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 use Wikimedia\Rdbms\Blob;
  28 use Wikimedia\Rdbms\MssqlBlob;
  29
  30 /**
  31  * @ingroup Database
  32  */
  33 class DatabaseMssql extends Database {
  34         protected $mPort;
  35         protected $mUseWindowsAuth = false;
  36
  37         protected $mInsertId = null;
  38         protected $mLastResult = null;
  39         protected $mAffectedRows = null;
  40         protected $mSubqueryId = 0;
  41         protected $mScrollableCursor = true;
  42         protected $mPrepareStatements = true;
  43         protected $mBinaryColumnCache = null;
  44         protected $mBitColumnCache = null;
  45         protected $mIgnoreDupKeyErrors = false;
  46         protected $mIgnoreErrors = [];
  47
  48         public function implicitGroupby() {
  49                 return false;
  50         }
  51
  52         public function implicitOrderby() {
  53                 return false;
  54         }
  55
  56         public function unionSupportsOrderAndLimit() {
  57                 return false;
  58         }
  59
  60         public function __construct( array $params ) {
  61                 $this->mPort = $params['port'];
  62                 $this->mUseWindowsAuth = $params['UseWindowsAuth'];
  63
  64                 parent::__construct( $params );
  65         }
  66
  67         /**
  68          * Usually aborts on failure
  69          * @param string $server
  70          * @param string $user
  71          * @param string $password
  72          * @param string $dbName
  73          * @throws DBConnectionError
  74          * @return bool|resource|null
  75          */
  76         public function open( $server, $user, $password, $dbName ) {
  77                 # Test for driver support, to avoid suppressed fatal error
  78                 if ( !function_exists( 'sqlsrv_connect' ) ) {
  79                         throw new DBConnectionError(
  80                                 $this,
  81                                 "Microsoft SQL Server Native (sqlsrv) functions missing.
  82                                 You can download the driver from: http://go.microsoft.com/fwlink/?LinkId=123470\n"
  83                         );
  84                 }
  85
  86                 # e.g. the class is being loaded
  87                 if ( !strlen( $user ) ) {
  88                         return null;
  89                 }
  90
  91                 $this->close();
  92                 $this->mServer = $server;
  93                 $this->mUser = $user;
  94                 $this->mPassword = $password;
  95                 $this->mDBname = $dbName;
  96
  97                 $connectionInfo = [];
  98
  99                 if ( $dbName ) {
 100                         $connectionInfo['Database'] = $dbName;
 101                 }
 102
 103                 // Decide which auth scenerio to use
 104                 // if we are using Windows auth, then don't add credentials to $connectionInfo
 105                 if ( !$this->mUseWindowsAuth ) {
 106                         $connectionInfo['UID'] = $user;
 107                         $connectionInfo['PWD'] = $password;
 108                 }
 109
 110                 MediaWiki\suppressWarnings();
 111                 $this->mConn = sqlsrv_connect( $server, $connectionInfo );
 112                 MediaWiki\restoreWarnings();
 113
 114                 if ( $this->mConn === false ) {
 115                         throw new DBConnectionError( $this, $this->lastError() );
 116                 }
 117
 118                 $this->mOpened = true;
 119
 120                 return $this->mConn;
 121         }
 122
 123         /**
 124          * Closes a database connection, if it is open
 125          * Returns success, true if already closed
 126          * @return bool
 127          */
 128         protected function closeConnection() {
 129                 return sqlsrv_close( $this->mConn );
 130         }
 131
 132         /**
 133          * @param bool|MssqlResultWrapper|resource $result
 134          * @return bool|MssqlResultWrapper
 135          */
 136         protected function resultObject( $result ) {
 137                 if ( !$result ) {
 138                         return false;
 139                 } elseif ( $result instanceof MssqlResultWrapper ) {
 140                         return $result;
 141                 } elseif ( $result === true ) {
 142                         // Successful write query
 143                         return $result;
 144                 } else {
 145                         return new MssqlResultWrapper( $this, $result );
 146                 }
 147         }
 148
 149         /**
 150          * @param string $sql
 151          * @return bool|MssqlResultWrapper|resource
 152          * @throws DBUnexpectedError
 153          */
 154         protected function doQuery( $sql ) {
 155                 // several extensions seem to think that all databases support limits
 156                 // via LIMIT N after the WHERE clause, but  MSSQL uses SELECT TOP N,
 157                 // so to catch any of those extensions we'll do a quick check for a
 158                 // LIMIT clause and pass $sql through $this->LimitToTopN() which parses
 159                 // the LIMIT clause and passes the result to $this->limitResult();
 160                 if ( preg_match( '/\bLIMIT\s*/i', $sql ) ) {
 161                         // massage LIMIT -> TopN
 162                         $sql = $this->LimitToTopN( $sql );
 163                 }
 164
 165                 // MSSQL doesn't have EXTRACT(epoch FROM XXX)
 166                 if ( preg_match( '#\bEXTRACT\s*?\(\s*?EPOCH\s+FROM\b#i', $sql, $matches ) ) {
 167                         // This is same as UNIX_TIMESTAMP, we need to calc # of seconds from 1970
 168                         $sql = str_replace( $matches[0], "DATEDIFF(s,CONVERT(datetime,'1/1/1970'),", $sql );
 169                 }
 170
 171                 // perform query
 172
 173                 // SQLSRV_CURSOR_STATIC is slower than SQLSRV_CURSOR_CLIENT_BUFFERED (one of the two is
 174                 // needed if we want to be able to seek around the result set), however CLIENT_BUFFERED
 175                 // has a bug in the sqlsrv driver where wchar_t types (such as nvarchar) that are empty
 176                 // strings make php throw a fatal error "Severe error translating Unicode"
 177                 if ( $this->mScrollableCursor ) {
 178                         $scrollArr = [ 'Scrollable' => SQLSRV_CURSOR_STATIC ];
 179                 } else {
 180                         $scrollArr = [];
 181                 }
 182
 183                 if ( $this->mPrepareStatements ) {
 184                         // we do prepare + execute so we can get its field metadata for later usage if desired
 185                         $stmt = sqlsrv_prepare( $this->mConn, $sql, [], $scrollArr );
 186                         $success = sqlsrv_execute( $stmt );
 187                 } else {
 188                         $stmt = sqlsrv_query( $this->mConn, $sql, [], $scrollArr );
 189                         $success = (bool)$stmt;
 190                 }
 191
 192                 // Make a copy to ensure what we add below does not get reflected in future queries
 193                 $ignoreErrors = $this->mIgnoreErrors;
 194
 195                 if ( $this->mIgnoreDupKeyErrors ) {
 196                         // ignore duplicate key errors
 197                         // this emulates INSERT IGNORE in MySQL
 198                         $ignoreErrors[] = '2601'; // duplicate key error caused by unique index
 199                         $ignoreErrors[] = '2627'; // duplicate key error caused by primary key
 200                         $ignoreErrors[] = '3621'; // generic "the statement has been terminated" error
 201                 }
 202
 203                 if ( $success === false ) {
 204                         $errors = sqlsrv_errors();
 205                         $success = true;
 206
 207                         foreach ( $errors as $err ) {
 208                                 if ( !in_array( $err['code'], $ignoreErrors ) ) {
 209                                         $success = false;
 210                                         break;
 211                                 }
 212                         }
 213
 214                         if ( $success === false ) {
 215                                 return false;
 216                         }
 217                 }
 218                 // remember number of rows affected
 219                 $this->mAffectedRows = sqlsrv_rows_affected( $stmt );
 220
 221                 return $stmt;
 222         }
 223
 224         public function freeResult( $res ) {
 225                 if ( $res instanceof ResultWrapper ) {
 226                         $res = $res->result;
 227                 }
 228
 229                 sqlsrv_free_stmt( $res );
 230         }
 231
 232         /**
 233          * @param MssqlResultWrapper $res
 234          * @return stdClass
 235          */
 236         public function fetchObject( $res ) {
 237                 // $res is expected to be an instance of MssqlResultWrapper here
 238                 return $res->fetchObject();
 239         }
 240
 241         /**
 242          * @param MssqlResultWrapper $res
 243          * @return array
 244          */
 245         public function fetchRow( $res ) {
 246                 return $res->fetchRow();
 247         }
 248
 249         /**
 250          * @param mixed $res
 251          * @return int
 252          */
 253         public function numRows( $res ) {
 254                 if ( $res instanceof ResultWrapper ) {
 255                         $res = $res->result;
 256                 }
 257
 258                 $ret = sqlsrv_num_rows( $res );
 259
 260                 if ( $ret === false ) {
 261                         // we cannot get an amount of rows from this cursor type
 262                         // has_rows returns bool true/false if the result has rows
 263                         $ret = (int)sqlsrv_has_rows( $res );
 264                 }
 265
 266                 return $ret;
 267         }
 268
 269         /**
 270          * @param mixed $res
 271          * @return int
 272          */
 273         public function numFields( $res ) {
 274                 if ( $res instanceof ResultWrapper ) {
 275                         $res = $res->result;
 276                 }
 277
 278                 return sqlsrv_num_fields( $res );
 279         }
 280
 281         /**
 282          * @param mixed $res
 283          * @param int $n
 284          * @return int
 285          */
 286         public function fieldName( $res, $n ) {
 287                 if ( $res instanceof ResultWrapper ) {
 288                         $res = $res->result;
 289                 }
 290
 291                 return sqlsrv_field_metadata( $res )[$n]['Name'];
 292         }
 293
 294         /**
 295          * This must be called after nextSequenceVal
 296          * @return int|null
 297          */
 298         public function insertId() {
 299                 return $this->mInsertId;
 300         }
 301
 302         /**
 303          * @param MssqlResultWrapper $res
 304          * @param int $row
 305          * @return bool
 306          */
 307         public function dataSeek( $res, $row ) {
 308                 return $res->seek( $row );
 309         }
 310
 311         /**
 312          * @return string
 313          */
 314         public function lastError() {
 315                 $strRet = '';
 316                 $retErrors = sqlsrv_errors( SQLSRV_ERR_ALL );
 317                 if ( $retErrors != null ) {
 318                         foreach ( $retErrors as $arrError ) {
 319                                 $strRet .= $this->formatError( $arrError ) . "\n";
 320                         }
 321                 } else {
 322                         $strRet = "No errors found";
 323                 }
 324
 325                 return $strRet;
 326         }
 327
 328         /**
 329          * @param array $err
 330          * @return string
 331          */
 332         private function formatError( $err ) {
 333                 return '[SQLSTATE ' .
 334                         $err['SQLSTATE'] . '][Error Code ' . $err['code'] . ']' . $err['message'];
 335         }
 336
 337         /**
 338          * @return string|int
 339          */
 340         public function lastErrno() {
 341                 $err = sqlsrv_errors( SQLSRV_ERR_ALL );
 342                 if ( $err !== null && isset( $err[0] ) ) {
 343                         return $err[0]['code'];
 344                 } else {
 345                         return 0;
 346                 }
 347         }
 348
 349         /**
 350          * @return int
 351          */
 352         public function affectedRows() {
 353                 return $this->mAffectedRows;
 354         }
 355
 356         /**
 357          * SELECT wrapper
 358          *
 359          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 360          * @param mixed $vars Array or string, field name(s) to be retrieved
 361          * @param mixed $conds Array or string, condition(s) for WHERE
 362          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 363          * @param array $options Associative array of options (e.g.
 364          *   [ 'GROUP BY' => 'page_title' ]), see Database::makeSelectOptions
 365          *   code for list of supported stuff
 366          * @param array $join_conds Associative array of table join conditions
 367          *   (optional) (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 368          * @return mixed Database result resource (feed to Database::fetchObject
 369          *   or whatever), or false on failure
 370          * @throws DBQueryError
 371          * @throws DBUnexpectedError
 372          * @throws Exception
 373          */
 374         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
 375                 $options = [], $join_conds = []
 376         ) {
 377                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 378                 if ( isset( $options['EXPLAIN'] ) ) {
 379                         try {
 380                                 $this->mScrollableCursor = false;
 381                                 $this->mPrepareStatements = false;
 382                                 $this->query( "SET SHOWPLAN_ALL ON" );
 383                                 $ret = $this->query( $sql, $fname );
 384                                 $this->query( "SET SHOWPLAN_ALL OFF" );
 385                         } catch ( DBQueryError $dqe ) {
 386                                 if ( isset( $options['FOR COUNT'] ) ) {
 387                                         // likely don't have privs for SHOWPLAN, so run a select count instead
 388                                         $this->query( "SET SHOWPLAN_ALL OFF" );
 389                                         unset( $options['EXPLAIN'] );
 390                                         $ret = $this->select(
 391                                                 $table,
 392                                                 'COUNT(*) AS EstimateRows',
 393                                                 $conds,
 394                                                 $fname,
 395                                                 $options,
 396                                                 $join_conds
 397                                         );
 398                                 } else {
 399                                         // someone actually wanted the query plan instead of an est row count
 400                                         // let them know of the error
 401                                         $this->mScrollableCursor = true;
 402                                         $this->mPrepareStatements = true;
 403                                         throw $dqe;
 404                                 }
 405                         }
 406                         $this->mScrollableCursor = true;
 407                         $this->mPrepareStatements = true;
 408                         return $ret;
 409                 }
 410                 return $this->query( $sql, $fname );
 411         }
 412
 413         /**
 414          * SELECT wrapper
 415          *
 416          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 417          * @param mixed $vars Array or string, field name(s) to be retrieved
 418          * @param mixed $conds Array or string, condition(s) for WHERE
 419          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 420          * @param array $options Associative array of options (e.g. [ 'GROUP BY' => 'page_title' ]),
 421          *   see Database::makeSelectOptions code for list of supported stuff
 422          * @param array $join_conds Associative array of table join conditions (optional)
 423          *    (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 424          * @return string The SQL text
 425          */
 426         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
 427                 $options = [], $join_conds = []
 428         ) {
 429                 if ( isset( $options['EXPLAIN'] ) ) {
 430                         unset( $options['EXPLAIN'] );
 431                 }
 432
 433                 $sql = parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 434
 435                 // try to rewrite aggregations of bit columns (currently MAX and MIN)
 436                 if ( strpos( $sql, 'MAX(' ) !== false || strpos( $sql, 'MIN(' ) !== false ) {
 437                         $bitColumns = [];
 438                         if ( is_array( $table ) ) {
 439                                 foreach ( $table as $t ) {
 440                                         $bitColumns += $this->getBitColumns( $this->tableName( $t ) );
 441                                 }
 442                         } else {
 443                                 $bitColumns = $this->getBitColumns( $this->tableName( $table ) );
 444                         }
 445
 446                         foreach ( $bitColumns as $col => $info ) {
 447                                 $replace = [
 448                                         "MAX({$col})" => "MAX(CAST({$col} AS tinyint))",
 449                                         "MIN({$col})" => "MIN(CAST({$col} AS tinyint))",
 450                                 ];
 451                                 $sql = str_replace( array_keys( $replace ), array_values( $replace ), $sql );
 452                         }
 453                 }
 454
 455                 return $sql;
 456         }
 457
 458         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
 459                 $fname = __METHOD__
 460         ) {
 461                 $this->mScrollableCursor = false;
 462                 try {
 463                         parent::deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname );
 464                 } catch ( Exception $e ) {
 465                         $this->mScrollableCursor = true;
 466                         throw $e;
 467                 }
 468                 $this->mScrollableCursor = true;
 469         }
 470
 471         public function delete( $table, $conds, $fname = __METHOD__ ) {
 472                 $this->mScrollableCursor = false;
 473                 try {
 474                         parent::delete( $table, $conds, $fname );
 475                 } catch ( Exception $e ) {
 476                         $this->mScrollableCursor = true;
 477                         throw $e;
 478                 }
 479                 $this->mScrollableCursor = true;
 480         }
 481
 482         /**
 483          * Estimate rows in dataset
 484          * Returns estimated count, based on SHOWPLAN_ALL output
 485          * This is not necessarily an accurate estimate, so use sparingly
 486          * Returns -1 if count cannot be found
 487          * Takes same arguments as Database::select()
 488          * @param string $table
 489          * @param string $vars
 490          * @param string $conds
 491          * @param string $fname
 492          * @param array $options
 493          * @return int
 494          */
 495         public function estimateRowCount( $table, $vars = '*', $conds = '',
 496                 $fname = __METHOD__, $options = []
 497         ) {
 498                 // http://msdn2.microsoft.com/en-us/library/aa259203.aspx
 499                 $options['EXPLAIN'] = true;
 500                 $options['FOR COUNT'] = true;
 501                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 502
 503                 $rows = -1;
 504                 if ( $res ) {
 505                         $row = $this->fetchRow( $res );
 506
 507                         if ( isset( $row['EstimateRows'] ) ) {
 508                                 $rows = (int)$row['EstimateRows'];
 509                         }
 510                 }
 511
 512                 return $rows;
 513         }
 514
 515         /**
 516          * Returns information about an index
 517          * If errors are explicitly ignored, returns NULL on failure
 518          * @param string $table
 519          * @param string $index
 520          * @param string $fname
 521          * @return array|bool|null
 522          */
 523         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 524                 # This does not return the same info as MYSQL would, but that's OK
 525                 # because MediaWiki never uses the returned value except to check for
 526                 # the existence of indexes.
 527                 $sql = "sp_helpindex '" . $this->tableName( $table ) . "'";
 528                 $res = $this->query( $sql, $fname );
 529
 530                 if ( !$res ) {
 531                         return null;
 532                 }
 533
 534                 $result = [];
 535                 foreach ( $res as $row ) {
 536                         if ( $row->index_name == $index ) {
 537                                 $row->Non_unique = !stristr( $row->index_description, "unique" );
 538                                 $cols = explode( ", ", $row->index_keys );
 539                                 foreach ( $cols as $col ) {
 540                                         $row->Column_name = trim( $col );
 541                                         $result[] = clone $row;
 542                                 }
 543                         } elseif ( $index == 'PRIMARY' && stristr( $row->index_description, 'PRIMARY' ) ) {
 544                                 $row->Non_unique = 0;
 545                                 $cols = explode( ", ", $row->index_keys );
 546                                 foreach ( $cols as $col ) {
 547                                         $row->Column_name = trim( $col );
 548                                         $result[] = clone $row;
 549                                 }
 550                         }
 551                 }
 552
 553                 return empty( $result ) ? false : $result;
 554         }
 555
 556         /**
 557          * INSERT wrapper, inserts an array into a table
 558          *
 559          * $arrToInsert may be a single associative array, or an array of these with numeric keys, for
 560          * multi-row insert.
 561          *
 562          * Usually aborts on failure
 563          * If errors are explicitly ignored, returns success
 564          * @param string $table
 565          * @param array $arrToInsert
 566          * @param string $fname
 567          * @param array $options
 568          * @return bool
 569          * @throws Exception
 570          */
 571         public function insert( $table, $arrToInsert, $fname = __METHOD__, $options = [] ) {
 572                 # No rows to insert, easy just return now
 573                 if ( !count( $arrToInsert ) ) {
 574                         return true;
 575                 }
 576
 577                 if ( !is_array( $options ) ) {
 578                         $options = [ $options ];
 579                 }
 580
 581                 $table = $this->tableName( $table );
 582
 583                 if ( !( isset( $arrToInsert[0] ) && is_array( $arrToInsert[0] ) ) ) { // Not multi row
 584                         $arrToInsert = [ 0 => $arrToInsert ]; // make everything multi row compatible
 585                 }
 586
 587                 // We know the table we're inserting into, get its identity column
 588                 $identity = null;
 589                 // strip matching square brackets and the db/schema from table name
 590                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
 591                 $tableRaw = array_pop( $tableRawArr );
 592                 $res = $this->doQuery(
 593                         "SELECT NAME AS idColumn FROM SYS.IDENTITY_COLUMNS " .
 594                                 "WHERE OBJECT_NAME(OBJECT_ID)='{$tableRaw}'"
 595                 );
 596                 if ( $res && sqlsrv_has_rows( $res ) ) {
 597                         // There is an identity for this table.
 598                         $identityArr = sqlsrv_fetch_array( $res, SQLSRV_FETCH_ASSOC );
 599                         $identity = array_pop( $identityArr );
 600                 }
 601                 sqlsrv_free_stmt( $res );
 602
 603                 // Determine binary/varbinary fields so we can encode data as a hex string like 0xABCDEF
 604                 $binaryColumns = $this->getBinaryColumns( $table );
 605
 606                 // INSERT IGNORE is not supported by SQL Server
 607                 // remove IGNORE from options list and set ignore flag to true
 608                 if ( in_array( 'IGNORE', $options ) ) {
 609                         $options = array_diff( $options, [ 'IGNORE' ] );
 610                         $this->mIgnoreDupKeyErrors = true;
 611                 }
 612
 613                 $ret = null;
 614                 foreach ( $arrToInsert as $a ) {
 615                         // start out with empty identity column, this is so we can return
 616                         // it as a result of the INSERT logic
 617                         $sqlPre = '';
 618                         $sqlPost = '';
 619                         $identityClause = '';
 620
 621                         // if we have an identity column
 622                         if ( $identity ) {
 623                                 // iterate through
 624                                 foreach ( $a as $k => $v ) {
 625                                         if ( $k == $identity ) {
 626                                                 if ( !is_null( $v ) ) {
 627                                                         // there is a value being passed to us,
 628                                                         // we need to turn on and off inserted identity
 629                                                         $sqlPre = "SET IDENTITY_INSERT $table ON;";
 630                                                         $sqlPost = ";SET IDENTITY_INSERT $table OFF;";
 631                                                 } else {
 632                                                         // we can't insert NULL into an identity column,
 633                                                         // so remove the column from the insert.
 634                                                         unset( $a[$k] );
 635                                                 }
 636                                         }
 637                                 }
 638
 639                                 // we want to output an identity column as result
 640                                 $identityClause = "OUTPUT INSERTED.$identity ";
 641                         }
 642
 643                         $keys = array_keys( $a );
 644
 645                         // Build the actual query
 646                         $sql = $sqlPre . 'INSERT ' . implode( ' ', $options ) .
 647                                 " INTO $table (" . implode( ',', $keys ) . ") $identityClause VALUES (";
 648
 649                         $first = true;
 650                         foreach ( $a as $key => $value ) {
 651                                 if ( isset( $binaryColumns[$key] ) ) {
 652                                         $value = new MssqlBlob( $value );
 653                                 }
 654                                 if ( $first ) {
 655                                         $first = false;
 656                                 } else {
 657                                         $sql .= ',';
 658                                 }
 659                                 if ( is_null( $value ) ) {
 660                                         $sql .= 'null';
 661                                 } elseif ( is_array( $value ) || is_object( $value ) ) {
 662                                         if ( is_object( $value ) && $value instanceof Blob ) {
 663                                                 $sql .= $this->addQuotes( $value );
 664                                         } else {
 665                                                 $sql .= $this->addQuotes( serialize( $value ) );
 666                                         }
 667                                 } else {
 668                                         $sql .= $this->addQuotes( $value );
 669                                 }
 670                         }
 671                         $sql .= ')' . $sqlPost;
 672
 673                         // Run the query
 674                         $this->mScrollableCursor = false;
 675                         try {
 676                                 $ret = $this->query( $sql );
 677                         } catch ( Exception $e ) {
 678                                 $this->mScrollableCursor = true;
 679                                 $this->mIgnoreDupKeyErrors = false;
 680                                 throw $e;
 681                         }
 682                         $this->mScrollableCursor = true;
 683
 684                         if ( $ret instanceof ResultWrapper && !is_null( $identity ) ) {
 685                                 // Then we want to get the identity column value we were assigned and save it off
 686                                 $row = $ret->fetchObject();
 687                                 if ( is_object( $row ) ) {
 688                                         $this->mInsertId = $row->$identity;
 689                                         // It seems that mAffectedRows is -1 sometimes when OUTPUT INSERTED.identity is
 690                                         // used if we got an identity back, we know for sure a row was affected, so
 691                                         // adjust that here
 692                                         if ( $this->mAffectedRows == -1 ) {
 693                                                 $this->mAffectedRows = 1;
 694                                         }
 695                                 }
 696                         }
 697                 }
 698
 699                 $this->mIgnoreDupKeyErrors = false;
 700
 701                 return $ret;
 702         }
 703
 704         /**
 705          * INSERT SELECT wrapper
 706          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 707          * Source items may be literals rather than field names, but strings should
 708          * be quoted with Database::addQuotes().
 709          * @param string $destTable
 710          * @param array|string $srcTable May be an array of tables.
 711          * @param array $varMap
 712          * @param array $conds May be "*" to copy the whole table.
 713          * @param string $fname
 714          * @param array $insertOptions
 715          * @param array $selectOptions
 716          * @return null|ResultWrapper
 717          * @throws Exception
 718          */
 719         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 720                 $insertOptions = [], $selectOptions = []
 721         ) {
 722                 $this->mScrollableCursor = false;
 723                 try {
 724                         $ret = parent::nativeInsertSelect(
 725                                 $destTable,
 726                                 $srcTable,
 727                                 $varMap,
 728                                 $conds,
 729                                 $fname,
 730                                 $insertOptions,
 731                                 $selectOptions
 732                         );
 733                 } catch ( Exception $e ) {
 734                         $this->mScrollableCursor = true;
 735                         throw $e;
 736                 }
 737                 $this->mScrollableCursor = true;
 738
 739                 return $ret;
 740         }
 741
 742         /**
 743          * UPDATE wrapper. Takes a condition array and a SET array.
 744          *
 745          * @param string $table Name of the table to UPDATE. This will be passed through
 746          *                Database::tableName().
 747          *
 748          * @param array $values An array of values to SET. For each array element,
 749          *                the key gives the field name, and the value gives the data
 750          *                to set that field to. The data will be quoted by
 751          *                Database::addQuotes().
 752          *
 753          * @param array $conds An array of conditions (WHERE). See
 754          *                Database::select() for the details of the format of
 755          *                condition arrays. Use '*' to update all rows.
 756          *
 757          * @param string $fname The function name of the caller (from __METHOD__),
 758          *                for logging and profiling.
 759          *
 760          * @param array $options An array of UPDATE options, can be:
 761          *                   - IGNORE: Ignore unique key conflicts
 762          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
 763          * @return bool
 764          * @throws DBUnexpectedError
 765          * @throws Exception
 766          */
 767         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
 768                 $table = $this->tableName( $table );
 769                 $binaryColumns = $this->getBinaryColumns( $table );
 770
 771                 $opts = $this->makeUpdateOptions( $options );
 772                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET, $binaryColumns );
 773
 774                 if ( $conds !== [] && $conds !== '*' ) {
 775                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND, $binaryColumns );
 776                 }
 777
 778                 $this->mScrollableCursor = false;
 779                 try {
 780                         $this->query( $sql );
 781                 } catch ( Exception $e ) {
 782                         $this->mScrollableCursor = true;
 783                         throw $e;
 784                 }
 785                 $this->mScrollableCursor = true;
 786                 return true;
 787         }
 788
 789         /**
 790          * Makes an encoded list of strings from an array
 791          * @param array $a Containing the data
 792          * @param int $mode Constant
 793          *      - LIST_COMMA:          comma separated, no field names
 794          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
 795          *        the documentation for $conds in Database::select().
 796          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
 797          *      - LIST_SET:            comma separated with field names, like a SET clause
 798          *      - LIST_NAMES:          comma separated field names
 799          * @param array $binaryColumns Contains a list of column names that are binary types
 800          *      This is a custom parameter only present for MS SQL.
 801          *
 802          * @throws DBUnexpectedError
 803          * @return string
 804          */
 805         public function makeList( $a, $mode = LIST_COMMA, $binaryColumns = [] ) {
 806                 if ( !is_array( $a ) ) {
 807                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
 808                 }
 809
 810                 if ( $mode != LIST_NAMES ) {
 811                         // In MS SQL, values need to be specially encoded when they are
 812                         // inserted into binary fields. Perform this necessary encoding
 813                         // for the specified set of columns.
 814                         foreach ( array_keys( $a ) as $field ) {
 815                                 if ( !isset( $binaryColumns[$field] ) ) {
 816                                         continue;
 817                                 }
 818
 819                                 if ( is_array( $a[$field] ) ) {
 820                                         foreach ( $a[$field] as &$v ) {
 821                                                 $v = new MssqlBlob( $v );
 822                                         }
 823                                         unset( $v );
 824                                 } else {
 825                                         $a[$field] = new MssqlBlob( $a[$field] );
 826                                 }
 827                         }
 828                 }
 829
 830                 return parent::makeList( $a, $mode );
 831         }
 832
 833         /**
 834          * @param string $table
 835          * @param string $field
 836          * @return int Returns the size of a text field, or -1 for "unlimited"
 837          */
 838         public function textFieldSize( $table, $field ) {
 839                 $table = $this->tableName( $table );
 840                 $sql = "SELECT CHARACTER_MAXIMUM_LENGTH,DATA_TYPE FROM INFORMATION_SCHEMA.Columns
 841                         WHERE TABLE_NAME = '$table' AND COLUMN_NAME = '$field'";
 842                 $res = $this->query( $sql );
 843                 $row = $this->fetchRow( $res );
 844                 $size = -1;
 845                 if ( strtolower( $row['DATA_TYPE'] ) != 'text' ) {
 846                         $size = $row['CHARACTER_MAXIMUM_LENGTH'];
 847                 }
 848
 849                 return $size;
 850         }
 851
 852         /**
 853          * Construct a LIMIT query with optional offset
 854          * This is used for query pages
 855          *
 856          * @param string $sql SQL query we will append the limit too
 857          * @param int $limit The SQL limit
 858          * @param bool|int $offset The SQL offset (default false)
 859          * @return array|string
 860          * @throws DBUnexpectedError
 861          */
 862         public function limitResult( $sql, $limit, $offset = false ) {
 863                 if ( $offset === false || $offset == 0 ) {
 864                         if ( strpos( $sql, "SELECT" ) === false ) {
 865                                 return "TOP {$limit} " . $sql;
 866                         } else {
 867                                 return preg_replace( '/\bSELECT(\s+DISTINCT)?\b/Dsi',
 868                                         'SELECT$1 TOP ' . $limit, $sql, 1 );
 869                         }
 870                 } else {
 871                         // This one is fun, we need to pull out the select list as well as any ORDER BY clause
 872                         $select = $orderby = [];
 873                         $s1 = preg_match( '#SELECT\s+(.+?)\s+FROM#Dis', $sql, $select );
 874                         $s2 = preg_match( '#(ORDER BY\s+.+?)(\s*FOR XML .*)?$#Dis', $sql, $orderby );
 875                         $postOrder = '';
 876                         $first = $offset + 1;
 877                         $last = $offset + $limit;
 878                         $sub1 = 'sub_' . $this->mSubqueryId;
 879                         $sub2 = 'sub_' . ( $this->mSubqueryId + 1 );
 880                         $this->mSubqueryId += 2;
 881                         if ( !$s1 ) {
 882                                 // wat
 883                                 throw new DBUnexpectedError( $this, "Attempting to LIMIT a non-SELECT query\n" );
 884                         }
 885                         if ( !$s2 ) {
 886                                 // no ORDER BY
 887                                 $overOrder = 'ORDER BY (SELECT 1)';
 888                         } else {
 889                                 if ( !isset( $orderby[2] ) || !$orderby[2] ) {
 890                                         // don't need to strip it out if we're using a FOR XML clause
 891                                         $sql = str_replace( $orderby[1], '', $sql );
 892                                 }
 893                                 $overOrder = $orderby[1];
 894                                 $postOrder = ' ' . $overOrder;
 895                         }
 896                         $sql = "SELECT {$select[1]}
 897                                         FROM (
 898                                                 SELECT ROW_NUMBER() OVER({$overOrder}) AS rowNumber, *
 899                                                 FROM ({$sql}) {$sub1}
 900                                         ) {$sub2}
 901                                         WHERE rowNumber BETWEEN {$first} AND {$last}{$postOrder}";
 902
 903                         return $sql;
 904                 }
 905         }
 906
 907         /**
 908          * If there is a limit clause, parse it, strip it, and pass the remaining
 909          * SQL through limitResult() with the appropriate parameters. Not the
 910          * prettiest solution, but better than building a whole new parser. This
 911          * exists becase there are still too many extensions that don't use dynamic
 912          * sql generation.
 913          *
 914          * @param string $sql
 915          * @return array|mixed|string
 916          */
 917         public function LimitToTopN( $sql ) {
 918                 // Matches: LIMIT {[offset,] row_count | row_count OFFSET offset}
 919                 $pattern = '/\bLIMIT\s+((([0-9]+)\s*,\s*)?([0-9]+)(\s+OFFSET\s+([0-9]+))?)/i';
 920                 if ( preg_match( $pattern, $sql, $matches ) ) {
 921                         $row_count = $matches[4];
 922                         $offset = $matches[3] ?: $matches[6] ?: false;
 923
 924                         // strip the matching LIMIT clause out
 925                         $sql = str_replace( $matches[0], '', $sql );
 926
 927                         return $this->limitResult( $sql, $row_count, $offset );
 928                 }
 929
 930                 return $sql;
 931         }
 932
 933         /**
 934          * @return string Wikitext of a link to the server software's web site
 935          */
 936         public function getSoftwareLink() {
 937                 return "[{{int:version-db-mssql-url}} MS SQL Server]";
 938         }
 939
 940         /**
 941          * @return string Version information from the database
 942          */
 943         public function getServerVersion() {
 944                 $server_info = sqlsrv_server_info( $this->mConn );
 945                 $version = 'Error';
 946                 if ( isset( $server_info['SQLServerVersion'] ) ) {
 947                         $version = $server_info['SQLServerVersion'];
 948                 }
 949
 950                 return $version;
 951         }
 952
 953         /**
 954          * @param string $table
 955          * @param string $fname
 956          * @return bool
 957          */
 958         public function tableExists( $table, $fname = __METHOD__ ) {
 959                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
 960
 961                 if ( $db !== false ) {
 962                         // remote database
 963                         $this->queryLogger->error( "Attempting to call tableExists on a remote table" );
 964                         return false;
 965                 }
 966
 967                 if ( $schema === false ) {
 968                         $schema = $this->mSchema;
 969                 }
 970
 971                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.TABLES
 972                         WHERE TABLE_TYPE = 'BASE TABLE'
 973                         AND TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table'" );
 974
 975                 if ( $res->numRows() ) {
 976                         return true;
 977                 } else {
 978                         return false;
 979                 }
 980         }
 981
 982         /**
 983          * Query whether a given column exists in the mediawiki schema
 984          * @param string $table
 985          * @param string $field
 986          * @param string $fname
 987          * @return bool
 988          */
 989         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
 990                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
 991
 992                 if ( $db !== false ) {
 993                         // remote database
 994                         $this->queryLogger->error( "Attempting to call fieldExists on a remote table" );
 995                         return false;
 996                 }
 997
 998                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS
 999                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1000
1001                 if ( $res->numRows() ) {
1002                         return true;
1003                 } else {
1004                         return false;
1005                 }
1006         }
1007
1008         public function fieldInfo( $table, $field ) {
1009                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
1010
1011                 if ( $db !== false ) {
1012                         // remote database
1013                         $this->queryLogger->error( "Attempting to call fieldInfo on a remote table" );
1014                         return false;
1015                 }
1016
1017                 $res = $this->query( "SELECT * FROM INFORMATION_SCHEMA.COLUMNS
1018                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1019
1020                 $meta = $res->fetchRow();
1021                 if ( $meta ) {
1022                         return new MssqlField( $meta );
1023                 }
1024
1025                 return false;
1026         }
1027
1028         /**
1029          * Begin a transaction, committing any previously open transaction
1030          * @param string $fname
1031          */
1032         protected function doBegin( $fname = __METHOD__ ) {
1033                 sqlsrv_begin_transaction( $this->mConn );
1034                 $this->mTrxLevel = 1;
1035         }
1036
1037         /**
1038          * End a transaction
1039          * @param string $fname
1040          */
1041         protected function doCommit( $fname = __METHOD__ ) {
1042                 sqlsrv_commit( $this->mConn );
1043                 $this->mTrxLevel = 0;
1044         }
1045
1046         /**
1047          * Rollback a transaction.
1048          * No-op on non-transactional databases.
1049          * @param string $fname
1050          */
1051         protected function doRollback( $fname = __METHOD__ ) {
1052                 sqlsrv_rollback( $this->mConn );
1053                 $this->mTrxLevel = 0;
1054         }
1055
1056         /**
1057          * @param string $s
1058          * @return string
1059          */
1060         public function strencode( $s ) {
1061                 // Should not be called by us
1062
1063                 return str_replace( "'", "''", $s );
1064         }
1065
1066         /**
1067          * @param string|int|null|bool|Blob $s
1068          * @return string|int
1069          */
1070         public function addQuotes( $s ) {
1071                 if ( $s instanceof MssqlBlob ) {
1072                         return $s->fetch();
1073                 } elseif ( $s instanceof Blob ) {
1074                         // this shouldn't really ever be called, but it's here if needed
1075                         // (and will quite possibly make the SQL error out)
1076                         $blob = new MssqlBlob( $s->fetch() );
1077                         return $blob->fetch();
1078                 } else {
1079                         if ( is_bool( $s ) ) {
1080                                 $s = $s ? 1 : 0;
1081                         }
1082                         return parent::addQuotes( $s );
1083                 }
1084         }
1085
1086         /**
1087          * @param string $s
1088          * @return string
1089          */
1090         public function addIdentifierQuotes( $s ) {
1091                 // http://msdn.microsoft.com/en-us/library/aa223962.aspx
1092                 return '[' . $s . ']';
1093         }
1094
1095         /**
1096          * @param string $name
1097          * @return bool
1098          */
1099         public function isQuotedIdentifier( $name ) {
1100                 return strlen( $name ) && $name[0] == '[' && substr( $name, -1, 1 ) == ']';
1101         }
1102
1103         /**
1104          * MS SQL supports more pattern operators than other databases (ex: [,],^)
1105          *
1106          * @param string $s
1107          * @return string
1108          */
1109         protected function escapeLikeInternal( $s ) {
1110                 return addcslashes( $s, '\%_[]^' );
1111         }
1112
1113         /**
1114          * MS SQL requires specifying the escape character used in a LIKE query
1115          * or using Square brackets to surround characters that are to be escaped
1116          * https://msdn.microsoft.com/en-us/library/ms179859.aspx
1117          * Here we take the Specify-Escape-Character approach since it's less
1118          * invasive, renders a query that is closer to other DB's and better at
1119          * handling square bracket escaping
1120          *
1121          * @return string Fully built LIKE statement
1122          */
1123         public function buildLike() {
1124                 $params = func_get_args();
1125                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1126                         $params = $params[0];
1127                 }
1128
1129                 return parent::buildLike( $params ) . " ESCAPE '\' ";
1130         }
1131
1132         /**
1133          * @param string $db
1134          * @return bool
1135          */
1136         public function selectDB( $db ) {
1137                 try {
1138                         $this->mDBname = $db;
1139                         $this->query( "USE $db" );
1140                         return true;
1141                 } catch ( Exception $e ) {
1142                         return false;
1143                 }
1144         }
1145
1146         /**
1147          * @param array $options An associative array of options to be turned into
1148          *   an SQL query, valid keys are listed in the function.
1149          * @return array
1150          */
1151         public function makeSelectOptions( $options ) {
1152                 $tailOpts = '';
1153                 $startOpts = '';
1154
1155                 $noKeyOptions = [];
1156                 foreach ( $options as $key => $option ) {
1157                         if ( is_numeric( $key ) ) {
1158                                 $noKeyOptions[$option] = true;
1159                         }
1160                 }
1161
1162                 $tailOpts .= $this->makeGroupByWithHaving( $options );
1163
1164                 $tailOpts .= $this->makeOrderBy( $options );
1165
1166                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1167                         $startOpts .= 'DISTINCT';
1168                 }
1169
1170                 if ( isset( $noKeyOptions['FOR XML'] ) ) {
1171                         // used in group concat field emulation
1172                         $tailOpts .= " FOR XML PATH('')";
1173                 }
1174
1175                 // we want this to be compatible with the output of parent::makeSelectOptions()
1176                 return [ $startOpts, '', $tailOpts, '', '' ];
1177         }
1178
1179         public function getType() {
1180                 return 'mssql';
1181         }
1182
1183         /**
1184          * @param array $stringList
1185          * @return string
1186          */
1187         public function buildConcat( $stringList ) {
1188                 return implode( ' + ', $stringList );
1189         }
1190
1191         /**
1192          * Build a GROUP_CONCAT or equivalent statement for a query.
1193          * MS SQL doesn't have GROUP_CONCAT so we emulate it with other stuff (and boy is it nasty)
1194          *
1195          * This is useful for combining a field for several rows into a single string.
1196          * NULL values will not appear in the output, duplicated values will appear,
1197          * and the resulting delimiter-separated values have no defined sort order.
1198          * Code using the results may need to use the PHP unique() or sort() methods.
1199          *
1200          * @param string $delim Glue to bind the results together
1201          * @param string|array $table Table name
1202          * @param string $field Field name
1203          * @param string|array $conds Conditions
1204          * @param string|array $join_conds Join conditions
1205          * @return string SQL text
1206          * @since 1.23
1207          */
1208         public function buildGroupConcatField( $delim, $table, $field, $conds = '',
1209                 $join_conds = []
1210         ) {
1211                 $gcsq = 'gcsq_' . $this->mSubqueryId;
1212                 $this->mSubqueryId++;
1213
1214                 $delimLen = strlen( $delim );
1215                 $fld = "{$field} + {$this->addQuotes( $delim )}";
1216                 $sql = "(SELECT LEFT({$field}, LEN({$field}) - {$delimLen}) FROM ("
1217                         . $this->selectSQLText( $table, $fld, $conds, null, [ 'FOR XML' ], $join_conds )
1218                         . ") {$gcsq} ({$field}))";
1219
1220                 return $sql;
1221         }
1222
1223         /**
1224          * Returns an associative array for fields that are of type varbinary, binary, or image
1225          * $table can be either a raw table name or passed through tableName() first
1226          * @param string $table
1227          * @return array
1228          */
1229         private function getBinaryColumns( $table ) {
1230                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1231                 $tableRaw = array_pop( $tableRawArr );
1232
1233                 if ( $this->mBinaryColumnCache === null ) {
1234                         $this->populateColumnCaches();
1235                 }
1236
1237                 return isset( $this->mBinaryColumnCache[$tableRaw] )
1238                         ? $this->mBinaryColumnCache[$tableRaw]
1239                         : [];
1240         }
1241
1242         /**
1243          * @param string $table
1244          * @return array
1245          */
1246         private function getBitColumns( $table ) {
1247                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1248                 $tableRaw = array_pop( $tableRawArr );
1249
1250                 if ( $this->mBitColumnCache === null ) {
1251                         $this->populateColumnCaches();
1252                 }
1253
1254                 return isset( $this->mBitColumnCache[$tableRaw] )
1255                         ? $this->mBitColumnCache[$tableRaw]
1256                         : [];
1257         }
1258
1259         private function populateColumnCaches() {
1260                 $res = $this->select( 'INFORMATION_SCHEMA.COLUMNS', '*',
1261                         [
1262                                 'TABLE_CATALOG' => $this->mDBname,
1263                                 'TABLE_SCHEMA' => $this->mSchema,
1264                                 'DATA_TYPE' => [ 'varbinary', 'binary', 'image', 'bit' ]
1265                         ] );
1266
1267                 $this->mBinaryColumnCache = [];
1268                 $this->mBitColumnCache = [];
1269                 foreach ( $res as $row ) {
1270                         if ( $row->DATA_TYPE == 'bit' ) {
1271                                 $this->mBitColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1272                         } else {
1273                                 $this->mBinaryColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1274                         }
1275                 }
1276         }
1277
1278         /**
1279          * @param string $name
1280          * @param string $format
1281          * @return string
1282          */
1283         function tableName( $name, $format = 'quoted' ) {
1284                 # Replace reserved words with better ones
1285                 switch ( $name ) {
1286                         case 'user':
1287                                 return $this->realTableName( 'mwuser', $format );
1288                         default:
1289                                 return $this->realTableName( $name, $format );
1290                 }
1291         }
1292
1293         /**
1294          * call this instead of tableName() in the updater when renaming tables
1295          * @param string $name
1296          * @param string $format One of quoted, raw, or split
1297          * @return string
1298          */
1299         function realTableName( $name, $format = 'quoted' ) {
1300                 $table = parent::tableName( $name, $format );
1301                 if ( $format == 'split' ) {
1302                         // Used internally, we want the schema split off from the table name and returned
1303                         // as a list with 3 elements (database, schema, table)
1304                         $table = explode( '.', $table );
1305                         while ( count( $table ) < 3 ) {
1306                                 array_unshift( $table, false );
1307                         }
1308                 }
1309                 return $table;
1310         }
1311
1312         /**
1313          * Delete a table
1314          * @param string $tableName
1315          * @param string $fName
1316          * @return bool|ResultWrapper
1317          * @since 1.18
1318          */
1319         public function dropTable( $tableName, $fName = __METHOD__ ) {
1320                 if ( !$this->tableExists( $tableName, $fName ) ) {
1321                         return false;
1322                 }
1323
1324                 // parent function incorrectly appends CASCADE, which we don't want
1325                 $sql = "DROP TABLE " . $this->tableName( $tableName );
1326
1327                 return $this->query( $sql, $fName );
1328         }
1329
1330         /**
1331          * Called in the installer and updater.
1332          * Probably doesn't need to be called anywhere else in the codebase.
1333          * @param bool|null $value
1334          * @return bool|null
1335          */
1336         public function prepareStatements( $value = null ) {
1337                 $old = $this->mPrepareStatements;
1338                 if ( $value !== null ) {
1339                         $this->mPrepareStatements = $value;
1340                 }
1341
1342                 return $old;
1343         }
1344
1345         /**
1346          * Called in the installer and updater.
1347          * Probably doesn't need to be called anywhere else in the codebase.
1348          * @param bool|null $value
1349          * @return bool|null
1350          */
1351         public function scrollableCursor( $value = null ) {
1352                 $old = $this->mScrollableCursor;
1353                 if ( $value !== null ) {
1354                         $this->mScrollableCursor = $value;
1355                 }
1356
1357                 return $old;
1358         }
1359 }