1010         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1011                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
1012
1013                 if ( $db !== false ) {
1014                         // remote database
1015                         $this->queryLogger->error( "Attempting to call fieldExists on a remote table" );
1016                         return false;
1017                 }
1018
1019                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS
1020                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1021
1022                 if ( $res->numRows() ) {
1023                         return true;
1024                 } else {
1025                         return false;
1026                 }
1027         }
1028
1029         public function fieldInfo( $table, $field ) {
1030                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
1031
1032                 if ( $db !== false ) {
1033                         // remote database
1034                         $this->queryLogger->error( "Attempting to call fieldInfo on a remote table" );
1035                         return false;
1036                 }
1037
1038                 $res = $this->query( "SELECT * FROM INFORMATION_SCHEMA.COLUMNS
1039                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1040
1041                 $meta = $res->fetchRow();
1042                 if ( $meta ) {
1043                         return new MssqlField( $meta );
1044                 }
1045
1046                 return false;
1047         }
1048
1049         /**
1050          * Begin a transaction, committing any previously open transaction
1051          * @param string $fname
1052          */
1053         protected function doBegin( $fname = __METHOD__ ) {
1054                 sqlsrv_begin_transaction( $this->conn );
1055                 $this->trxLevel = 1;
1056         }
1057
1058         /**
1059          * End a transaction
1060          * @param string $fname
1061          */
1062         protected function doCommit( $fname = __METHOD__ ) {
1063                 sqlsrv_commit( $this->conn );
1064                 $this->trxLevel = 0;
1065         }
1066
1067         /**
1068          * Rollback a transaction.
1069          * No-op on non-transactional databases.
1070          * @param string $fname
1071          */
1072         protected function doRollback( $fname = __METHOD__ ) {
1073                 sqlsrv_rollback( $this->conn );
1074                 $this->trxLevel = 0;
1075         }
1076
1077         /**
1078          * @param string $s
1079          * @return string
1080          */
1081         public function strencode( $s ) {
1082                 // Should not be called by us
1083                 return str_replace( "'", "''", $s );
1084         }
1085
1086         /**
1087          * @param string|int|null|bool|Blob $s
1088          * @return string|int
1089          */
1090         public function addQuotes( $s ) {
1091                 if ( $s instanceof MssqlBlob ) {
1092                         return $s->fetch();
1093                 } elseif ( $s instanceof Blob ) {
1094                         // this shouldn't really ever be called, but it's here if needed
1095                         // (and will quite possibly make the SQL error out)
1096                         $blob = new MssqlBlob( $s->fetch() );
1097                         return $blob->fetch();
1098                 } else {
1099                         if ( is_bool( $s ) ) {
1100                                 $s = $s ? 1 : 0;
1101                         }
1102                         return parent::addQuotes( $s );
1103                 }
1104         }
1105
1106         /**
1107          * @param string $s
1108          * @return string
1109          */
1110         public function addIdentifierQuotes( $s ) {
1111                 // http://msdn.microsoft.com/en-us/library/aa223962.aspx
1112                 return '[' . $s . ']';
1113         }
1114
1115         /**
1116          * @param string $name
1117          * @return bool
1118          */
1119         public function isQuotedIdentifier( $name ) {
1120                 return strlen( $name ) && $name[0] == '[' && substr( $name, -1, 1 ) == ']';
1121         }
1122
1123         /**
1124          * MS SQL supports more pattern operators than other databases (ex: [,],^)
1125          *
1126          * @param string $s
1127          * @param string $escapeChar
1128          * @return string
1129          */
1130         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
1131                 return str_replace( [ $escapeChar, '%', '_', '[', ']', '^' ],
1132                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_",
1133                                 "{$escapeChar}[", "{$escapeChar}]", "{$escapeChar}^" ],
1134                         $s );
1135         }
1136
1137         /**
1138          * @param string $db
1139          * @return bool
1140          */
1141         public function selectDB( $db ) {
1142                 try {
1143                         $this->dbName = $db;
1144                         $this->query( "USE $db" );
1145                         return true;
1146                 } catch ( Exception $e ) {
1147                         return false;
1148                 }
1149         }
1150
1151         /**
1152          * @param array $options An associative array of options to be turned into
1153          *   an SQL query, valid keys are listed in the function.
1154          * @return array
1155          */
1156         public function makeSelectOptions( $options ) {
1157                 $tailOpts = '';
1158                 $startOpts = '';
1159
1160                 $noKeyOptions = [];
1161                 foreach ( $options as $key => $option ) {
1162                         if ( is_numeric( $key ) ) {
1163                                 $noKeyOptions[$option] = true;
1164                         }
1165                 }
1166
1167                 $tailOpts .= $this->makeGroupByWithHaving( $options );
1168
1169                 $tailOpts .= $this->makeOrderBy( $options );
1170
1171                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1172                         $startOpts .= 'DISTINCT';
1173                 }
1174
1175                 if ( isset( $noKeyOptions['FOR XML'] ) ) {
1176                         // used in group concat field emulation
1177                         $tailOpts .= " FOR XML PATH('')";
1178                 }
1179
1180                 // we want this to be compatible with the output of parent::makeSelectOptions()
1181                 return [ $startOpts, '', $tailOpts, '', '' ];
1182         }
1183
1184         public function getType() {
1185                 return 'mssql';
1186         }
1187
1188         /**
1189          * @param array $stringList
1190          * @return string
1191          */
1192         public function buildConcat( $stringList ) {
1193                 return implode( ' + ', $stringList );
1194         }
1195
1196         /**
1197          * Build a GROUP_CONCAT or equivalent statement for a query.
1198          * MS SQL doesn't have GROUP_CONCAT so we emulate it with other stuff (and boy is it nasty)
1199          *
1200          * This is useful for combining a field for several rows into a single string.
1201          * NULL values will not appear in the output, duplicated values will appear,
1202          * and the resulting delimiter-separated values have no defined sort order.
1203          * Code using the results may need to use the PHP unique() or sort() methods.
1204          *
1205          * @param string $delim Glue to bind the results together
1206          * @param string|array $table Table name
1207          * @param string $field Field name
1208          * @param string|array $conds Conditions
1209          * @param string|array $join_conds Join conditions
1210          * @return string SQL text
1211          * @since 1.23
1212          */
1213         public function buildGroupConcatField( $delim, $table, $field, $conds = '',
1214                 $join_conds = []
1215         ) {
1216                 $gcsq = 'gcsq_' . $this->subqueryId;
1217                 $this->subqueryId++;
1218
1219                 $delimLen = strlen( $delim );
1220                 $fld = "{$field} + {$this->addQuotes( $delim )}";
1221                 $sql = "(SELECT LEFT({$field}, LEN({$field}) - {$delimLen}) FROM ("
1222                         . $this->selectSQLText( $table, $fld, $conds, null, [ 'FOR XML' ], $join_conds )
1223                         . ") {$gcsq} ({$field}))";
1224
1225                 return $sql;
1226         }
1227
1228         /**
1229          * Returns an associative array for fields that are of type varbinary, binary, or image
1230          * $table can be either a raw table name or passed through tableName() first
1231          * @param string $table
1232          * @return array
1233          */
1234         private function getBinaryColumns( $table ) {
1235                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1236                 $tableRaw = array_pop( $tableRawArr );
1237
1238                 if ( $this->binaryColumnCache === null ) {
1239                         $this->populateColumnCaches();
1240                 }
1241
1242                 return isset( $this->binaryColumnCache[$tableRaw] )
1243                         ? $this->binaryColumnCache[$tableRaw]
1244                         : [];
1245         }
1246
1247         /**
1248          * @param string $table
1249          * @return array
1250          */
1251         private function getBitColumns( $table ) {
1252                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1253                 $tableRaw = array_pop( $tableRawArr );
1254
1255                 if ( $this->bitColumnCache === null ) {
1256                         $this->populateColumnCaches();
1257                 }
1258
1259                 return isset( $this->bitColumnCache[$tableRaw] )
1260                         ? $this->bitColumnCache[$tableRaw]
1261                         : [];
1262         }
1263
1264         private function populateColumnCaches() {
1265                 $res = $this->select( 'INFORMATION_SCHEMA.COLUMNS', '*',
1266                         [
1267                                 'TABLE_CATALOG' => $this->dbName,
1268                                 'TABLE_SCHEMA' => $this->schema,
1269                                 'DATA_TYPE' => [ 'varbinary', 'binary', 'image', 'bit' ]
1270                         ] );
1271
1272                 $this->binaryColumnCache = [];
1273                 $this->bitColumnCache = [];
1274                 foreach ( $res as $row ) {
1275                         if ( $row->DATA_TYPE == 'bit' ) {
1276                                 $this->bitColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1277                         } else {
1278                                 $this->binaryColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1279                         }
1280                 }
1281         }
1282
1283         /**
1284          * @param string $name
1285          * @param string $format
1286          * @return string
1287          */
1288         function tableName( $name, $format = 'quoted' ) {
1289                 # Replace reserved words with better ones
1290                 switch ( $name ) {
1291                         case 'user':
1292                                 return $this->realTableName( 'mwuser', $format );
1293                         default:
1294                                 return $this->realTableName( $name, $format );
1295                 }
1296         }
1297
1298         /**
1299          * call this instead of tableName() in the updater when renaming tables
1300          * @param string $name
1301          * @param string $format One of quoted, raw, or split
1302          * @return string
1303          */
1304         function realTableName( $name, $format = 'quoted' ) {
1305                 $table = parent::tableName( $name, $format );
1306                 if ( $format == 'split' ) {
1307                         // Used internally, we want the schema split off from the table name and returned
1308                         // as a list with 3 elements (database, schema, table)
1309                         $table = explode( '.', $table );
1310                         while ( count( $table ) < 3 ) {
1311                                 array_unshift( $table, false );
1312                         }
1313                 }
1314                 return $table;
1315         }
1316
1317         /**
1318          * Delete a table
1319          * @param string $tableName
1320          * @param string $fName
1321          * @return bool|ResultWrapper
1322          * @since 1.18
1323          */
1324         public function dropTable( $tableName, $fName = __METHOD__ ) {
1325                 if ( !$this->tableExists( $tableName, $fName ) ) {
1326                         return false;
1327                 }
1328
1329                 // parent function incorrectly appends CASCADE, which we don't want
1330                 $sql = "DROP TABLE " . $this->tableName( $tableName );
1331
1332                 return $this->query( $sql, $fName );
1333         }
1334
1335         /**
1336          * Called in the installer and updater.
1337          * Probably doesn't need to be called anywhere else in the codebase.
1338          * @param bool|null $value
1339          * @return bool|null
1340          */
1341         public function prepareStatements( $value = null ) {
1342                 $old = $this->prepareStatements;
1343                 if ( $value !== null ) {
1344                         $this->prepareStatements = $value;
1345                 }
1346
1347                 return $old;
1348         }
1349
1350         /**
1351          * Called in the installer and updater.
1352          * Probably doesn't need to be called anywhere else in the codebase.
1353          * @param bool|null $value
1354          * @return bool|null
1355          */
1356         public function scrollableCursor( $value = null ) {
1357                 $old = $this->scrollableCursor;
1358                 if ( $value !== null ) {
1359                         $this->scrollableCursor = $value;
1360                 }
1361
1362                 return $old;
1363         }
1364 }
1365
1366 class_alias( DatabaseMssql::class, 'DatabaseMssql' );