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 DBConnectionError;
  32 use DBUnexpectedError;
  33 use DBQueryError;
  34 use Exception;
  35 use stdClass;
  36
  37 /**
  38  * @ingroup Database
  39  */
  40 class DatabaseMssql extends Database {
  41         protected $mPort;
  42         protected $mUseWindowsAuth = false;
  43
  44         protected $mInsertId = null;
  45         protected $mLastResult = null;
  46         protected $mAffectedRows = null;
  47         protected $mSubqueryId = 0;
  48         protected $mScrollableCursor = true;
  49         protected $mPrepareStatements = true;
  50         protected $mBinaryColumnCache = null;
  51         protected $mBitColumnCache = null;
  52         protected $mIgnoreDupKeyErrors = false;
  53         protected $mIgnoreErrors = [];
  54
  55         public function implicitGroupby() {
  56                 return false;
  57         }
  58
  59         public function implicitOrderby() {
  60                 return false;
  61         }
  62
  63         public function unionSupportsOrderAndLimit() {
  64                 return false;
  65         }
  66
  67         public function __construct( array $params ) {
  68                 $this->mPort = $params['port'];
  69                 $this->mUseWindowsAuth = $params['UseWindowsAuth'];
  70
  71                 parent::__construct( $params );
  72         }
  73
  74         /**
  75          * Usually aborts on failure
  76          * @param string $server
  77          * @param string $user
  78          * @param string $password
  79          * @param string $dbName
  80          * @throws DBConnectionError
  81          * @return bool|resource|null
  82          */
  83         public function open( $server, $user, $password, $dbName ) {
  84                 # Test for driver support, to avoid suppressed fatal error
  85                 if ( !function_exists( 'sqlsrv_connect' ) ) {
  86                         throw new DBConnectionError(
  87                                 $this,
  88                                 "Microsoft SQL Server Native (sqlsrv) functions missing.
  89                                 You can download the driver from: http://go.microsoft.com/fwlink/?LinkId=123470\n"
  90                         );
  91                 }
  92
  93                 # e.g. the class is being loaded
  94                 if ( !strlen( $user ) ) {
  95                         return null;
  96                 }
  97
  98                 $this->close();
  99                 $this->mServer = $server;
 100                 $this->mUser = $user;
 101                 $this->mPassword = $password;
 102                 $this->mDBname = $dbName;
 103
 104                 $connectionInfo = [];
 105
 106                 if ( $dbName ) {
 107                         $connectionInfo['Database'] = $dbName;
 108                 }
 109
 110                 // Decide which auth scenerio to use
 111                 // if we are using Windows auth, then don't add credentials to $connectionInfo
 112                 if ( !$this->mUseWindowsAuth ) {
 113                         $connectionInfo['UID'] = $user;
 114                         $connectionInfo['PWD'] = $password;
 115                 }
 116
 117                 MediaWiki\suppressWarnings();
 118                 $this->mConn = sqlsrv_connect( $server, $connectionInfo );
 119                 MediaWiki\restoreWarnings();
 120
 121                 if ( $this->mConn === false ) {
 122                         throw new DBConnectionError( $this, $this->lastError() );
 123                 }
 124
 125                 $this->mOpened = true;
 126
 127                 return $this->mConn;
 128         }
 129
 130         /**
 131          * Closes a database connection, if it is open
 132          * Returns success, true if already closed
 133          * @return bool
 134          */
 135         protected function closeConnection() {
 136                 return sqlsrv_close( $this->mConn );
 137         }
 138
 139         /**
 140          * @param bool|MssqlResultWrapper|resource $result
 141          * @return bool|MssqlResultWrapper
 142          */
 143         protected function resultObject( $result ) {
 144                 if ( !$result ) {
 145                         return false;
 146                 } elseif ( $result instanceof MssqlResultWrapper ) {
 147                         return $result;
 148                 } elseif ( $result === true ) {
 149                         // Successful write query
 150                         return $result;
 151                 } else {
 152                         return new MssqlResultWrapper( $this, $result );
 153                 }
 154         }
 155
 156         /**
 157          * @param string $sql
 158          * @return bool|MssqlResultWrapper|resource
 159          * @throws DBUnexpectedError
 160          */
 161         protected function doQuery( $sql ) {
 162                 // several extensions seem to think that all databases support limits
 163                 // via LIMIT N after the WHERE clause, but  MSSQL uses SELECT TOP N,
 164                 // so to catch any of those extensions we'll do a quick check for a
 165                 // LIMIT clause and pass $sql through $this->LimitToTopN() which parses
 166                 // the LIMIT clause and passes the result to $this->limitResult();
 167                 if ( preg_match( '/\bLIMIT\s*/i', $sql ) ) {
 168                         // massage LIMIT -> TopN
 169                         $sql = $this->LimitToTopN( $sql );
 170                 }
 171
 172                 // MSSQL doesn't have EXTRACT(epoch FROM XXX)
 173                 if ( preg_match( '#\bEXTRACT\s*?\(\s*?EPOCH\s+FROM\b#i', $sql, $matches ) ) {
 174                         // This is same as UNIX_TIMESTAMP, we need to calc # of seconds from 1970
 175                         $sql = str_replace( $matches[0], "DATEDIFF(s,CONVERT(datetime,'1/1/1970'),", $sql );
 176                 }
 177
 178                 // perform query
 179
 180                 // SQLSRV_CURSOR_STATIC is slower than SQLSRV_CURSOR_CLIENT_BUFFERED (one of the two is
 181                 // needed if we want to be able to seek around the result set), however CLIENT_BUFFERED
 182                 // has a bug in the sqlsrv driver where wchar_t types (such as nvarchar) that are empty
 183                 // strings make php throw a fatal error "Severe error translating Unicode"
 184                 if ( $this->mScrollableCursor ) {
 185                         $scrollArr = [ 'Scrollable' => SQLSRV_CURSOR_STATIC ];
 186                 } else {
 187                         $scrollArr = [];
 188                 }
 189
 190                 if ( $this->mPrepareStatements ) {
 191                         // we do prepare + execute so we can get its field metadata for later usage if desired
 192                         $stmt = sqlsrv_prepare( $this->mConn, $sql, [], $scrollArr );
 193                         $success = sqlsrv_execute( $stmt );
 194                 } else {
 195                         $stmt = sqlsrv_query( $this->mConn, $sql, [], $scrollArr );
 196                         $success = (bool)$stmt;
 197                 }
 198
 199                 // Make a copy to ensure what we add below does not get reflected in future queries
 200                 $ignoreErrors = $this->mIgnoreErrors;
 201
 202                 if ( $this->mIgnoreDupKeyErrors ) {
 203                         // ignore duplicate key errors
 204                         // this emulates INSERT IGNORE in MySQL
 205                         $ignoreErrors[] = '2601'; // duplicate key error caused by unique index
 206                         $ignoreErrors[] = '2627'; // duplicate key error caused by primary key
 207                         $ignoreErrors[] = '3621'; // generic "the statement has been terminated" error
 208                 }
 209
 210                 if ( $success === false ) {
 211                         $errors = sqlsrv_errors();
 212                         $success = true;
 213
 214                         foreach ( $errors as $err ) {
 215                                 if ( !in_array( $err['code'], $ignoreErrors ) ) {
 216                                         $success = false;
 217                                         break;
 218                                 }
 219                         }
 220
 221                         if ( $success === false ) {
 222                                 return false;
 223                         }
 224                 }
 225                 // remember number of rows affected
 226                 $this->mAffectedRows = sqlsrv_rows_affected( $stmt );
 227
 228                 return $stmt;
 229         }
 230
 231         public function freeResult( $res ) {
 232                 if ( $res instanceof ResultWrapper ) {
 233                         $res = $res->result;
 234                 }
 235
 236                 sqlsrv_free_stmt( $res );
 237         }
 238
 239         /**
 240          * @param MssqlResultWrapper $res
 241          * @return stdClass
 242          */
 243         public function fetchObject( $res ) {
 244                 // $res is expected to be an instance of MssqlResultWrapper here
 245                 return $res->fetchObject();
 246         }
 247
 248         /**
 249          * @param MssqlResultWrapper $res
 250          * @return array
 251          */
 252         public function fetchRow( $res ) {
 253                 return $res->fetchRow();
 254         }
 255
 256         /**
 257          * @param mixed $res
 258          * @return int
 259          */
 260         public function numRows( $res ) {
 261                 if ( $res instanceof ResultWrapper ) {
 262                         $res = $res->result;
 263                 }
 264
 265                 $ret = sqlsrv_num_rows( $res );
 266
 267                 if ( $ret === false ) {
 268                         // we cannot get an amount of rows from this cursor type
 269                         // has_rows returns bool true/false if the result has rows
 270                         $ret = (int)sqlsrv_has_rows( $res );
 271                 }
 272
 273                 return $ret;
 274         }
 275
 276         /**
 277          * @param mixed $res
 278          * @return int
 279          */
 280         public function numFields( $res ) {
 281                 if ( $res instanceof ResultWrapper ) {
 282                         $res = $res->result;
 283                 }
 284
 285                 return sqlsrv_num_fields( $res );
 286         }
 287
 288         /**
 289          * @param mixed $res
 290          * @param int $n
 291          * @return int
 292          */
 293         public function fieldName( $res, $n ) {
 294                 if ( $res instanceof ResultWrapper ) {
 295                         $res = $res->result;
 296                 }
 297
 298                 return sqlsrv_field_metadata( $res )[$n]['Name'];
 299         }
 300
 301         /**
 302          * This must be called after nextSequenceVal
 303          * @return int|null
 304          */
 305         public function insertId() {
 306                 return $this->mInsertId;
 307         }
 308
 309         /**
 310          * @param MssqlResultWrapper $res
 311          * @param int $row
 312          * @return bool
 313          */
 314         public function dataSeek( $res, $row ) {
 315                 return $res->seek( $row );
 316         }
 317
 318         /**
 319          * @return string
 320          */
 321         public function lastError() {
 322                 $strRet = '';
 323                 $retErrors = sqlsrv_errors( SQLSRV_ERR_ALL );
 324                 if ( $retErrors != null ) {
 325                         foreach ( $retErrors as $arrError ) {
 326                                 $strRet .= $this->formatError( $arrError ) . "\n";
 327                         }
 328                 } else {
 329                         $strRet = "No errors found";
 330                 }
 331
 332                 return $strRet;
 333         }
 334
 335         /**
 336          * @param array $err
 337          * @return string
 338          */
 339         private function formatError( $err ) {
 340                 return '[SQLSTATE ' .
 341                         $err['SQLSTATE'] . '][Error Code ' . $err['code'] . ']' . $err['message'];
 342         }
 343
 344         /**
 345          * @return string|int
 346          */
 347         public function lastErrno() {
 348                 $err = sqlsrv_errors( SQLSRV_ERR_ALL );
 349                 if ( $err !== null && isset( $err[0] ) ) {
 350                         return $err[0]['code'];
 351                 } else {
 352                         return 0;
 353                 }
 354         }
 355
 356         /**
 357          * @return int
 358          */
 359         public function affectedRows() {
 360                 return $this->mAffectedRows;
 361         }
 362
 363         /**
 364          * SELECT wrapper
 365          *
 366          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 367          * @param mixed $vars Array or string, field name(s) to be retrieved
 368          * @param mixed $conds Array or string, condition(s) for WHERE
 369          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 370          * @param array $options Associative array of options (e.g.
 371          *   [ 'GROUP BY' => 'page_title' ]), see Database::makeSelectOptions
 372          *   code for list of supported stuff
 373          * @param array $join_conds Associative array of table join conditions
 374          *   (optional) (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 375          * @return mixed Database result resource (feed to Database::fetchObject
 376          *   or whatever), or false on failure
 377          * @throws DBQueryError
 378          * @throws DBUnexpectedError
 379          * @throws Exception
 380          */
 381         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
 382                 $options = [], $join_conds = []
 383         ) {
 384                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 385                 if ( isset( $options['EXPLAIN'] ) ) {
 386                         try {
 387                                 $this->mScrollableCursor = false;
 388                                 $this->mPrepareStatements = false;
 389                                 $this->query( "SET SHOWPLAN_ALL ON" );
 390                                 $ret = $this->query( $sql, $fname );
 391                                 $this->query( "SET SHOWPLAN_ALL OFF" );
 392                         } catch ( DBQueryError $dqe ) {
 393                                 if ( isset( $options['FOR COUNT'] ) ) {
 394                                         // likely don't have privs for SHOWPLAN, so run a select count instead
 395                                         $this->query( "SET SHOWPLAN_ALL OFF" );
 396                                         unset( $options['EXPLAIN'] );
 397                                         $ret = $this->select(
 398                                                 $table,
 399                                                 'COUNT(*) AS EstimateRows',
 400                                                 $conds,
 401                                                 $fname,
 402                                                 $options,
 403                                                 $join_conds
 404                                         );
 405                                 } else {
 406                                         // someone actually wanted the query plan instead of an est row count
 407                                         // let them know of the error
 408                                         $this->mScrollableCursor = true;
 409                                         $this->mPrepareStatements = true;
 410                                         throw $dqe;
 411                                 }
 412                         }
 413                         $this->mScrollableCursor = true;
 414                         $this->mPrepareStatements = true;
 415                         return $ret;
 416                 }
 417                 return $this->query( $sql, $fname );
 418         }
 419
 420         /**
 421          * SELECT wrapper
 422          *
 423          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 424          * @param mixed $vars Array or string, field name(s) to be retrieved
 425          * @param mixed $conds Array or string, condition(s) for WHERE
 426          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 427          * @param array $options Associative array of options (e.g. [ 'GROUP BY' => 'page_title' ]),
 428          *   see Database::makeSelectOptions code for list of supported stuff
 429          * @param array $join_conds Associative array of table join conditions (optional)
 430          *    (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 431          * @return string The SQL text
 432          */
 433         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
 434                 $options = [], $join_conds = []
 435         ) {
 436                 if ( isset( $options['EXPLAIN'] ) ) {
 437                         unset( $options['EXPLAIN'] );
 438                 }
 439
 440                 $sql = parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 441
 442                 // try to rewrite aggregations of bit columns (currently MAX and MIN)
 443                 if ( strpos( $sql, 'MAX(' ) !== false || strpos( $sql, 'MIN(' ) !== false ) {
 444                         $bitColumns = [];
 445                         if ( is_array( $table ) ) {
 446                                 foreach ( $table as $t ) {
 447                                         $bitColumns += $this->getBitColumns( $this->tableName( $t ) );
 448                                 }
 449                         } else {
 450                                 $bitColumns = $this->getBitColumns( $this->tableName( $table ) );
 451                         }
 452
 453                         foreach ( $bitColumns as $col => $info ) {
 454                                 $replace = [
 455                                         "MAX({$col})" => "MAX(CAST({$col} AS tinyint))",
 456                                         "MIN({$col})" => "MIN(CAST({$col} AS tinyint))",
 457                                 ];
 458                                 $sql = str_replace( array_keys( $replace ), array_values( $replace ), $sql );
 459                         }
 460                 }
 461
 462                 return $sql;
 463         }
 464
 465         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
 466                 $fname = __METHOD__
 467         ) {
 468                 $this->mScrollableCursor = false;
 469                 try {
 470                         parent::deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname );
 471                 } catch ( Exception $e ) {
 472                         $this->mScrollableCursor = true;
 473                         throw $e;
 474                 }
 475                 $this->mScrollableCursor = true;
 476         }
 477
 478         public function delete( $table, $conds, $fname = __METHOD__ ) {
 479                 $this->mScrollableCursor = false;
 480                 try {
 481                         parent::delete( $table, $conds, $fname );
 482                 } catch ( Exception $e ) {
 483                         $this->mScrollableCursor = true;
 484                         throw $e;
 485                 }
 486                 $this->mScrollableCursor = true;
 487         }
 488
 489         /**
 490          * Estimate rows in dataset
 491          * Returns estimated count, based on SHOWPLAN_ALL output
 492          * This is not necessarily an accurate estimate, so use sparingly
 493          * Returns -1 if count cannot be found
 494          * Takes same arguments as Database::select()
 495          * @param string $table
 496          * @param string $vars
 497          * @param string $conds
 498          * @param string $fname
 499          * @param array $options
 500          * @return int
 501          */
 502         public function estimateRowCount( $table, $vars = '*', $conds = '',
 503                 $fname = __METHOD__, $options = []
 504         ) {
 505                 // http://msdn2.microsoft.com/en-us/library/aa259203.aspx
 506                 $options['EXPLAIN'] = true;
 507                 $options['FOR COUNT'] = true;
 508                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 509
 510                 $rows = -1;
 511                 if ( $res ) {
 512                         $row = $this->fetchRow( $res );
 513
 514                         if ( isset( $row['EstimateRows'] ) ) {
 515                                 $rows = (int)$row['EstimateRows'];
 516                         }
 517                 }
 518
 519                 return $rows;
 520         }
 521
 522         /**
 523          * Returns information about an index
 524          * If errors are explicitly ignored, returns NULL on failure
 525          * @param string $table
 526          * @param string $index
 527          * @param string $fname
 528          * @return array|bool|null
 529          */
 530         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 531                 # This does not return the same info as MYSQL would, but that's OK
 532                 # because MediaWiki never uses the returned value except to check for
 533                 # the existence of indexes.
 534                 $sql = "sp_helpindex '" . $this->tableName( $table ) . "'";
 535                 $res = $this->query( $sql, $fname );
 536
 537                 if ( !$res ) {
 538                         return null;
 539                 }
 540
 541                 $result = [];
 542                 foreach ( $res as $row ) {
 543                         if ( $row->index_name == $index ) {
 544                                 $row->Non_unique = !stristr( $row->index_description, "unique" );
 545                                 $cols = explode( ", ", $row->index_keys );
 546                                 foreach ( $cols as $col ) {
 547                                         $row->Column_name = trim( $col );
 548                                         $result[] = clone $row;
 549                                 }
 550                         } elseif ( $index == 'PRIMARY' && stristr( $row->index_description, 'PRIMARY' ) ) {
 551                                 $row->Non_unique = 0;
 552                                 $cols = explode( ", ", $row->index_keys );
 553                                 foreach ( $cols as $col ) {
 554                                         $row->Column_name = trim( $col );
 555                                         $result[] = clone $row;
 556                                 }
 557                         }
 558                 }
 559
 560                 return empty( $result ) ? false : $result;
 561         }
 562
 563         /**
 564          * INSERT wrapper, inserts an array into a table
 565          *
 566          * $arrToInsert may be a single associative array, or an array of these with numeric keys, for
 567          * multi-row insert.
 568          *
 569          * Usually aborts on failure
 570          * If errors are explicitly ignored, returns success
 571          * @param string $table
 572          * @param array $arrToInsert
 573          * @param string $fname
 574          * @param array $options
 575          * @return bool
 576          * @throws Exception
 577          */
 578         public function insert( $table, $arrToInsert, $fname = __METHOD__, $options = [] ) {
 579                 # No rows to insert, easy just return now
 580                 if ( !count( $arrToInsert ) ) {
 581                         return true;
 582                 }
 583
 584                 if ( !is_array( $options ) ) {
 585                         $options = [ $options ];
 586                 }
 587
 588                 $table = $this->tableName( $table );
 589
 590                 if ( !( isset( $arrToInsert[0] ) && is_array( $arrToInsert[0] ) ) ) { // Not multi row
 591                         $arrToInsert = [ 0 => $arrToInsert ]; // make everything multi row compatible
 592                 }
 593
 594                 // We know the table we're inserting into, get its identity column
 595                 $identity = null;
 596                 // strip matching square brackets and the db/schema from table name
 597                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
 598                 $tableRaw = array_pop( $tableRawArr );
 599                 $res = $this->doQuery(
 600                         "SELECT NAME AS idColumn FROM SYS.IDENTITY_COLUMNS " .
 601                                 "WHERE OBJECT_NAME(OBJECT_ID)='{$tableRaw}'"
 602                 );
 603                 if ( $res && sqlsrv_has_rows( $res ) ) {
 604                         // There is an identity for this table.
 605                         $identityArr = sqlsrv_fetch_array( $res, SQLSRV_FETCH_ASSOC );
 606                         $identity = array_pop( $identityArr );
 607                 }
 608                 sqlsrv_free_stmt( $res );
 609
 610                 // Determine binary/varbinary fields so we can encode data as a hex string like 0xABCDEF
 611                 $binaryColumns = $this->getBinaryColumns( $table );
 612
 613                 // INSERT IGNORE is not supported by SQL Server
 614                 // remove IGNORE from options list and set ignore flag to true
 615                 if ( in_array( 'IGNORE', $options ) ) {
 616                         $options = array_diff( $options, [ 'IGNORE' ] );
 617                         $this->mIgnoreDupKeyErrors = true;
 618                 }
 619
 620                 $ret = null;
 621                 foreach ( $arrToInsert as $a ) {
 622                         // start out with empty identity column, this is so we can return
 623                         // it as a result of the INSERT logic
 624                         $sqlPre = '';
 625                         $sqlPost = '';
 626                         $identityClause = '';
 627
 628                         // if we have an identity column
 629                         if ( $identity ) {
 630                                 // iterate through
 631                                 foreach ( $a as $k => $v ) {
 632                                         if ( $k == $identity ) {
 633                                                 if ( !is_null( $v ) ) {
 634                                                         // there is a value being passed to us,
 635                                                         // we need to turn on and off inserted identity
 636                                                         $sqlPre = "SET IDENTITY_INSERT $table ON;";
 637                                                         $sqlPost = ";SET IDENTITY_INSERT $table OFF;";
 638                                                 } else {
 639                                                         // we can't insert NULL into an identity column,
 640                                                         // so remove the column from the insert.
 641                                                         unset( $a[$k] );
 642                                                 }
 643                                         }
 644                                 }
 645
 646                                 // we want to output an identity column as result
 647                                 $identityClause = "OUTPUT INSERTED.$identity ";
 648                         }
 649
 650                         $keys = array_keys( $a );
 651
 652                         // Build the actual query
 653                         $sql = $sqlPre . 'INSERT ' . implode( ' ', $options ) .
 654                                 " INTO $table (" . implode( ',', $keys ) . ") $identityClause VALUES (";
 655
 656                         $first = true;
 657                         foreach ( $a as $key => $value ) {
 658                                 if ( isset( $binaryColumns[$key] ) ) {
 659                                         $value = new MssqlBlob( $value );
 660                                 }
 661                                 if ( $first ) {
 662                                         $first = false;
 663                                 } else {
 664                                         $sql .= ',';
 665                                 }
 666                                 if ( is_null( $value ) ) {
 667                                         $sql .= 'null';
 668                                 } elseif ( is_array( $value ) || is_object( $value ) ) {
 669                                         if ( is_object( $value ) && $value instanceof Blob ) {
 670                                                 $sql .= $this->addQuotes( $value );
 671                                         } else {
 672                                                 $sql .= $this->addQuotes( serialize( $value ) );
 673                                         }
 674                                 } else {
 675                                         $sql .= $this->addQuotes( $value );
 676                                 }
 677                         }
 678                         $sql .= ')' . $sqlPost;
 679
 680                         // Run the query
 681                         $this->mScrollableCursor = false;
 682                         try {
 683                                 $ret = $this->query( $sql );
 684                         } catch ( Exception $e ) {
 685                                 $this->mScrollableCursor = true;
 686                                 $this->mIgnoreDupKeyErrors = false;
 687                                 throw $e;
 688                         }
 689                         $this->mScrollableCursor = true;
 690
 691                         if ( $ret instanceof ResultWrapper && !is_null( $identity ) ) {
 692                                 // Then we want to get the identity column value we were assigned and save it off
 693                                 $row = $ret->fetchObject();
 694                                 if ( is_object( $row ) ) {
 695                                         $this->mInsertId = $row->$identity;
 696                                         // It seems that mAffectedRows is -1 sometimes when OUTPUT INSERTED.identity is
 697                                         // used if we got an identity back, we know for sure a row was affected, so
 698                                         // adjust that here
 699                                         if ( $this->mAffectedRows == -1 ) {
 700                                                 $this->mAffectedRows = 1;
 701                                         }
 702                                 }
 703                         }
 704                 }
 705
 706                 $this->mIgnoreDupKeyErrors = false;
 707
 708                 return $ret;
 709         }
 710
 711         /**
 712          * INSERT SELECT wrapper
 713          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 714          * Source items may be literals rather than field names, but strings should
 715          * be quoted with Database::addQuotes().
 716          * @param string $destTable
 717          * @param array|string $srcTable May be an array of tables.
 718          * @param array $varMap
 719          * @param array $conds May be "*" to copy the whole table.
 720          * @param string $fname
 721          * @param array $insertOptions
 722          * @param array $selectOptions
 723          * @return null|ResultWrapper
 724          * @throws Exception
 725          */
 726         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 727                 $insertOptions = [], $selectOptions = []
 728         ) {
 729                 $this->mScrollableCursor = false;
 730                 try {
 731                         $ret = parent::nativeInsertSelect(
 732                                 $destTable,
 733                                 $srcTable,
 734                                 $varMap,
 735                                 $conds,
 736                                 $fname,
 737                                 $insertOptions,
 738                                 $selectOptions
 739                         );
 740                 } catch ( Exception $e ) {
 741                         $this->mScrollableCursor = true;
 742                         throw $e;
 743                 }
 744                 $this->mScrollableCursor = true;
 745
 746                 return $ret;
 747         }
 748
 749         /**
 750          * UPDATE wrapper. Takes a condition array and a SET array.
 751          *
 752          * @param string $table Name of the table to UPDATE. This will be passed through
 753          *                Database::tableName().
 754          *
 755          * @param array $values An array of values to SET. For each array element,
 756          *                the key gives the field name, and the value gives the data
 757          *                to set that field to. The data will be quoted by
 758          *                Database::addQuotes().
 759          *
 760          * @param array $conds An array of conditions (WHERE). See
 761          *                Database::select() for the details of the format of
 762          *                condition arrays. Use '*' to update all rows.
 763          *
 764          * @param string $fname The function name of the caller (from __METHOD__),
 765          *                for logging and profiling.
 766          *
 767          * @param array $options An array of UPDATE options, can be:
 768          *                   - IGNORE: Ignore unique key conflicts
 769          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
 770          * @return bool
 771          * @throws DBUnexpectedError
 772          * @throws Exception
 773          */
 774         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
 775                 $table = $this->tableName( $table );
 776                 $binaryColumns = $this->getBinaryColumns( $table );
 777
 778                 $opts = $this->makeUpdateOptions( $options );
 779                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET, $binaryColumns );
 780
 781                 if ( $conds !== [] && $conds !== '*' ) {
 782                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND, $binaryColumns );
 783                 }
 784
 785                 $this->mScrollableCursor = false;
 786                 try {
 787                         $this->query( $sql );
 788                 } catch ( Exception $e ) {
 789                         $this->mScrollableCursor = true;
 790                         throw $e;
 791                 }
 792                 $this->mScrollableCursor = true;
 793                 return true;
 794         }
 795
 796         /**
 797          * Makes an encoded list of strings from an array
 798          * @param array $a Containing the data
 799          * @param int $mode Constant
 800          *      - LIST_COMMA:          comma separated, no field names
 801          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
 802          *        the documentation for $conds in Database::select().
 803          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
 804          *      - LIST_SET:            comma separated with field names, like a SET clause
 805          *      - LIST_NAMES:          comma separated field names
 806          * @param array $binaryColumns Contains a list of column names that are binary types
 807          *      This is a custom parameter only present for MS SQL.
 808          *
 809          * @throws DBUnexpectedError
 810          * @return string
 811          */
 812         public function makeList( $a, $mode = LIST_COMMA, $binaryColumns = [] ) {
 813                 if ( !is_array( $a ) ) {
 814                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
 815                 }
 816
 817                 if ( $mode != LIST_NAMES ) {
 818                         // In MS SQL, values need to be specially encoded when they are
 819                         // inserted into binary fields. Perform this necessary encoding
 820                         // for the specified set of columns.
 821                         foreach ( array_keys( $a ) as $field ) {
 822                                 if ( !isset( $binaryColumns[$field] ) ) {
 823                                         continue;
 824                                 }
 825
 826                                 if ( is_array( $a[$field] ) ) {
 827                                         foreach ( $a[$field] as &$v ) {
 828                                                 $v = new MssqlBlob( $v );
 829                                         }
 830                                         unset( $v );
 831                                 } else {
 832                                         $a[$field] = new MssqlBlob( $a[$field] );
 833                                 }
 834                         }
 835                 }
 836
 837                 return parent::makeList( $a, $mode );
 838         }
 839
 840         /**
 841          * @param string $table
 842          * @param string $field
 843          * @return int Returns the size of a text field, or -1 for "unlimited"
 844          */
 845         public function textFieldSize( $table, $field ) {
 846                 $table = $this->tableName( $table );
 847                 $sql = "SELECT CHARACTER_MAXIMUM_LENGTH,DATA_TYPE FROM INFORMATION_SCHEMA.Columns
 848                         WHERE TABLE_NAME = '$table' AND COLUMN_NAME = '$field'";
 849                 $res = $this->query( $sql );
 850                 $row = $this->fetchRow( $res );
 851                 $size = -1;
 852                 if ( strtolower( $row['DATA_TYPE'] ) != 'text' ) {
 853                         $size = $row['CHARACTER_MAXIMUM_LENGTH'];
 854                 }
 855
 856                 return $size;
 857         }
 858
 859         /**
 860          * Construct a LIMIT query with optional offset
 861          * This is used for query pages
 862          *
 863          * @param string $sql SQL query we will append the limit too
 864          * @param int $limit The SQL limit
 865          * @param bool|int $offset The SQL offset (default false)
 866          * @return array|string
 867          * @throws DBUnexpectedError
 868          */
 869         public function limitResult( $sql, $limit, $offset = false ) {
 870                 if ( $offset === false || $offset == 0 ) {
 871                         if ( strpos( $sql, "SELECT" ) === false ) {
 872                                 return "TOP {$limit} " . $sql;
 873                         } else {
 874                                 return preg_replace( '/\bSELECT(\s+DISTINCT)?\b/Dsi',
 875                                         'SELECT$1 TOP ' . $limit, $sql, 1 );
 876                         }
 877                 } else {
 878                         // This one is fun, we need to pull out the select list as well as any ORDER BY clause
 879                         $select = $orderby = [];
 880                         $s1 = preg_match( '#SELECT\s+(.+?)\s+FROM#Dis', $sql, $select );
 881                         $s2 = preg_match( '#(ORDER BY\s+.+?)(\s*FOR XML .*)?$#Dis', $sql, $orderby );
 882                         $postOrder = '';
 883                         $first = $offset + 1;
 884                         $last = $offset + $limit;
 885                         $sub1 = 'sub_' . $this->mSubqueryId;
 886                         $sub2 = 'sub_' . ( $this->mSubqueryId + 1 );
 887                         $this->mSubqueryId += 2;
 888                         if ( !$s1 ) {
 889                                 // wat
 890                                 throw new DBUnexpectedError( $this, "Attempting to LIMIT a non-SELECT query\n" );
 891                         }
 892                         if ( !$s2 ) {
 893                                 // no ORDER BY
 894                                 $overOrder = 'ORDER BY (SELECT 1)';
 895                         } else {
 896                                 if ( !isset( $orderby[2] ) || !$orderby[2] ) {
 897                                         // don't need to strip it out if we're using a FOR XML clause
 898                                         $sql = str_replace( $orderby[1], '', $sql );
 899                                 }
 900                                 $overOrder = $orderby[1];
 901                                 $postOrder = ' ' . $overOrder;
 902                         }
 903                         $sql = "SELECT {$select[1]}
 904                                         FROM (
 905                                                 SELECT ROW_NUMBER() OVER({$overOrder}) AS rowNumber, *
 906                                                 FROM ({$sql}) {$sub1}
 907                                         ) {$sub2}
 908                                         WHERE rowNumber BETWEEN {$first} AND {$last}{$postOrder}";
 909
 910                         return $sql;
 911                 }
 912         }
 913
 914         /**
 915          * If there is a limit clause, parse it, strip it, and pass the remaining
 916          * SQL through limitResult() with the appropriate parameters. Not the
 917          * prettiest solution, but better than building a whole new parser. This
 918          * exists becase there are still too many extensions that don't use dynamic
 919          * sql generation.
 920          *
 921          * @param string $sql
 922          * @return array|mixed|string
 923          */
 924         public function LimitToTopN( $sql ) {
 925                 // Matches: LIMIT {[offset,] row_count | row_count OFFSET offset}
 926                 $pattern = '/\bLIMIT\s+((([0-9]+)\s*,\s*)?([0-9]+)(\s+OFFSET\s+([0-9]+))?)/i';
 927                 if ( preg_match( $pattern, $sql, $matches ) ) {
 928                         $row_count = $matches[4];
 929                         $offset = $matches[3] ?: $matches[6] ?: false;
 930
 931                         // strip the matching LIMIT clause out
 932                         $sql = str_replace( $matches[0], '', $sql );
 933
 934                         return $this->limitResult( $sql, $row_count, $offset );
 935                 }
 936
 937                 return $sql;
 938         }
 939
 940         /**
 941          * @return string Wikitext of a link to the server software's web site
 942          */
 943         public function getSoftwareLink() {
 944                 return "[{{int:version-db-mssql-url}} MS SQL Server]";
 945         }
 946
 947         /**
 948          * @return string Version information from the database
 949          */
 950         public function getServerVersion() {
 951                 $server_info = sqlsrv_server_info( $this->mConn );
 952                 $version = 'Error';
 953                 if ( isset( $server_info['SQLServerVersion'] ) ) {
 954                         $version = $server_info['SQLServerVersion'];
 955                 }
 956
 957                 return $version;
 958         }
 959
 960         /**
 961          * @param string $table
 962          * @param string $fname
 963          * @return bool
 964          */
 965         public function tableExists( $table, $fname = __METHOD__ ) {
 966                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
 967
 968                 if ( $db !== false ) {
 969                         // remote database
 970                         $this->queryLogger->error( "Attempting to call tableExists on a remote table" );
 971                         return false;
 972                 }
 973
 974                 if ( $schema === false ) {
 975                         $schema = $this->mSchema;
 976                 }
 977
 978                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.TABLES
 979                         WHERE TABLE_TYPE = 'BASE TABLE'
 980                         AND TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table'" );
 981
 982                 if ( $res->numRows() ) {
 983                         return true;
 984                 } else {
 985                         return false;
 986                 }
 987         }
 988
 989         /**
 990          * Query whether a given column exists in the mediawiki schema
 991          * @param string $table
 992          * @param string $field
 993          * @param string $fname
 994          * @return bool
 995          */
 996         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
 997                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
 998
 999                 if ( $db !== false ) {
1000                         // remote database
1001                         $this->queryLogger->error( "Attempting to call fieldExists on a remote table" );
1002                         return false;
1003                 }
1004
1005                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS
1006                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1007
1008                 if ( $res->numRows() ) {
1009                         return true;
1010                 } else {
1011                         return false;
1012                 }
1013         }
1014
1015         public function fieldInfo( $table, $field ) {
1016                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
1017
1018                 if ( $db !== false ) {
1019                         // remote database
1020                         $this->queryLogger->error( "Attempting to call fieldInfo on a remote table" );
1021                         return false;
1022                 }
1023
1024                 $res = $this->query( "SELECT * FROM INFORMATION_SCHEMA.COLUMNS
1025                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1026
1027                 $meta = $res->fetchRow();
1028                 if ( $meta ) {
1029                         return new MssqlField( $meta );
1030                 }
1031
1032                 return false;
1033         }
1034
1035         /**
1036          * Begin a transaction, committing any previously open transaction
1037          * @param string $fname
1038          */
1039         protected function doBegin( $fname = __METHOD__ ) {
1040                 sqlsrv_begin_transaction( $this->mConn );
1041                 $this->mTrxLevel = 1;
1042         }
1043
1044         /**
1045          * End a transaction
1046          * @param string $fname
1047          */
1048         protected function doCommit( $fname = __METHOD__ ) {
1049                 sqlsrv_commit( $this->mConn );
1050                 $this->mTrxLevel = 0;
1051         }
1052
1053         /**
1054          * Rollback a transaction.
1055          * No-op on non-transactional databases.
1056          * @param string $fname
1057          */
1058         protected function doRollback( $fname = __METHOD__ ) {
1059                 sqlsrv_rollback( $this->mConn );
1060                 $this->mTrxLevel = 0;
1061         }
1062
1063         /**
1064          * @param string $s
1065          * @return string
1066          */
1067         public function strencode( $s ) {
1068                 // Should not be called by us
1069
1070                 return str_replace( "'", "''", $s );
1071         }
1072
1073         /**
1074          * @param string|int|null|bool|Blob $s
1075          * @return string|int
1076          */
1077         public function addQuotes( $s ) {
1078                 if ( $s instanceof MssqlBlob ) {
1079                         return $s->fetch();
1080                 } elseif ( $s instanceof Blob ) {
1081                         // this shouldn't really ever be called, but it's here if needed
1082                         // (and will quite possibly make the SQL error out)
1083                         $blob = new MssqlBlob( $s->fetch() );
1084                         return $blob->fetch();
1085                 } else {
1086                         if ( is_bool( $s ) ) {
1087                                 $s = $s ? 1 : 0;
1088                         }
1089                         return parent::addQuotes( $s );
1090                 }
1091         }
1092
1093         /**
1094          * @param string $s
1095          * @return string
1096          */
1097         public function addIdentifierQuotes( $s ) {
1098                 // http://msdn.microsoft.com/en-us/library/aa223962.aspx
1099                 return '[' . $s . ']';
1100         }
1101
1102         /**
1103          * @param string $name
1104          * @return bool
1105          */
1106         public function isQuotedIdentifier( $name ) {
1107                 return strlen( $name ) && $name[0] == '[' && substr( $name, -1, 1 ) == ']';
1108         }
1109
1110         /**
1111          * MS SQL supports more pattern operators than other databases (ex: [,],^)
1112          *
1113          * @param string $s
1114          * @return string
1115          */
1116         protected function escapeLikeInternal( $s ) {
1117                 return addcslashes( $s, '\%_[]^' );
1118         }
1119
1120         /**
1121          * MS SQL requires specifying the escape character used in a LIKE query
1122          * or using Square brackets to surround characters that are to be escaped
1123          * https://msdn.microsoft.com/en-us/library/ms179859.aspx
1124          * Here we take the Specify-Escape-Character approach since it's less
1125          * invasive, renders a query that is closer to other DB's and better at
1126          * handling square bracket escaping
1127          *
1128          * @return string Fully built LIKE statement
1129          */
1130         public function buildLike() {
1131                 $params = func_get_args();
1132                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1133                         $params = $params[0];
1134                 }
1135
1136                 return parent::buildLike( $params ) . " ESCAPE '\' ";
1137         }
1138
1139         /**
1140          * @param string $db
1141          * @return bool
1142          */
1143         public function selectDB( $db ) {
1144                 try {
1145                         $this->mDBname = $db;
1146                         $this->query( "USE $db" );
1147                         return true;
1148                 } catch ( Exception $e ) {
1149                         return false;
1150                 }
1151         }
1152
1153         /**
1154          * @param array $options An associative array of options to be turned into
1155          *   an SQL query, valid keys are listed in the function.
1156          * @return array
1157          */
1158         public function makeSelectOptions( $options ) {
1159                 $tailOpts = '';
1160                 $startOpts = '';
1161
1162                 $noKeyOptions = [];
1163                 foreach ( $options as $key => $option ) {
1164                         if ( is_numeric( $key ) ) {
1165                                 $noKeyOptions[$option] = true;
1166                         }
1167                 }
1168
1169                 $tailOpts .= $this->makeGroupByWithHaving( $options );
1170
1171                 $tailOpts .= $this->makeOrderBy( $options );
1172
1173                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1174                         $startOpts .= 'DISTINCT';
1175                 }
1176
1177                 if ( isset( $noKeyOptions['FOR XML'] ) ) {
1178                         // used in group concat field emulation
1179                         $tailOpts .= " FOR XML PATH('')";
1180                 }
1181
1182                 // we want this to be compatible with the output of parent::makeSelectOptions()
1183                 return [ $startOpts, '', $tailOpts, '', '' ];
1184         }
1185
1186         public function getType() {
1187                 return 'mssql';
1188         }
1189
1190         /**
1191          * @param array $stringList
1192          * @return string
1193          */
1194         public function buildConcat( $stringList ) {
1195                 return implode( ' + ', $stringList );
1196         }
1197
1198         /**
1199          * Build a GROUP_CONCAT or equivalent statement for a query.
1200          * MS SQL doesn't have GROUP_CONCAT so we emulate it with other stuff (and boy is it nasty)
1201          *
1202          * This is useful for combining a field for several rows into a single string.
1203          * NULL values will not appear in the output, duplicated values will appear,
1204          * and the resulting delimiter-separated values have no defined sort order.
1205          * Code using the results may need to use the PHP unique() or sort() methods.
1206          *
1207          * @param string $delim Glue to bind the results together
1208          * @param string|array $table Table name
1209          * @param string $field Field name
1210          * @param string|array $conds Conditions
1211          * @param string|array $join_conds Join conditions
1212          * @return string SQL text
1213          * @since 1.23
1214          */
1215         public function buildGroupConcatField( $delim, $table, $field, $conds = '',
1216                 $join_conds = []
1217         ) {
1218                 $gcsq = 'gcsq_' . $this->mSubqueryId;
1219                 $this->mSubqueryId++;
1220
1221                 $delimLen = strlen( $delim );
1222                 $fld = "{$field} + {$this->addQuotes( $delim )}";
1223                 $sql = "(SELECT LEFT({$field}, LEN({$field}) - {$delimLen}) FROM ("
1224                         . $this->selectSQLText( $table, $fld, $conds, null, [ 'FOR XML' ], $join_conds )
1225                         . ") {$gcsq} ({$field}))";
1226
1227                 return $sql;
1228         }
1229
1230         /**
1231          * Returns an associative array for fields that are of type varbinary, binary, or image
1232          * $table can be either a raw table name or passed through tableName() first
1233          * @param string $table
1234          * @return array
1235          */
1236         private function getBinaryColumns( $table ) {
1237                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1238                 $tableRaw = array_pop( $tableRawArr );
1239
1240                 if ( $this->mBinaryColumnCache === null ) {
1241                         $this->populateColumnCaches();
1242                 }
1243
1244                 return isset( $this->mBinaryColumnCache[$tableRaw] )
1245                         ? $this->mBinaryColumnCache[$tableRaw]
1246                         : [];
1247         }
1248
1249         /**
1250          * @param string $table
1251          * @return array
1252          */
1253         private function getBitColumns( $table ) {
1254                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1255                 $tableRaw = array_pop( $tableRawArr );
1256
1257                 if ( $this->mBitColumnCache === null ) {
1258                         $this->populateColumnCaches();
1259                 }
1260
1261                 return isset( $this->mBitColumnCache[$tableRaw] )
1262                         ? $this->mBitColumnCache[$tableRaw]
1263                         : [];
1264         }
1265
1266         private function populateColumnCaches() {
1267                 $res = $this->select( 'INFORMATION_SCHEMA.COLUMNS', '*',
1268                         [
1269                                 'TABLE_CATALOG' => $this->mDBname,
1270                                 'TABLE_SCHEMA' => $this->mSchema,
1271                                 'DATA_TYPE' => [ 'varbinary', 'binary', 'image', 'bit' ]
1272                         ] );
1273
1274                 $this->mBinaryColumnCache = [];
1275                 $this->mBitColumnCache = [];
1276                 foreach ( $res as $row ) {
1277                         if ( $row->DATA_TYPE == 'bit' ) {
1278                                 $this->mBitColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1279                         } else {
1280                                 $this->mBinaryColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1281                         }
1282                 }
1283         }
1284
1285         /**
1286          * @param string $name
1287          * @param string $format
1288          * @return string
1289          */
1290         function tableName( $name, $format = 'quoted' ) {
1291                 # Replace reserved words with better ones
1292                 switch ( $name ) {
1293                         case 'user':
1294                                 return $this->realTableName( 'mwuser', $format );
1295                         default:
1296                                 return $this->realTableName( $name, $format );
1297                 }
1298         }
1299
1300         /**
1301          * call this instead of tableName() in the updater when renaming tables
1302          * @param string $name
1303          * @param string $format One of quoted, raw, or split
1304          * @return string
1305          */
1306         function realTableName( $name, $format = 'quoted' ) {
1307                 $table = parent::tableName( $name, $format );
1308                 if ( $format == 'split' ) {
1309                         // Used internally, we want the schema split off from the table name and returned
1310                         // as a list with 3 elements (database, schema, table)
1311                         $table = explode( '.', $table );
1312                         while ( count( $table ) < 3 ) {
1313                                 array_unshift( $table, false );
1314                         }
1315                 }
1316                 return $table;
1317         }
1318
1319         /**
1320          * Delete a table
1321          * @param string $tableName
1322          * @param string $fName
1323          * @return bool|ResultWrapper
1324          * @since 1.18
1325          */
1326         public function dropTable( $tableName, $fName = __METHOD__ ) {
1327                 if ( !$this->tableExists( $tableName, $fName ) ) {
1328                         return false;
1329                 }
1330
1331                 // parent function incorrectly appends CASCADE, which we don't want
1332                 $sql = "DROP TABLE " . $this->tableName( $tableName );
1333
1334                 return $this->query( $sql, $fName );
1335         }
1336
1337         /**
1338          * Called in the installer and updater.
1339          * Probably doesn't need to be called anywhere else in the codebase.
1340          * @param bool|null $value
1341          * @return bool|null
1342          */
1343         public function prepareStatements( $value = null ) {
1344                 $old = $this->mPrepareStatements;
1345                 if ( $value !== null ) {
1346                         $this->mPrepareStatements = $value;
1347                 }
1348
1349                 return $old;
1350         }
1351
1352         /**
1353          * Called in the installer and updater.
1354          * Probably doesn't need to be called anywhere else in the codebase.
1355          * @param bool|null $value
1356          * @return bool|null
1357          */
1358         public function scrollableCursor( $value = null ) {
1359                 $old = $this->mScrollableCursor;
1360                 if ( $value !== null ) {
1361                         $this->mScrollableCursor = $value;
1362                 }
1363
1364                 return $old;
1365         }
1366 }
1367
1368 class_alias( DatabaseMssql::class, 'DatabaseMssql' );