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 MediaWiki;
  31 use Exception;
  32 use stdClass;
  33
  34 /**
  35  * @ingroup Database
  36  */
  37 class DatabaseMssql extends Database {
  38         protected $mPort;
  39         protected $mUseWindowsAuth = false;
  40
  41         protected $mInsertId = null;
  42         protected $mLastResult = null;
  43         protected $mAffectedRows = null;
  44         protected $mSubqueryId = 0;
  45         protected $mScrollableCursor = true;
  46         protected $mPrepareStatements = true;
  47         protected $mBinaryColumnCache = null;
  48         protected $mBitColumnCache = null;
  49         protected $mIgnoreDupKeyErrors = false;
  50         protected $mIgnoreErrors = [];
  51
  52         public function implicitGroupby() {
  53                 return false;
  54         }
  55
  56         public function implicitOrderby() {
  57                 return false;
  58         }
  59
  60         public function unionSupportsOrderAndLimit() {
  61                 return false;
  62         }
  63
  64         public function __construct( array $params ) {
  65                 $this->mPort = $params['port'];
  66                 $this->mUseWindowsAuth = $params['UseWindowsAuth'];
  67
  68                 parent::__construct( $params );
  69         }
  70
  71         /**
  72          * Usually aborts on failure
  73          * @param string $server
  74          * @param string $user
  75          * @param string $password
  76          * @param string $dbName
  77          * @throws DBConnectionError
  78          * @return bool|resource|null
  79          */
  80         public function open( $server, $user, $password, $dbName ) {
  81                 # Test for driver support, to avoid suppressed fatal error
  82                 if ( !function_exists( 'sqlsrv_connect' ) ) {
  83                         throw new DBConnectionError(
  84                                 $this,
  85                                 "Microsoft SQL Server Native (sqlsrv) functions missing.
  86                                 You can download the driver from: http://go.microsoft.com/fwlink/?LinkId=123470\n"
  87                         );
  88                 }
  89
  90                 # e.g. the class is being loaded
  91                 if ( !strlen( $user ) ) {
  92                         return null;
  93                 }
  94
  95                 $this->close();
  96                 $this->mServer = $server;
  97                 $this->mUser = $user;
  98                 $this->mPassword = $password;
  99                 $this->mDBname = $dbName;
 100
 101                 $connectionInfo = [];
 102
 103                 if ( $dbName ) {
 104                         $connectionInfo['Database'] = $dbName;
 105                 }
 106
 107                 // Decide which auth scenerio to use
 108                 // if we are using Windows auth, then don't add credentials to $connectionInfo
 109                 if ( !$this->mUseWindowsAuth ) {
 110                         $connectionInfo['UID'] = $user;
 111                         $connectionInfo['PWD'] = $password;
 112                 }
 113
 114                 MediaWiki\suppressWarnings();
 115                 $this->mConn = sqlsrv_connect( $server, $connectionInfo );
 116                 MediaWiki\restoreWarnings();
 117
 118                 if ( $this->mConn === false ) {
 119                         throw new DBConnectionError( $this, $this->lastError() );
 120                 }
 121
 122                 $this->mOpened = true;
 123
 124                 return $this->mConn;
 125         }
 126
 127         /**
 128          * Closes a database connection, if it is open
 129          * Returns success, true if already closed
 130          * @return bool
 131          */
 132         protected function closeConnection() {
 133                 return sqlsrv_close( $this->mConn );
 134         }
 135
 136         /**
 137          * @param bool|MssqlResultWrapper|resource $result
 138          * @return bool|MssqlResultWrapper
 139          */
 140         protected function resultObject( $result ) {
 141                 if ( !$result ) {
 142                         return false;
 143                 } elseif ( $result instanceof MssqlResultWrapper ) {
 144                         return $result;
 145                 } elseif ( $result === true ) {
 146                         // Successful write query
 147                         return $result;
 148                 } else {
 149                         return new MssqlResultWrapper( $this, $result );
 150                 }
 151         }
 152
 153         /**
 154          * @param string $sql
 155          * @return bool|MssqlResultWrapper|resource
 156          * @throws DBUnexpectedError
 157          */
 158         protected function doQuery( $sql ) {
 159                 // several extensions seem to think that all databases support limits
 160                 // via LIMIT N after the WHERE clause, but  MSSQL uses SELECT TOP N,
 161                 // so to catch any of those extensions we'll do a quick check for a
 162                 // LIMIT clause and pass $sql through $this->LimitToTopN() which parses
 163                 // the LIMIT clause and passes the result to $this->limitResult();
 164                 if ( preg_match( '/\bLIMIT\s*/i', $sql ) ) {
 165                         // massage LIMIT -> TopN
 166                         $sql = $this->LimitToTopN( $sql );
 167                 }
 168
 169                 // MSSQL doesn't have EXTRACT(epoch FROM XXX)
 170                 if ( preg_match( '#\bEXTRACT\s*?\(\s*?EPOCH\s+FROM\b#i', $sql, $matches ) ) {
 171                         // This is same as UNIX_TIMESTAMP, we need to calc # of seconds from 1970
 172                         $sql = str_replace( $matches[0], "DATEDIFF(s,CONVERT(datetime,'1/1/1970'),", $sql );
 173                 }
 174
 175                 // perform query
 176
 177                 // SQLSRV_CURSOR_STATIC is slower than SQLSRV_CURSOR_CLIENT_BUFFERED (one of the two is
 178                 // needed if we want to be able to seek around the result set), however CLIENT_BUFFERED
 179                 // has a bug in the sqlsrv driver where wchar_t types (such as nvarchar) that are empty
 180                 // strings make php throw a fatal error "Severe error translating Unicode"
 181                 if ( $this->mScrollableCursor ) {
 182                         $scrollArr = [ 'Scrollable' => SQLSRV_CURSOR_STATIC ];
 183                 } else {
 184                         $scrollArr = [];
 185                 }
 186
 187                 if ( $this->mPrepareStatements ) {
 188                         // we do prepare + execute so we can get its field metadata for later usage if desired
 189                         $stmt = sqlsrv_prepare( $this->mConn, $sql, [], $scrollArr );
 190                         $success = sqlsrv_execute( $stmt );
 191                 } else {
 192                         $stmt = sqlsrv_query( $this->mConn, $sql, [], $scrollArr );
 193                         $success = (bool)$stmt;
 194                 }
 195
 196                 // Make a copy to ensure what we add below does not get reflected in future queries
 197                 $ignoreErrors = $this->mIgnoreErrors;
 198
 199                 if ( $this->mIgnoreDupKeyErrors ) {
 200                         // ignore duplicate key errors
 201                         // this emulates INSERT IGNORE in MySQL
 202                         $ignoreErrors[] = '2601'; // duplicate key error caused by unique index
 203                         $ignoreErrors[] = '2627'; // duplicate key error caused by primary key
 204                         $ignoreErrors[] = '3621'; // generic "the statement has been terminated" error
 205                 }
 206
 207                 if ( $success === false ) {
 208                         $errors = sqlsrv_errors();
 209                         $success = true;
 210
 211                         foreach ( $errors as $err ) {
 212                                 if ( !in_array( $err['code'], $ignoreErrors ) ) {
 213                                         $success = false;
 214                                         break;
 215                                 }
 216                         }
 217
 218                         if ( $success === false ) {
 219                                 return false;
 220                         }
 221                 }
 222                 // remember number of rows affected
 223                 $this->mAffectedRows = sqlsrv_rows_affected( $stmt );
 224
 225                 return $stmt;
 226         }
 227
 228         public function freeResult( $res ) {
 229                 if ( $res instanceof ResultWrapper ) {
 230                         $res = $res->result;
 231                 }
 232
 233                 sqlsrv_free_stmt( $res );
 234         }
 235
 236         /**
 237          * @param MssqlResultWrapper $res
 238          * @return stdClass
 239          */
 240         public function fetchObject( $res ) {
 241                 // $res is expected to be an instance of MssqlResultWrapper here
 242                 return $res->fetchObject();
 243         }
 244
 245         /**
 246          * @param MssqlResultWrapper $res
 247          * @return array
 248          */
 249         public function fetchRow( $res ) {
 250                 return $res->fetchRow();
 251         }
 252
 253         /**
 254          * @param mixed $res
 255          * @return int
 256          */
 257         public function numRows( $res ) {
 258                 if ( $res instanceof ResultWrapper ) {
 259                         $res = $res->result;
 260                 }
 261
 262                 $ret = sqlsrv_num_rows( $res );
 263
 264                 if ( $ret === false ) {
 265                         // we cannot get an amount of rows from this cursor type
 266                         // has_rows returns bool true/false if the result has rows
 267                         $ret = (int)sqlsrv_has_rows( $res );
 268                 }
 269
 270                 return $ret;
 271         }
 272
 273         /**
 274          * @param mixed $res
 275          * @return int
 276          */
 277         public function numFields( $res ) {
 278                 if ( $res instanceof ResultWrapper ) {
 279                         $res = $res->result;
 280                 }
 281
 282                 return sqlsrv_num_fields( $res );
 283         }
 284
 285         /**
 286          * @param mixed $res
 287          * @param int $n
 288          * @return int
 289          */
 290         public function fieldName( $res, $n ) {
 291                 if ( $res instanceof ResultWrapper ) {
 292                         $res = $res->result;
 293                 }
 294
 295                 return sqlsrv_field_metadata( $res )[$n]['Name'];
 296         }
 297
 298         /**
 299          * This must be called after nextSequenceVal
 300          * @return int|null
 301          */
 302         public function insertId() {
 303                 return $this->mInsertId;
 304         }
 305
 306         /**
 307          * @param MssqlResultWrapper $res
 308          * @param int $row
 309          * @return bool
 310          */
 311         public function dataSeek( $res, $row ) {
 312                 return $res->seek( $row );
 313         }
 314
 315         /**
 316          * @return string
 317          */
 318         public function lastError() {
 319                 $strRet = '';
 320                 $retErrors = sqlsrv_errors( SQLSRV_ERR_ALL );
 321                 if ( $retErrors != null ) {
 322                         foreach ( $retErrors as $arrError ) {
 323                                 $strRet .= $this->formatError( $arrError ) . "\n";
 324                         }
 325                 } else {
 326                         $strRet = "No errors found";
 327                 }
 328
 329                 return $strRet;
 330         }
 331
 332         /**
 333          * @param array $err
 334          * @return string
 335          */
 336         private function formatError( $err ) {
 337                 return '[SQLSTATE ' .
 338                         $err['SQLSTATE'] . '][Error Code ' . $err['code'] . ']' . $err['message'];
 339         }
 340
 341         /**
 342          * @return string|int
 343          */
 344         public function lastErrno() {
 345                 $err = sqlsrv_errors( SQLSRV_ERR_ALL );
 346                 if ( $err !== null && isset( $err[0] ) ) {
 347                         return $err[0]['code'];
 348                 } else {
 349                         return 0;
 350                 }
 351         }
 352
 353         /**
 354          * @return int
 355          */
 356         public function affectedRows() {
 357                 return $this->mAffectedRows;
 358         }
 359
 360         /**
 361          * SELECT wrapper
 362          *
 363          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 364          * @param mixed $vars Array or string, field name(s) to be retrieved
 365          * @param mixed $conds Array or string, condition(s) for WHERE
 366          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 367          * @param array $options Associative array of options (e.g.
 368          *   [ 'GROUP BY' => 'page_title' ]), see Database::makeSelectOptions
 369          *   code for list of supported stuff
 370          * @param array $join_conds Associative array of table join conditions
 371          *   (optional) (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 372          * @return mixed Database result resource (feed to Database::fetchObject
 373          *   or whatever), or false on failure
 374          * @throws DBQueryError
 375          * @throws DBUnexpectedError
 376          * @throws Exception
 377          */
 378         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
 379                 $options = [], $join_conds = []
 380         ) {
 381                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 382                 if ( isset( $options['EXPLAIN'] ) ) {
 383                         try {
 384                                 $this->mScrollableCursor = false;
 385                                 $this->mPrepareStatements = false;
 386                                 $this->query( "SET SHOWPLAN_ALL ON" );
 387                                 $ret = $this->query( $sql, $fname );
 388                                 $this->query( "SET SHOWPLAN_ALL OFF" );
 389                         } catch ( DBQueryError $dqe ) {
 390                                 if ( isset( $options['FOR COUNT'] ) ) {
 391                                         // likely don't have privs for SHOWPLAN, so run a select count instead
 392                                         $this->query( "SET SHOWPLAN_ALL OFF" );
 393                                         unset( $options['EXPLAIN'] );
 394                                         $ret = $this->select(
 395                                                 $table,
 396                                                 'COUNT(*) AS EstimateRows',
 397                                                 $conds,
 398                                                 $fname,
 399                                                 $options,
 400                                                 $join_conds
 401                                         );
 402                                 } else {
 403                                         // someone actually wanted the query plan instead of an est row count
 404                                         // let them know of the error
 405                                         $this->mScrollableCursor = true;
 406                                         $this->mPrepareStatements = true;
 407                                         throw $dqe;
 408                                 }
 409                         }
 410                         $this->mScrollableCursor = true;
 411                         $this->mPrepareStatements = true;
 412                         return $ret;
 413                 }
 414                 return $this->query( $sql, $fname );
 415         }
 416
 417         /**
 418          * SELECT wrapper
 419          *
 420          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 421          * @param mixed $vars Array or string, field name(s) to be retrieved
 422          * @param mixed $conds Array or string, condition(s) for WHERE
 423          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 424          * @param array $options Associative array of options (e.g. [ 'GROUP BY' => 'page_title' ]),
 425          *   see Database::makeSelectOptions code for list of supported stuff
 426          * @param array $join_conds Associative array of table join conditions (optional)
 427          *    (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 428          * @return string The SQL text
 429          */
 430         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
 431                 $options = [], $join_conds = []
 432         ) {
 433                 if ( isset( $options['EXPLAIN'] ) ) {
 434                         unset( $options['EXPLAIN'] );
 435                 }
 436
 437                 $sql = parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 438
 439                 // try to rewrite aggregations of bit columns (currently MAX and MIN)
 440                 if ( strpos( $sql, 'MAX(' ) !== false || strpos( $sql, 'MIN(' ) !== false ) {
 441                         $bitColumns = [];
 442                         if ( is_array( $table ) ) {
 443                                 foreach ( $table as $t ) {
 444                                         $bitColumns += $this->getBitColumns( $this->tableName( $t ) );
 445                                 }
 446                         } else {
 447                                 $bitColumns = $this->getBitColumns( $this->tableName( $table ) );
 448                         }
 449
 450                         foreach ( $bitColumns as $col => $info ) {
 451                                 $replace = [
 452                                         "MAX({$col})" => "MAX(CAST({$col} AS tinyint))",
 453                                         "MIN({$col})" => "MIN(CAST({$col} AS tinyint))",
 454                                 ];
 455                                 $sql = str_replace( array_keys( $replace ), array_values( $replace ), $sql );
 456                         }
 457                 }
 458
 459                 return $sql;
 460         }
 461
 462         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
 463                 $fname = __METHOD__
 464         ) {
 465                 $this->mScrollableCursor = false;
 466                 try {
 467                         parent::deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname );
 468                 } catch ( Exception $e ) {
 469                         $this->mScrollableCursor = true;
 470                         throw $e;
 471                 }
 472                 $this->mScrollableCursor = true;
 473         }
 474
 475         public function delete( $table, $conds, $fname = __METHOD__ ) {
 476                 $this->mScrollableCursor = false;
 477                 try {
 478                         parent::delete( $table, $conds, $fname );
 479                 } catch ( Exception $e ) {
 480                         $this->mScrollableCursor = true;
 481                         throw $e;
 482                 }
 483                 $this->mScrollableCursor = true;
 484         }
 485
 486         /**
 487          * Estimate rows in dataset
 488          * Returns estimated count, based on SHOWPLAN_ALL output
 489          * This is not necessarily an accurate estimate, so use sparingly
 490          * Returns -1 if count cannot be found
 491          * Takes same arguments as Database::select()
 492          * @param string $table
 493          * @param string $vars
 494          * @param string $conds
 495          * @param string $fname
 496          * @param array $options
 497          * @return int
 498          */
 499         public function estimateRowCount( $table, $vars = '*', $conds = '',
 500                 $fname = __METHOD__, $options = []
 501         ) {
 502                 // http://msdn2.microsoft.com/en-us/library/aa259203.aspx
 503                 $options['EXPLAIN'] = true;
 504                 $options['FOR COUNT'] = true;
 505                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 506
 507                 $rows = -1;
 508                 if ( $res ) {
 509                         $row = $this->fetchRow( $res );
 510
 511                         if ( isset( $row['EstimateRows'] ) ) {
 512                                 $rows = (int)$row['EstimateRows'];
 513                         }
 514                 }
 515
 516                 return $rows;
 517         }
 518
 519         /**
 520          * Returns information about an index
 521          * If errors are explicitly ignored, returns NULL on failure
 522          * @param string $table
 523          * @param string $index
 524          * @param string $fname
 525          * @return array|bool|null
 526          */
 527         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 528                 # This does not return the same info as MYSQL would, but that's OK
 529                 # because MediaWiki never uses the returned value except to check for
 530                 # the existence of indexes.
 531                 $sql = "sp_helpindex '" . $this->tableName( $table ) . "'";
 532                 $res = $this->query( $sql, $fname );
 533
 534                 if ( !$res ) {
 535                         return null;
 536                 }
 537
 538                 $result = [];
 539                 foreach ( $res as $row ) {
 540                         if ( $row->index_name == $index ) {
 541                                 $row->Non_unique = !stristr( $row->index_description, "unique" );
 542                                 $cols = explode( ", ", $row->index_keys );
 543                                 foreach ( $cols as $col ) {
 544                                         $row->Column_name = trim( $col );
 545                                         $result[] = clone $row;
 546                                 }
 547                         } elseif ( $index == 'PRIMARY' && stristr( $row->index_description, 'PRIMARY' ) ) {
 548                                 $row->Non_unique = 0;
 549                                 $cols = explode( ", ", $row->index_keys );
 550                                 foreach ( $cols as $col ) {
 551                                         $row->Column_name = trim( $col );
 552                                         $result[] = clone $row;
 553                                 }
 554                         }
 555                 }
 556
 557                 return empty( $result ) ? false : $result;
 558         }
 559
 560         /**
 561          * INSERT wrapper, inserts an array into a table
 562          *
 563          * $arrToInsert may be a single associative array, or an array of these with numeric keys, for
 564          * multi-row insert.
 565          *
 566          * Usually aborts on failure
 567          * If errors are explicitly ignored, returns success
 568          * @param string $table
 569          * @param array $arrToInsert
 570          * @param string $fname
 571          * @param array $options
 572          * @return bool
 573          * @throws Exception
 574          */
 575         public function insert( $table, $arrToInsert, $fname = __METHOD__, $options = [] ) {
 576                 # No rows to insert, easy just return now
 577                 if ( !count( $arrToInsert ) ) {
 578                         return true;
 579                 }
 580
 581                 if ( !is_array( $options ) ) {
 582                         $options = [ $options ];
 583                 }
 584
 585                 $table = $this->tableName( $table );
 586
 587                 if ( !( isset( $arrToInsert[0] ) && is_array( $arrToInsert[0] ) ) ) { // Not multi row
 588                         $arrToInsert = [ 0 => $arrToInsert ]; // make everything multi row compatible
 589                 }
 590
 591                 // We know the table we're inserting into, get its identity column
 592                 $identity = null;
 593                 // strip matching square brackets and the db/schema from table name
 594                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
 595                 $tableRaw = array_pop( $tableRawArr );
 596                 $res = $this->doQuery(
 597                         "SELECT NAME AS idColumn FROM SYS.IDENTITY_COLUMNS " .
 598                                 "WHERE OBJECT_NAME(OBJECT_ID)='{$tableRaw}'"
 599                 );
 600                 if ( $res && sqlsrv_has_rows( $res ) ) {
 601                         // There is an identity for this table.
 602                         $identityArr = sqlsrv_fetch_array( $res, SQLSRV_FETCH_ASSOC );
 603                         $identity = array_pop( $identityArr );
 604                 }
 605                 sqlsrv_free_stmt( $res );
 606
 607                 // Determine binary/varbinary fields so we can encode data as a hex string like 0xABCDEF
 608                 $binaryColumns = $this->getBinaryColumns( $table );
 609
 610                 // INSERT IGNORE is not supported by SQL Server
 611                 // remove IGNORE from options list and set ignore flag to true
 612                 if ( in_array( 'IGNORE', $options ) ) {
 613                         $options = array_diff( $options, [ 'IGNORE' ] );
 614                         $this->mIgnoreDupKeyErrors = true;
 615                 }
 616
 617                 $ret = null;
 618                 foreach ( $arrToInsert as $a ) {
 619                         // start out with empty identity column, this is so we can return
 620                         // it as a result of the INSERT logic
 621                         $sqlPre = '';
 622                         $sqlPost = '';
 623                         $identityClause = '';
 624
 625                         // if we have an identity column
 626                         if ( $identity ) {
 627                                 // iterate through
 628                                 foreach ( $a as $k => $v ) {
 629                                         if ( $k == $identity ) {
 630                                                 if ( !is_null( $v ) ) {
 631                                                         // there is a value being passed to us,
 632                                                         // we need to turn on and off inserted identity
 633                                                         $sqlPre = "SET IDENTITY_INSERT $table ON;";
 634                                                         $sqlPost = ";SET IDENTITY_INSERT $table OFF;";
 635                                                 } else {
 636                                                         // we can't insert NULL into an identity column,
 637                                                         // so remove the column from the insert.
 638                                                         unset( $a[$k] );
 639                                                 }
 640                                         }
 641                                 }
 642
 643                                 // we want to output an identity column as result
 644                                 $identityClause = "OUTPUT INSERTED.$identity ";
 645                         }
 646
 647                         $keys = array_keys( $a );
 648
 649                         // Build the actual query
 650                         $sql = $sqlPre . 'INSERT ' . implode( ' ', $options ) .
 651                                 " INTO $table (" . implode( ',', $keys ) . ") $identityClause VALUES (";
 652
 653                         $first = true;
 654                         foreach ( $a as $key => $value ) {
 655                                 if ( isset( $binaryColumns[$key] ) ) {
 656                                         $value = new MssqlBlob( $value );
 657                                 }
 658                                 if ( $first ) {
 659                                         $first = false;
 660                                 } else {
 661                                         $sql .= ',';
 662                                 }
 663                                 if ( is_null( $value ) ) {
 664                                         $sql .= 'null';
 665                                 } elseif ( is_array( $value ) || is_object( $value ) ) {
 666                                         if ( is_object( $value ) && $value instanceof Blob ) {
 667                                                 $sql .= $this->addQuotes( $value );
 668                                         } else {
 669                                                 $sql .= $this->addQuotes( serialize( $value ) );
 670                                         }
 671                                 } else {
 672                                         $sql .= $this->addQuotes( $value );
 673                                 }
 674                         }
 675                         $sql .= ')' . $sqlPost;
 676
 677                         // Run the query
 678                         $this->mScrollableCursor = false;
 679                         try {
 680                                 $ret = $this->query( $sql );
 681                         } catch ( Exception $e ) {
 682                                 $this->mScrollableCursor = true;
 683                                 $this->mIgnoreDupKeyErrors = false;
 684                                 throw $e;
 685                         }
 686                         $this->mScrollableCursor = true;
 687
 688                         if ( $ret instanceof ResultWrapper && !is_null( $identity ) ) {
 689                                 // Then we want to get the identity column value we were assigned and save it off
 690                                 $row = $ret->fetchObject();
 691                                 if ( is_object( $row ) ) {
 692                                         $this->mInsertId = $row->$identity;
 693                                         // It seems that mAffectedRows is -1 sometimes when OUTPUT INSERTED.identity is
 694                                         // used if we got an identity back, we know for sure a row was affected, so
 695                                         // adjust that here
 696                                         if ( $this->mAffectedRows == -1 ) {
 697                                                 $this->mAffectedRows = 1;
 698                                         }
 699                                 }
 700                         }
 701                 }
 702
 703                 $this->mIgnoreDupKeyErrors = false;
 704
 705                 return $ret;
 706         }
 707
 708         /**
 709          * INSERT SELECT wrapper
 710          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 711          * Source items may be literals rather than field names, but strings should
 712          * be quoted with Database::addQuotes().
 713          * @param string $destTable
 714          * @param array|string $srcTable May be an array of tables.
 715          * @param array $varMap
 716          * @param array $conds May be "*" to copy the whole table.
 717          * @param string $fname
 718          * @param array $insertOptions
 719          * @param array $selectOptions
 720          * @return null|ResultWrapper
 721          * @throws Exception
 722          */
 723         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 724                 $insertOptions = [], $selectOptions = []
 725         ) {
 726                 $this->mScrollableCursor = false;
 727                 try {
 728                         $ret = parent::nativeInsertSelect(
 729                                 $destTable,
 730                                 $srcTable,
 731                                 $varMap,
 732                                 $conds,
 733                                 $fname,
 734                                 $insertOptions,
 735                                 $selectOptions
 736                         );
 737                 } catch ( Exception $e ) {
 738                         $this->mScrollableCursor = true;
 739                         throw $e;
 740                 }
 741                 $this->mScrollableCursor = true;
 742
 743                 return $ret;
 744         }
 745
 746         /**
 747          * UPDATE wrapper. Takes a condition array and a SET array.
 748          *
 749          * @param string $table Name of the table to UPDATE. This will be passed through
 750          *                Database::tableName().
 751          *
 752          * @param array $values An array of values to SET. For each array element,
 753          *                the key gives the field name, and the value gives the data
 754          *                to set that field to. The data will be quoted by
 755          *                Database::addQuotes().
 756          *
 757          * @param array $conds An array of conditions (WHERE). See
 758          *                Database::select() for the details of the format of
 759          *                condition arrays. Use '*' to update all rows.
 760          *
 761          * @param string $fname The function name of the caller (from __METHOD__),
 762          *                for logging and profiling.
 763          *
 764          * @param array $options An array of UPDATE options, can be:
 765          *                   - IGNORE: Ignore unique key conflicts
 766          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
 767          * @return bool
 768          * @throws DBUnexpectedError
 769          * @throws Exception
 770          */
 771         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
 772                 $table = $this->tableName( $table );
 773                 $binaryColumns = $this->getBinaryColumns( $table );
 774
 775                 $opts = $this->makeUpdateOptions( $options );
 776                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET, $binaryColumns );
 777
 778                 if ( $conds !== [] && $conds !== '*' ) {
 779                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND, $binaryColumns );
 780                 }
 781
 782                 $this->mScrollableCursor = false;
 783                 try {
 784                         $this->query( $sql );
 785                 } catch ( Exception $e ) {
 786                         $this->mScrollableCursor = true;
 787                         throw $e;
 788                 }
 789                 $this->mScrollableCursor = true;
 790                 return true;
 791         }
 792
 793         /**
 794          * Makes an encoded list of strings from an array
 795          * @param array $a Containing the data
 796          * @param int $mode Constant
 797          *      - LIST_COMMA:          comma separated, no field names
 798          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
 799          *        the documentation for $conds in Database::select().
 800          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
 801          *      - LIST_SET:            comma separated with field names, like a SET clause
 802          *      - LIST_NAMES:          comma separated field names
 803          * @param array $binaryColumns Contains a list of column names that are binary types
 804          *      This is a custom parameter only present for MS SQL.
 805          *
 806          * @throws DBUnexpectedError
 807          * @return string
 808          */
 809         public function makeList( $a, $mode = LIST_COMMA, $binaryColumns = [] ) {
 810                 if ( !is_array( $a ) ) {
 811                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
 812                 }
 813
 814                 if ( $mode != LIST_NAMES ) {
 815                         // In MS SQL, values need to be specially encoded when they are
 816                         // inserted into binary fields. Perform this necessary encoding
 817                         // for the specified set of columns.
 818                         foreach ( array_keys( $a ) as $field ) {
 819                                 if ( !isset( $binaryColumns[$field] ) ) {
 820                                         continue;
 821                                 }
 822
 823                                 if ( is_array( $a[$field] ) ) {
 824                                         foreach ( $a[$field] as &$v ) {
 825                                                 $v = new MssqlBlob( $v );
 826                                         }
 827                                         unset( $v );
 828                                 } else {
 829                                         $a[$field] = new MssqlBlob( $a[$field] );
 830                                 }
 831                         }
 832                 }
 833
 834                 return parent::makeList( $a, $mode );
 835         }
 836
 837         /**
 838          * @param string $table
 839          * @param string $field
 840          * @return int Returns the size of a text field, or -1 for "unlimited"
 841          */
 842         public function textFieldSize( $table, $field ) {
 843                 $table = $this->tableName( $table );
 844                 $sql = "SELECT CHARACTER_MAXIMUM_LENGTH,DATA_TYPE FROM INFORMATION_SCHEMA.Columns
 845                         WHERE TABLE_NAME = '$table' AND COLUMN_NAME = '$field'";
 846                 $res = $this->query( $sql );
 847                 $row = $this->fetchRow( $res );
 848                 $size = -1;
 849                 if ( strtolower( $row['DATA_TYPE'] ) != 'text' ) {
 850                         $size = $row['CHARACTER_MAXIMUM_LENGTH'];
 851                 }
 852
 853                 return $size;
 854         }
 855
 856         /**
 857          * Construct a LIMIT query with optional offset
 858          * This is used for query pages
 859          *
 860          * @param string $sql SQL query we will append the limit too
 861          * @param int $limit The SQL limit
 862          * @param bool|int $offset The SQL offset (default false)
 863          * @return array|string
 864          * @throws DBUnexpectedError
 865          */
 866         public function limitResult( $sql, $limit, $offset = false ) {
 867                 if ( $offset === false || $offset == 0 ) {
 868                         if ( strpos( $sql, "SELECT" ) === false ) {
 869                                 return "TOP {$limit} " . $sql;
 870                         } else {
 871                                 return preg_replace( '/\bSELECT(\s+DISTINCT)?\b/Dsi',
 872                                         'SELECT$1 TOP ' . $limit, $sql, 1 );
 873                         }
 874                 } else {
 875                         // This one is fun, we need to pull out the select list as well as any ORDER BY clause
 876                         $select = $orderby = [];
 877                         $s1 = preg_match( '#SELECT\s+(.+?)\s+FROM#Dis', $sql, $select );
 878                         $s2 = preg_match( '#(ORDER BY\s+.+?)(\s*FOR XML .*)?$#Dis', $sql, $orderby );
 879                         $postOrder = '';
 880                         $first = $offset + 1;
 881                         $last = $offset + $limit;
 882                         $sub1 = 'sub_' . $this->mSubqueryId;
 883                         $sub2 = 'sub_' . ( $this->mSubqueryId + 1 );
 884                         $this->mSubqueryId += 2;
 885                         if ( !$s1 ) {
 886                                 // wat
 887                                 throw new DBUnexpectedError( $this, "Attempting to LIMIT a non-SELECT query\n" );
 888                         }
 889                         if ( !$s2 ) {
 890                                 // no ORDER BY
 891                                 $overOrder = 'ORDER BY (SELECT 1)';
 892                         } else {
 893                                 if ( !isset( $orderby[2] ) || !$orderby[2] ) {
 894                                         // don't need to strip it out if we're using a FOR XML clause
 895                                         $sql = str_replace( $orderby[1], '', $sql );
 896                                 }
 897                                 $overOrder = $orderby[1];
 898                                 $postOrder = ' ' . $overOrder;
 899                         }
 900                         $sql = "SELECT {$select[1]}
 901                                         FROM (
 902                                                 SELECT ROW_NUMBER() OVER({$overOrder}) AS rowNumber, *
 903                                                 FROM ({$sql}) {$sub1}
 904                                         ) {$sub2}
 905                                         WHERE rowNumber BETWEEN {$first} AND {$last}{$postOrder}";
 906
 907                         return $sql;
 908                 }
 909         }
 910
 911         /**
 912          * If there is a limit clause, parse it, strip it, and pass the remaining
 913          * SQL through limitResult() with the appropriate parameters. Not the
 914          * prettiest solution, but better than building a whole new parser. This
 915          * exists becase there are still too many extensions that don't use dynamic
 916          * sql generation.
 917          *
 918          * @param string $sql
 919          * @return array|mixed|string
 920          */
 921         public function LimitToTopN( $sql ) {
 922                 // Matches: LIMIT {[offset,] row_count | row_count OFFSET offset}
 923                 $pattern = '/\bLIMIT\s+((([0-9]+)\s*,\s*)?([0-9]+)(\s+OFFSET\s+([0-9]+))?)/i';
 924                 if ( preg_match( $pattern, $sql, $matches ) ) {
 925                         $row_count = $matches[4];
 926                         $offset = $matches[3] ?: $matches[6] ?: false;
 927
 928                         // strip the matching LIMIT clause out
 929                         $sql = str_replace( $matches[0], '', $sql );
 930
 931                         return $this->limitResult( $sql, $row_count, $offset );
 932                 }
 933
 934                 return $sql;
 935         }
 936
 937         /**
 938          * @return string Wikitext of a link to the server software's web site
 939          */
 940         public function getSoftwareLink() {
 941                 return "[{{int:version-db-mssql-url}} MS SQL Server]";
 942         }
 943
 944         /**
 945          * @return string Version information from the database
 946          */
 947         public function getServerVersion() {
 948                 $server_info = sqlsrv_server_info( $this->mConn );
 949                 $version = 'Error';
 950                 if ( isset( $server_info['SQLServerVersion'] ) ) {
 951                         $version = $server_info['SQLServerVersion'];
 952                 }
 953
 954                 return $version;
 955         }
 956
 957         /**
 958          * @param string $table
 959          * @param string $fname
 960          * @return bool
 961          */
 962         public function tableExists( $table, $fname = __METHOD__ ) {
 963                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
 964
 965                 if ( $db !== false ) {
 966                         // remote database
 967                         $this->queryLogger->error( "Attempting to call tableExists on a remote table" );
 968                         return false;
 969                 }
 970
 971                 if ( $schema === false ) {
 972                         $schema = $this->mSchema;
 973                 }
 974
 975                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.TABLES
 976                         WHERE TABLE_TYPE = 'BASE TABLE'
 977                         AND TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table'" );
 978
 979                 if ( $res->numRows() ) {
 980                         return true;
 981                 } else {
 982                         return false;
 983                 }
 984         }
 985
 986         /**
 987          * Query whether a given column exists in the mediawiki schema
 988          * @param string $table
 989          * @param string $field
 990          * @param string $fname
 991          * @return bool
 992          */
 993         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
 994                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
 995
 996                 if ( $db !== false ) {
 997                         // remote database
 998                         $this->queryLogger->error( "Attempting to call fieldExists on a remote table" );
 999                         return false;
1000                 }
1001
1002                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS
1003                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1004
1005                 if ( $res->numRows() ) {
1006                         return true;
1007                 } else {
1008                         return false;
1009                 }
1010         }
1011
1012         public function fieldInfo( $table, $field ) {
1013                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
1014
1015                 if ( $db !== false ) {
1016                         // remote database
1017                         $this->queryLogger->error( "Attempting to call fieldInfo on a remote table" );
1018                         return false;
1019                 }
1020
1021                 $res = $this->query( "SELECT * FROM INFORMATION_SCHEMA.COLUMNS
1022                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1023
1024                 $meta = $res->fetchRow();
1025                 if ( $meta ) {
1026                         return new MssqlField( $meta );
1027                 }
1028
1029                 return false;
1030         }
1031
1032         /**
1033          * Begin a transaction, committing any previously open transaction
1034          * @param string $fname
1035          */
1036         protected function doBegin( $fname = __METHOD__ ) {
1037                 sqlsrv_begin_transaction( $this->mConn );
1038                 $this->mTrxLevel = 1;
1039         }
1040
1041         /**
1042          * End a transaction
1043          * @param string $fname
1044          */
1045         protected function doCommit( $fname = __METHOD__ ) {
1046                 sqlsrv_commit( $this->mConn );
1047                 $this->mTrxLevel = 0;
1048         }
1049
1050         /**
1051          * Rollback a transaction.
1052          * No-op on non-transactional databases.
1053          * @param string $fname
1054          */
1055         protected function doRollback( $fname = __METHOD__ ) {
1056                 sqlsrv_rollback( $this->mConn );
1057                 $this->mTrxLevel = 0;
1058         }
1059
1060         /**
1061          * @param string $s
1062          * @return string
1063          */
1064         public function strencode( $s ) {
1065                 // Should not be called by us
1066
1067                 return str_replace( "'", "''", $s );
1068         }
1069
1070         /**
1071          * @param string|int|null|bool|Blob $s
1072          * @return string|int
1073          */
1074         public function addQuotes( $s ) {
1075                 if ( $s instanceof MssqlBlob ) {
1076                         return $s->fetch();
1077                 } elseif ( $s instanceof Blob ) {
1078                         // this shouldn't really ever be called, but it's here if needed
1079                         // (and will quite possibly make the SQL error out)
1080                         $blob = new MssqlBlob( $s->fetch() );
1081                         return $blob->fetch();
1082                 } else {
1083                         if ( is_bool( $s ) ) {
1084                                 $s = $s ? 1 : 0;
1085                         }
1086                         return parent::addQuotes( $s );
1087                 }
1088         }
1089
1090         /**
1091          * @param string $s
1092          * @return string
1093          */
1094         public function addIdentifierQuotes( $s ) {
1095                 // http://msdn.microsoft.com/en-us/library/aa223962.aspx
1096                 return '[' . $s . ']';
1097         }
1098
1099         /**
1100          * @param string $name
1101          * @return bool
1102          */
1103         public function isQuotedIdentifier( $name ) {
1104                 return strlen( $name ) && $name[0] == '[' && substr( $name, -1, 1 ) == ']';
1105         }
1106
1107         /**
1108          * MS SQL supports more pattern operators than other databases (ex: [,],^)
1109          *
1110          * @param string $s
1111          * @return string
1112          */
1113         protected function escapeLikeInternal( $s ) {
1114                 return addcslashes( $s, '\%_[]^' );
1115         }
1116
1117         /**
1118          * MS SQL requires specifying the escape character used in a LIKE query
1119          * or using Square brackets to surround characters that are to be escaped
1120          * https://msdn.microsoft.com/en-us/library/ms179859.aspx
1121          * Here we take the Specify-Escape-Character approach since it's less
1122          * invasive, renders a query that is closer to other DB's and better at
1123          * handling square bracket escaping
1124          *
1125          * @return string Fully built LIKE statement
1126          */
1127         public function buildLike() {
1128                 $params = func_get_args();
1129                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1130                         $params = $params[0];
1131                 }
1132
1133                 return parent::buildLike( $params ) . " ESCAPE '\' ";
1134         }
1135
1136         /**
1137          * @param string $db
1138          * @return bool
1139          */
1140         public function selectDB( $db ) {
1141                 try {
1142                         $this->mDBname = $db;
1143                         $this->query( "USE $db" );
1144                         return true;
1145                 } catch ( Exception $e ) {
1146                         return false;
1147                 }
1148         }
1149
1150         /**
1151          * @param array $options An associative array of options to be turned into
1152          *   an SQL query, valid keys are listed in the function.
1153          * @return array
1154          */
1155         public function makeSelectOptions( $options ) {
1156                 $tailOpts = '';
1157                 $startOpts = '';
1158
1159                 $noKeyOptions = [];
1160                 foreach ( $options as $key => $option ) {
1161                         if ( is_numeric( $key ) ) {
1162                                 $noKeyOptions[$option] = true;
1163                         }
1164                 }
1165
1166                 $tailOpts .= $this->makeGroupByWithHaving( $options );
1167
1168                 $tailOpts .= $this->makeOrderBy( $options );
1169
1170                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1171                         $startOpts .= 'DISTINCT';
1172                 }
1173
1174                 if ( isset( $noKeyOptions['FOR XML'] ) ) {
1175                         // used in group concat field emulation
1176                         $tailOpts .= " FOR XML PATH('')";
1177                 }
1178
1179                 // we want this to be compatible with the output of parent::makeSelectOptions()
1180                 return [ $startOpts, '', $tailOpts, '', '' ];
1181         }
1182
1183         public function getType() {
1184                 return 'mssql';
1185         }
1186
1187         /**
1188          * @param array $stringList
1189          * @return string
1190          */
1191         public function buildConcat( $stringList ) {
1192                 return implode( ' + ', $stringList );
1193         }
1194
1195         /**
1196          * Build a GROUP_CONCAT or equivalent statement for a query.
1197          * MS SQL doesn't have GROUP_CONCAT so we emulate it with other stuff (and boy is it nasty)
1198          *
1199          * This is useful for combining a field for several rows into a single string.
1200          * NULL values will not appear in the output, duplicated values will appear,
1201          * and the resulting delimiter-separated values have no defined sort order.
1202          * Code using the results may need to use the PHP unique() or sort() methods.
1203          *
1204          * @param string $delim Glue to bind the results together
1205          * @param string|array $table Table name
1206          * @param string $field Field name
1207          * @param string|array $conds Conditions
1208          * @param string|array $join_conds Join conditions
1209          * @return string SQL text
1210          * @since 1.23
1211          */
1212         public function buildGroupConcatField( $delim, $table, $field, $conds = '',
1213                 $join_conds = []
1214         ) {
1215                 $gcsq = 'gcsq_' . $this->mSubqueryId;
1216                 $this->mSubqueryId++;
1217
1218                 $delimLen = strlen( $delim );
1219                 $fld = "{$field} + {$this->addQuotes( $delim )}";
1220                 $sql = "(SELECT LEFT({$field}, LEN({$field}) - {$delimLen}) FROM ("
1221                         . $this->selectSQLText( $table, $fld, $conds, null, [ 'FOR XML' ], $join_conds )
1222                         . ") {$gcsq} ({$field}))";
1223
1224                 return $sql;
1225         }
1226
1227         /**
1228          * Returns an associative array for fields that are of type varbinary, binary, or image
1229          * $table can be either a raw table name or passed through tableName() first
1230          * @param string $table
1231          * @return array
1232          */
1233         private function getBinaryColumns( $table ) {
1234                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1235                 $tableRaw = array_pop( $tableRawArr );
1236
1237                 if ( $this->mBinaryColumnCache === null ) {
1238                         $this->populateColumnCaches();
1239                 }
1240
1241                 return isset( $this->mBinaryColumnCache[$tableRaw] )
1242                         ? $this->mBinaryColumnCache[$tableRaw]
1243                         : [];
1244         }
1245
1246         /**
1247          * @param string $table
1248          * @return array
1249          */
1250         private function getBitColumns( $table ) {
1251                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1252                 $tableRaw = array_pop( $tableRawArr );
1253
1254                 if ( $this->mBitColumnCache === null ) {
1255                         $this->populateColumnCaches();
1256                 }
1257
1258                 return isset( $this->mBitColumnCache[$tableRaw] )
1259                         ? $this->mBitColumnCache[$tableRaw]
1260                         : [];
1261         }
1262
1263         private function populateColumnCaches() {
1264                 $res = $this->select( 'INFORMATION_SCHEMA.COLUMNS', '*',
1265                         [
1266                                 'TABLE_CATALOG' => $this->mDBname,
1267                                 'TABLE_SCHEMA' => $this->mSchema,
1268                                 'DATA_TYPE' => [ 'varbinary', 'binary', 'image', 'bit' ]
1269                         ] );
1270
1271                 $this->mBinaryColumnCache = [];
1272                 $this->mBitColumnCache = [];
1273                 foreach ( $res as $row ) {
1274                         if ( $row->DATA_TYPE == 'bit' ) {
1275                                 $this->mBitColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1276                         } else {
1277                                 $this->mBinaryColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1278                         }
1279                 }
1280         }
1281
1282         /**
1283          * @param string $name
1284          * @param string $format
1285          * @return string
1286          */
1287         function tableName( $name, $format = 'quoted' ) {
1288                 # Replace reserved words with better ones
1289                 switch ( $name ) {
1290                         case 'user':
1291                                 return $this->realTableName( 'mwuser', $format );
1292                         default:
1293                                 return $this->realTableName( $name, $format );
1294                 }
1295         }
1296
1297         /**
1298          * call this instead of tableName() in the updater when renaming tables
1299          * @param string $name
1300          * @param string $format One of quoted, raw, or split
1301          * @return string
1302          */
1303         function realTableName( $name, $format = 'quoted' ) {
1304                 $table = parent::tableName( $name, $format );
1305                 if ( $format == 'split' ) {
1306                         // Used internally, we want the schema split off from the table name and returned
1307                         // as a list with 3 elements (database, schema, table)
1308                         $table = explode( '.', $table );
1309                         while ( count( $table ) < 3 ) {
1310                                 array_unshift( $table, false );
1311                         }
1312                 }
1313                 return $table;
1314         }
1315
1316         /**
1317          * Delete a table
1318          * @param string $tableName
1319          * @param string $fName
1320          * @return bool|ResultWrapper
1321          * @since 1.18
1322          */
1323         public function dropTable( $tableName, $fName = __METHOD__ ) {
1324                 if ( !$this->tableExists( $tableName, $fName ) ) {
1325                         return false;
1326                 }
1327
1328                 // parent function incorrectly appends CASCADE, which we don't want
1329                 $sql = "DROP TABLE " . $this->tableName( $tableName );
1330
1331                 return $this->query( $sql, $fName );
1332         }
1333
1334         /**
1335          * Called in the installer and updater.
1336          * Probably doesn't need to be called anywhere else in the codebase.
1337          * @param bool|null $value
1338          * @return bool|null
1339          */
1340         public function prepareStatements( $value = null ) {
1341                 $old = $this->mPrepareStatements;
1342                 if ( $value !== null ) {
1343                         $this->mPrepareStatements = $value;
1344                 }
1345
1346                 return $old;
1347         }
1348
1349         /**
1350          * Called in the installer and updater.
1351          * Probably doesn't need to be called anywhere else in the codebase.
1352          * @param bool|null $value
1353          * @return bool|null
1354          */
1355         public function scrollableCursor( $value = null ) {
1356                 $old = $this->mScrollableCursor;
1357                 if ( $value !== null ) {
1358                         $this->mScrollableCursor = $value;
1359                 }
1360
1361                 return $old;
1362         }
1363 }
1364
1365 class_alias( DatabaseMssql::class, 'DatabaseMssql' );