includes/libs/rdbms/database/DatabaseMssql.php

   1 <?php
   2 /**
   3  * This is the MS SQL Server Native database abstraction layer.
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License along
  16  * with this program; if not, write to the Free Software Foundation, Inc.,
  17  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  18  * http://www.gnu.org/copyleft/gpl.html
  19  *
  20  * @file
  21  * @ingroup Database
  22  * @author Joel Penner <a-joelpe at microsoft dot com>
  23  * @author Chris Pucci <a-cpucci at microsoft dot com>
  24  * @author Ryan Biesemeyer <v-ryanbi at microsoft dot com>
  25  * @author Ryan Schmidt <skizzerz at gmail dot com>
  26  */
  27
  28 namespace Wikimedia\Rdbms;
  29
  30 use Wikimedia;
  31 use Exception;
  32 use stdClass;
  33
  34 /**
  35  * @ingroup Database
  36  */
  37 class DatabaseMssql extends Database {
  38         /** @var int */
  39         protected $serverPort;
  40         /** @var bool */
  41         protected $useWindowsAuth = false;
  42         /** @var int|null */
  43         protected $lastInsertId = null;
  44         /** @var int|null */
  45         protected $lastAffectedRowCount = null;
  46         /** @var int */
  47         protected $subqueryId = 0;
  48         /** @var bool */
  49         protected $scrollableCursor = true;
  50         /** @var bool */
  51         protected $prepareStatements = true;
  52         /** @var stdClass[][]|null */
  53         protected $binaryColumnCache = null;
  54         /** @var stdClass[][]|null */
  55         protected $bitColumnCache = null;
  56         /** @var bool */
  57         protected $ignoreDupKeyErrors = false;
  58         /** @var string[] */
  59         protected $ignoreErrors = [];
  60
  61         public function implicitGroupby() {
  62                 return false;
  63         }
  64
  65         public function implicitOrderby() {
  66                 return false;
  67         }
  68
  69         public function unionSupportsOrderAndLimit() {
  70                 return false;
  71         }
  72
  73         public function __construct( array $params ) {
  74                 $this->serverPort = $params['port'];
  75                 $this->useWindowsAuth = $params['UseWindowsAuth'];
  76
  77                 parent::__construct( $params );
  78         }
  79
  80         /**
  81          * Usually aborts on failure
  82          * @param string $server
  83          * @param string $user
  84          * @param string $password
  85          * @param string $dbName
  86          * @throws DBConnectionError
  87          * @return bool|resource|null
  88          */
  89         public function open( $server, $user, $password, $dbName ) {
  90                 # Test for driver support, to avoid suppressed fatal error
  91                 if ( !function_exists( 'sqlsrv_connect' ) ) {
  92                         throw new DBConnectionError(
  93                                 $this,
  94                                 "Microsoft SQL Server Native (sqlsrv) functions missing.
  95                                 You can download the driver from: http://go.microsoft.com/fwlink/?LinkId=123470\n"
  96                         );
  97                 }
  98
  99                 # e.g. the class is being loaded
 100                 if ( !strlen( $user ) ) {
 101                         return null;
 102                 }
 103
 104                 $this->close();
 105                 $this->server = $server;
 106                 $this->user = $user;
 107                 $this->password = $password;
 108                 $this->dbName = $dbName;
 109
 110                 $connectionInfo = [];
 111
 112                 if ( $dbName ) {
 113                         $connectionInfo['Database'] = $dbName;
 114                 }
 115
 116                 // Decide which auth scenerio to use
 117                 // if we are using Windows auth, then don't add credentials to $connectionInfo
 118                 if ( !$this->useWindowsAuth ) {
 119                         $connectionInfo['UID'] = $user;
 120                         $connectionInfo['PWD'] = $password;
 121                 }
 122
 123                 Wikimedia\suppressWarnings();
 124                 $this->conn = sqlsrv_connect( $server, $connectionInfo );
 125                 Wikimedia\restoreWarnings();
 126
 127                 if ( $this->conn === false ) {
 128                         throw new DBConnectionError( $this, $this->lastError() );
 129                 }
 130
 131                 $this->opened = true;
 132
 133                 return $this->conn;
 134         }
 135
 136         /**
 137          * Closes a database connection, if it is open
 138          * Returns success, true if already closed
 139          * @return bool
 140          */
 141         protected function closeConnection() {
 142                 return sqlsrv_close( $this->conn );
 143         }
 144
 145         /**
 146          * @param bool|MssqlResultWrapper|resource $result
 147          * @return bool|MssqlResultWrapper
 148          */
 149         protected function resultObject( $result ) {
 150                 if ( !$result ) {
 151                         return false;
 152                 } elseif ( $result instanceof MssqlResultWrapper ) {
 153                         return $result;
 154                 } elseif ( $result === true ) {
 155                         // Successful write query
 156                         return $result;
 157                 } else {
 158                         return new MssqlResultWrapper( $this, $result );
 159                 }
 160         }
 161
 162         /**
 163          * @param string $sql
 164          * @return bool|MssqlResultWrapper|resource
 165          * @throws DBUnexpectedError
 166          */
 167         protected function doQuery( $sql ) {
 168                 // several extensions seem to think that all databases support limits
 169                 // via LIMIT N after the WHERE clause, but  MSSQL uses SELECT TOP N,
 170                 // so to catch any of those extensions we'll do a quick check for a
 171                 // LIMIT clause and pass $sql through $this->LimitToTopN() which parses
 172                 // the LIMIT clause and passes the result to $this->limitResult();
 173                 if ( preg_match( '/\bLIMIT\s*/i', $sql ) ) {
 174                         // massage LIMIT -> TopN
 175                         $sql = $this->LimitToTopN( $sql );
 176                 }
 177
 178                 // MSSQL doesn't have EXTRACT(epoch FROM XXX)
 179                 if ( preg_match( '#\bEXTRACT\s*?\(\s*?EPOCH\s+FROM\b#i', $sql, $matches ) ) {
 180                         // This is same as UNIX_TIMESTAMP, we need to calc # of seconds from 1970
 181                         $sql = str_replace( $matches[0], "DATEDIFF(s,CONVERT(datetime,'1/1/1970'),", $sql );
 182                 }
 183
 184                 // perform query
 185
 186                 // SQLSRV_CURSOR_STATIC is slower than SQLSRV_CURSOR_CLIENT_BUFFERED (one of the two is
 187                 // needed if we want to be able to seek around the result set), however CLIENT_BUFFERED
 188                 // has a bug in the sqlsrv driver where wchar_t types (such as nvarchar) that are empty
 189                 // strings make php throw a fatal error "Severe error translating Unicode"
 190                 if ( $this->scrollableCursor ) {
 191                         $scrollArr = [ 'Scrollable' => SQLSRV_CURSOR_STATIC ];
 192                 } else {
 193                         $scrollArr = [];
 194                 }
 195
 196                 if ( $this->prepareStatements ) {
 197                         // we do prepare + execute so we can get its field metadata for later usage if desired
 198                         $stmt = sqlsrv_prepare( $this->conn, $sql, [], $scrollArr );
 199                         $success = sqlsrv_execute( $stmt );
 200                 } else {
 201                         $stmt = sqlsrv_query( $this->conn, $sql, [], $scrollArr );
 202                         $success = (bool)$stmt;
 203                 }
 204
 205                 // Make a copy to ensure what we add below does not get reflected in future queries
 206                 $ignoreErrors = $this->ignoreErrors;
 207
 208                 if ( $this->ignoreDupKeyErrors ) {
 209                         // ignore duplicate key errors
 210                         // this emulates INSERT IGNORE in MySQL
 211                         $ignoreErrors[] = '2601'; // duplicate key error caused by unique index
 212                         $ignoreErrors[] = '2627'; // duplicate key error caused by primary key
 213                         $ignoreErrors[] = '3621'; // generic "the statement has been terminated" error
 214                 }
 215
 216                 if ( $success === false ) {
 217                         $errors = sqlsrv_errors();
 218                         $success = true;
 219
 220                         foreach ( $errors as $err ) {
 221                                 if ( !in_array( $err['code'], $ignoreErrors ) ) {
 222                                         $success = false;
 223                                         break;
 224                                 }
 225                         }
 226
 227                         if ( $success === false ) {
 228                                 return false;
 229                         }
 230                 }
 231                 // remember number of rows affected
 232                 $this->lastAffectedRowCount = sqlsrv_rows_affected( $stmt );
 233
 234                 return $stmt;
 235         }
 236
 237         public function freeResult( $res ) {
 238                 if ( $res instanceof ResultWrapper ) {
 239                         $res = $res->result;
 240                 }
 241
 242                 sqlsrv_free_stmt( $res );
 243         }
 244
 245         /**
 246          * @param MssqlResultWrapper $res
 247          * @return stdClass
 248          */
 249         public function fetchObject( $res ) {
 250                 // $res is expected to be an instance of MssqlResultWrapper here
 251                 return $res->fetchObject();
 252         }
 253
 254         /**
 255          * @param MssqlResultWrapper $res
 256          * @return array
 257          */
 258         public function fetchRow( $res ) {
 259                 return $res->fetchRow();
 260         }
 261
 262         /**
 263          * @param mixed $res
 264          * @return int
 265          */
 266         public function numRows( $res ) {
 267                 if ( $res instanceof ResultWrapper ) {
 268                         $res = $res->result;
 269                 }
 270
 271                 $ret = sqlsrv_num_rows( $res );
 272
 273                 if ( $ret === false ) {
 274                         // we cannot get an amount of rows from this cursor type
 275                         // has_rows returns bool true/false if the result has rows
 276                         $ret = (int)sqlsrv_has_rows( $res );
 277                 }
 278
 279                 return $ret;
 280         }
 281
 282         /**
 283          * @param mixed $res
 284          * @return int
 285          */
 286         public function numFields( $res ) {
 287                 if ( $res instanceof ResultWrapper ) {
 288                         $res = $res->result;
 289                 }
 290
 291                 return sqlsrv_num_fields( $res );
 292         }
 293
 294         /**
 295          * @param mixed $res
 296          * @param int $n
 297          * @return int
 298          */
 299         public function fieldName( $res, $n ) {
 300                 if ( $res instanceof ResultWrapper ) {
 301                         $res = $res->result;
 302                 }
 303
 304                 return sqlsrv_field_metadata( $res )[$n]['Name'];
 305         }
 306
 307         /**
 308          * This must be called after nextSequenceVal
 309          * @return int|null
 310          */
 311         public function insertId() {
 312                 return $this->lastInsertId;
 313         }
 314
 315         /**
 316          * @param MssqlResultWrapper $res
 317          * @param int $row
 318          * @return bool
 319          */
 320         public function dataSeek( $res, $row ) {
 321                 return $res->seek( $row );
 322         }
 323
 324         /**
 325          * @return string
 326          */
 327         public function lastError() {
 328                 $strRet = '';
 329                 $retErrors = sqlsrv_errors( SQLSRV_ERR_ALL );
 330                 if ( $retErrors != null ) {
 331                         foreach ( $retErrors as $arrError ) {
 332                                 $strRet .= $this->formatError( $arrError ) . "\n";
 333                         }
 334                 } else {
 335                         $strRet = "No errors found";
 336                 }
 337
 338                 return $strRet;
 339         }
 340
 341         /**
 342          * @param array $err
 343          * @return string
 344          */
 345         private function formatError( $err ) {
 346                 return '[SQLSTATE ' .
 347                         $err['SQLSTATE'] . '][Error Code ' . $err['code'] . ']' . $err['message'];
 348         }
 349
 350         /**
 351          * @return string|int
 352          */
 353         public function lastErrno() {
 354                 $err = sqlsrv_errors( SQLSRV_ERR_ALL );
 355                 if ( $err !== null && isset( $err[0] ) ) {
 356                         return $err[0]['code'];
 357                 } else {
 358                         return 0;
 359                 }
 360         }
 361
 362         protected function wasKnownStatementRollbackError() {
 363                 $errors = sqlsrv_errors( SQLSRV_ERR_ALL );
 364                 if ( !$errors ) {
 365                         return false;
 366                 }
 367                 // The transaction vs statement rollback behavior depends on XACT_ABORT, so make sure
 368                 // that the "statement has been terminated" error (3621) is specifically present.
 369                 // https://docs.microsoft.com/en-us/sql/t-sql/statements/set-xact-abort-transact-sql
 370                 $statementOnly = false;
 371                 $codeWhitelist = [ '2601', '2627', '547' ];
 372                 foreach ( $errors as $error ) {
 373                         if ( $error['code'] == '3621' ) {
 374                                 $statementOnly = true;
 375                         } elseif ( !in_array( $error['code'], $codeWhitelist ) ) {
 376                                 $statementOnly = false;
 377                                 break;
 378                         }
 379                 }
 380
 381                 return $statementOnly;
 382         }
 383
 384         /**
 385          * @return int
 386          */
 387         protected function fetchAffectedRowCount() {
 388                 return $this->lastAffectedRowCount;
 389         }
 390
 391         /**
 392          * SELECT wrapper
 393          *
 394          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 395          * @param mixed $vars Array or string, field name(s) to be retrieved
 396          * @param mixed $conds Array or string, condition(s) for WHERE
 397          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 398          * @param array $options Associative array of options (e.g.
 399          *   [ 'GROUP BY' => 'page_title' ]), see Database::makeSelectOptions
 400          *   code for list of supported stuff
 401          * @param array $join_conds Associative array of table join conditions
 402          *   (optional) (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 403          * @return mixed Database result resource (feed to Database::fetchObject
 404          *   or whatever), or false on failure
 405          * @throws DBQueryError
 406          * @throws DBUnexpectedError
 407          * @throws Exception
 408          */
 409         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
 410                 $options = [], $join_conds = []
 411         ) {
 412                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 413                 if ( isset( $options['EXPLAIN'] ) ) {
 414                         try {
 415                                 $this->scrollableCursor = false;
 416                                 $this->prepareStatements = false;
 417                                 $this->query( "SET SHOWPLAN_ALL ON" );
 418                                 $ret = $this->query( $sql, $fname );
 419                                 $this->query( "SET SHOWPLAN_ALL OFF" );
 420                         } catch ( DBQueryError $dqe ) {
 421                                 if ( isset( $options['FOR COUNT'] ) ) {
 422                                         // likely don't have privs for SHOWPLAN, so run a select count instead
 423                                         $this->query( "SET SHOWPLAN_ALL OFF" );
 424                                         unset( $options['EXPLAIN'] );
 425                                         $ret = $this->select(
 426                                                 $table,
 427                                                 'COUNT(*) AS EstimateRows',
 428                                                 $conds,
 429                                                 $fname,
 430                                                 $options,
 431                                                 $join_conds
 432                                         );
 433                                 } else {
 434                                         // someone actually wanted the query plan instead of an est row count
 435                                         // let them know of the error
 436                                         $this->scrollableCursor = true;
 437                                         $this->prepareStatements = true;
 438                                         throw $dqe;
 439                                 }
 440                         }
 441                         $this->scrollableCursor = true;
 442                         $this->prepareStatements = true;
 443                         return $ret;
 444                 }
 445                 return $this->query( $sql, $fname );
 446         }
 447
 448         /**
 449          * SELECT wrapper
 450          *
 451          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 452          * @param mixed $vars Array or string, field name(s) to be retrieved
 453          * @param mixed $conds Array or string, condition(s) for WHERE
 454          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 455          * @param array $options Associative array of options (e.g. [ 'GROUP BY' => 'page_title' ]),
 456          *   see Database::makeSelectOptions code for list of supported stuff
 457          * @param array $join_conds Associative array of table join conditions (optional)
 458          *    (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 459          * @return string The SQL text
 460          */
 461         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
 462                 $options = [], $join_conds = []
 463         ) {
 464                 if ( isset( $options['EXPLAIN'] ) ) {
 465                         unset( $options['EXPLAIN'] );
 466                 }
 467
 468                 $sql = parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 469
 470                 // try to rewrite aggregations of bit columns (currently MAX and MIN)
 471                 if ( strpos( $sql, 'MAX(' ) !== false || strpos( $sql, 'MIN(' ) !== false ) {
 472                         $bitColumns = [];
 473                         if ( is_array( $table ) ) {
 474                                 $tables = $table;
 475                                 while ( $tables ) {
 476                                         $t = array_pop( $tables );
 477                                         if ( is_array( $t ) ) {
 478                                                 $tables = array_merge( $tables, $t );
 479                                         } else {
 480                                                 $bitColumns += $this->getBitColumns( $this->tableName( $t ) );
 481                                         }
 482                                 }
 483                         } else {
 484                                 $bitColumns = $this->getBitColumns( $this->tableName( $table ) );
 485                         }
 486
 487                         foreach ( $bitColumns as $col => $info ) {
 488                                 $replace = [
 489                                         "MAX({$col})" => "MAX(CAST({$col} AS tinyint))",
 490                                         "MIN({$col})" => "MIN(CAST({$col} AS tinyint))",
 491                                 ];
 492                                 $sql = str_replace( array_keys( $replace ), array_values( $replace ), $sql );
 493                         }
 494                 }
 495
 496                 return $sql;
 497         }
 498
 499         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
 500                 $fname = __METHOD__
 501         ) {
 502                 $this->scrollableCursor = false;
 503                 try {
 504                         parent::deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname );
 505                 } catch ( Exception $e ) {
 506                         $this->scrollableCursor = true;
 507                         throw $e;
 508                 }
 509                 $this->scrollableCursor = true;
 510         }
 511
 512         public function delete( $table, $conds, $fname = __METHOD__ ) {
 513                 $this->scrollableCursor = false;
 514                 try {
 515                         parent::delete( $table, $conds, $fname );
 516                 } catch ( Exception $e ) {
 517                         $this->scrollableCursor = true;
 518                         throw $e;
 519                 }
 520                 $this->scrollableCursor = true;
 521         }
 522
 523         /**
 524          * Estimate rows in dataset
 525          * Returns estimated count, based on SHOWPLAN_ALL output
 526          * This is not necessarily an accurate estimate, so use sparingly
 527          * Returns -1 if count cannot be found
 528          * Takes same arguments as Database::select()
 529          * @param string $table
 530          * @param string $var
 531          * @param string $conds
 532          * @param string $fname
 533          * @param array $options
 534          * @param array $join_conds
 535          * @return int
 536          */
 537         public function estimateRowCount( $table, $var = '*', $conds = '',
 538                 $fname = __METHOD__, $options = [], $join_conds = []
 539         ) {
 540                 $conds = $this->normalizeConditions( $conds, $fname );
 541                 $column = $this->extractSingleFieldFromList( $var );
 542                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 543                         $conds[] = "$column IS NOT NULL";
 544                 }
 545
 546                 // http://msdn2.microsoft.com/en-us/library/aa259203.aspx
 547                 $options['EXPLAIN'] = true;
 548                 $options['FOR COUNT'] = true;
 549                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 550
 551                 $rows = -1;
 552                 if ( $res ) {
 553                         $row = $this->fetchRow( $res );
 554
 555                         if ( isset( $row['EstimateRows'] ) ) {
 556                                 $rows = (int)$row['EstimateRows'];
 557                         }
 558                 }
 559
 560                 return $rows;
 561         }
 562
 563         /**
 564          * Returns information about an index
 565          * If errors are explicitly ignored, returns NULL on failure
 566          * @param string $table
 567          * @param string $index
 568          * @param string $fname
 569          * @return array|bool|null
 570          */
 571         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 572                 # This does not return the same info as MYSQL would, but that's OK
 573                 # because MediaWiki never uses the returned value except to check for
 574                 # the existence of indexes.
 575                 $sql = "sp_helpindex '" . $this->tableName( $table ) . "'";
 576                 $res = $this->query( $sql, $fname );
 577
 578                 if ( !$res ) {
 579                         return null;
 580                 }
 581
 582                 $result = [];
 583                 foreach ( $res as $row ) {
 584                         if ( $row->index_name == $index ) {
 585                                 $row->Non_unique = !stristr( $row->index_description, "unique" );
 586                                 $cols = explode( ", ", $row->index_keys );
 587                                 foreach ( $cols as $col ) {
 588                                         $row->Column_name = trim( $col );
 589                                         $result[] = clone $row;
 590                                 }
 591                         } elseif ( $index == 'PRIMARY' && stristr( $row->index_description, 'PRIMARY' ) ) {
 592                                 $row->Non_unique = 0;
 593                                 $cols = explode( ", ", $row->index_keys );
 594                                 foreach ( $cols as $col ) {
 595                                         $row->Column_name = trim( $col );
 596                                         $result[] = clone $row;
 597                                 }
 598                         }
 599                 }
 600
 601                 return $result ?: false;
 602         }
 603
 604         /**
 605          * INSERT wrapper, inserts an array into a table
 606          *
 607          * $arrToInsert may be a single associative array, or an array of these with numeric keys, for
 608          * multi-row insert.
 609          *
 610          * Usually aborts on failure
 611          * If errors are explicitly ignored, returns success
 612          * @param string $table
 613          * @param array $arrToInsert
 614          * @param string $fname
 615          * @param array $options
 616          * @return bool
 617          * @throws Exception
 618          */
 619         public function insert( $table, $arrToInsert, $fname = __METHOD__, $options = [] ) {
 620                 # No rows to insert, easy just return now
 621                 if ( !count( $arrToInsert ) ) {
 622                         return true;
 623                 }
 624
 625                 if ( !is_array( $options ) ) {
 626                         $options = [ $options ];
 627                 }
 628
 629                 $table = $this->tableName( $table );
 630
 631                 if ( !( isset( $arrToInsert[0] ) && is_array( $arrToInsert[0] ) ) ) { // Not multi row
 632                         $arrToInsert = [ 0 => $arrToInsert ]; // make everything multi row compatible
 633                 }
 634
 635                 // We know the table we're inserting into, get its identity column
 636                 $identity = null;
 637                 // strip matching square brackets and the db/schema from table name
 638                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
 639                 $tableRaw = array_pop( $tableRawArr );
 640                 $res = $this->doQuery(
 641                         "SELECT NAME AS idColumn FROM SYS.IDENTITY_COLUMNS " .
 642                                 "WHERE OBJECT_NAME(OBJECT_ID)='{$tableRaw}'"
 643                 );
 644                 if ( $res && sqlsrv_has_rows( $res ) ) {
 645                         // There is an identity for this table.
 646                         $identityArr = sqlsrv_fetch_array( $res, SQLSRV_FETCH_ASSOC );
 647                         $identity = array_pop( $identityArr );
 648                 }
 649                 sqlsrv_free_stmt( $res );
 650
 651                 // Determine binary/varbinary fields so we can encode data as a hex string like 0xABCDEF
 652                 $binaryColumns = $this->getBinaryColumns( $table );
 653
 654                 // INSERT IGNORE is not supported by SQL Server
 655                 // remove IGNORE from options list and set ignore flag to true
 656                 if ( in_array( 'IGNORE', $options ) ) {
 657                         $options = array_diff( $options, [ 'IGNORE' ] );
 658                         $this->ignoreDupKeyErrors = true;
 659                 }
 660
 661                 $ret = null;
 662                 foreach ( $arrToInsert as $a ) {
 663                         // start out with empty identity column, this is so we can return
 664                         // it as a result of the INSERT logic
 665                         $sqlPre = '';
 666                         $sqlPost = '';
 667                         $identityClause = '';
 668
 669                         // if we have an identity column
 670                         if ( $identity ) {
 671                                 // iterate through
 672                                 foreach ( $a as $k => $v ) {
 673                                         if ( $k == $identity ) {
 674                                                 if ( !is_null( $v ) ) {
 675                                                         // there is a value being passed to us,
 676                                                         // we need to turn on and off inserted identity
 677                                                         $sqlPre = "SET IDENTITY_INSERT $table ON;";
 678                                                         $sqlPost = ";SET IDENTITY_INSERT $table OFF;";
 679                                                 } else {
 680                                                         // we can't insert NULL into an identity column,
 681                                                         // so remove the column from the insert.
 682                                                         unset( $a[$k] );
 683                                                 }
 684                                         }
 685                                 }
 686
 687                                 // we want to output an identity column as result
 688                                 $identityClause = "OUTPUT INSERTED.$identity ";
 689                         }
 690
 691                         $keys = array_keys( $a );
 692
 693                         // Build the actual query
 694                         $sql = $sqlPre . 'INSERT ' . implode( ' ', $options ) .
 695                                 " INTO $table (" . implode( ',', $keys ) . ") $identityClause VALUES (";
 696
 697                         $first = true;
 698                         foreach ( $a as $key => $value ) {
 699                                 if ( isset( $binaryColumns[$key] ) ) {
 700                                         $value = new MssqlBlob( $value );
 701                                 }
 702                                 if ( $first ) {
 703                                         $first = false;
 704                                 } else {
 705                                         $sql .= ',';
 706                                 }
 707                                 if ( is_null( $value ) ) {
 708                                         $sql .= 'null';
 709                                 } elseif ( is_array( $value ) || is_object( $value ) ) {
 710                                         if ( is_object( $value ) && $value instanceof Blob ) {
 711                                                 $sql .= $this->addQuotes( $value );
 712                                         } else {
 713                                                 $sql .= $this->addQuotes( serialize( $value ) );
 714                                         }
 715                                 } else {
 716                                         $sql .= $this->addQuotes( $value );
 717                                 }
 718                         }
 719                         $sql .= ')' . $sqlPost;
 720
 721                         // Run the query
 722                         $this->scrollableCursor = false;
 723                         try {
 724                                 $ret = $this->query( $sql );
 725                         } catch ( Exception $e ) {
 726                                 $this->scrollableCursor = true;
 727                                 $this->ignoreDupKeyErrors = false;
 728                                 throw $e;
 729                         }
 730                         $this->scrollableCursor = true;
 731
 732                         if ( $ret instanceof ResultWrapper && !is_null( $identity ) ) {
 733                                 // Then we want to get the identity column value we were assigned and save it off
 734                                 $row = $ret->fetchObject();
 735                                 if ( is_object( $row ) ) {
 736                                         $this->lastInsertId = $row->$identity;
 737                                         // It seems that mAffectedRows is -1 sometimes when OUTPUT INSERTED.identity is
 738                                         // used if we got an identity back, we know for sure a row was affected, so
 739                                         // adjust that here
 740                                         if ( $this->lastAffectedRowCount == -1 ) {
 741                                                 $this->lastAffectedRowCount = 1;
 742                                         }
 743                                 }
 744                         }
 745                 }
 746
 747                 $this->ignoreDupKeyErrors = false;
 748
 749                 return $ret;
 750         }
 751
 752         /**
 753          * INSERT SELECT wrapper
 754          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 755          * Source items may be literals rather than field names, but strings should
 756          * be quoted with Database::addQuotes().
 757          * @param string $destTable
 758          * @param array|string $srcTable May be an array of tables.
 759          * @param array $varMap
 760          * @param array $conds May be "*" to copy the whole table.
 761          * @param string $fname
 762          * @param array $insertOptions
 763          * @param array $selectOptions
 764          * @param array $selectJoinConds
 765          * @return bool
 766          * @throws Exception
 767          */
 768         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 769                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
 770         ) {
 771                 $this->scrollableCursor = false;
 772                 try {
 773                         $ret = parent::nativeInsertSelect(
 774                                 $destTable,
 775                                 $srcTable,
 776                                 $varMap,
 777                                 $conds,
 778                                 $fname,
 779                                 $insertOptions,
 780                                 $selectOptions,
 781                                 $selectJoinConds
 782                         );
 783                 } catch ( Exception $e ) {
 784                         $this->scrollableCursor = true;
 785                         throw $e;
 786                 }
 787                 $this->scrollableCursor = true;
 788
 789                 return $ret;
 790         }
 791
 792         /**
 793          * UPDATE wrapper. Takes a condition array and a SET array.
 794          *
 795          * @param string $table Name of the table to UPDATE. This will be passed through
 796          *                Database::tableName().
 797          *
 798          * @param array $values An array of values to SET. For each array element,
 799          *                the key gives the field name, and the value gives the data
 800          *                to set that field to. The data will be quoted by
 801          *                Database::addQuotes().
 802          *
 803          * @param array $conds An array of conditions (WHERE). See
 804          *                Database::select() for the details of the format of
 805          *                condition arrays. Use '*' to update all rows.
 806          *
 807          * @param string $fname The function name of the caller (from __METHOD__),
 808          *                for logging and profiling.
 809          *
 810          * @param array $options An array of UPDATE options, can be:
 811          *                   - IGNORE: Ignore unique key conflicts
 812          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
 813          * @return bool
 814          * @throws DBUnexpectedError
 815          * @throws Exception
 816          */
 817         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
 818                 $table = $this->tableName( $table );
 819                 $binaryColumns = $this->getBinaryColumns( $table );
 820
 821                 $opts = $this->makeUpdateOptions( $options );
 822                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET, $binaryColumns );
 823
 824                 if ( $conds !== [] && $conds !== '*' ) {
 825                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND, $binaryColumns );
 826                 }
 827
 828                 $this->scrollableCursor = false;
 829                 try {
 830                         $this->query( $sql );
 831                 } catch ( Exception $e ) {
 832                         $this->scrollableCursor = true;
 833                         throw $e;
 834                 }
 835                 $this->scrollableCursor = true;
 836                 return true;
 837         }
 838
 839         /**
 840          * Makes an encoded list of strings from an array
 841          * @param array $a Containing the data
 842          * @param int $mode Constant
 843          *      - LIST_COMMA:          comma separated, no field names
 844          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
 845          *        the documentation for $conds in Database::select().
 846          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
 847          *      - LIST_SET:            comma separated with field names, like a SET clause
 848          *      - LIST_NAMES:          comma separated field names
 849          * @param array $binaryColumns Contains a list of column names that are binary types
 850          *      This is a custom parameter only present for MS SQL.
 851          *
 852          * @throws DBUnexpectedError
 853          * @return string
 854          */
 855         public function makeList( $a, $mode = LIST_COMMA, $binaryColumns = [] ) {
 856                 if ( !is_array( $a ) ) {
 857                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
 858                 }
 859
 860                 if ( $mode != LIST_NAMES ) {
 861                         // In MS SQL, values need to be specially encoded when they are
 862                         // inserted into binary fields. Perform this necessary encoding
 863                         // for the specified set of columns.
 864                         foreach ( array_keys( $a ) as $field ) {
 865                                 if ( !isset( $binaryColumns[$field] ) ) {
 866                                         continue;
 867                                 }
 868
 869                                 if ( is_array( $a[$field] ) ) {
 870                                         foreach ( $a[$field] as &$v ) {
 871                                                 $v = new MssqlBlob( $v );
 872                                         }
 873                                         unset( $v );
 874                                 } else {
 875                                         $a[$field] = new MssqlBlob( $a[$field] );
 876                                 }
 877                         }
 878                 }
 879
 880                 return parent::makeList( $a, $mode );
 881         }
 882
 883         /**
 884          * @param string $table
 885          * @param string $field
 886          * @return int Returns the size of a text field, or -1 for "unlimited"
 887          */
 888         public function textFieldSize( $table, $field ) {
 889                 $table = $this->tableName( $table );
 890                 $sql = "SELECT CHARACTER_MAXIMUM_LENGTH,DATA_TYPE FROM INFORMATION_SCHEMA.Columns
 891                         WHERE TABLE_NAME = '$table' AND COLUMN_NAME = '$field'";
 892                 $res = $this->query( $sql );
 893                 $row = $this->fetchRow( $res );
 894                 $size = -1;
 895                 if ( strtolower( $row['DATA_TYPE'] ) != 'text' ) {
 896                         $size = $row['CHARACTER_MAXIMUM_LENGTH'];
 897                 }
 898
 899                 return $size;
 900         }
 901
 902         /**
 903          * Construct a LIMIT query with optional offset
 904          * This is used for query pages
 905          *
 906          * @param string $sql SQL query we will append the limit too
 907          * @param int $limit The SQL limit
 908          * @param bool|int $offset The SQL offset (default false)
 909          * @return array|string
 910          * @throws DBUnexpectedError
 911          */
 912         public function limitResult( $sql, $limit, $offset = false ) {
 913                 if ( $offset === false || $offset == 0 ) {
 914                         if ( strpos( $sql, "SELECT" ) === false ) {
 915                                 return "TOP {$limit} " . $sql;
 916                         } else {
 917                                 return preg_replace( '/\bSELECT(\s+DISTINCT)?\b/Dsi',
 918                                         'SELECT$1 TOP ' . $limit, $sql, 1 );
 919                         }
 920                 } else {
 921                         // This one is fun, we need to pull out the select list as well as any ORDER BY clause
 922                         $select = $orderby = [];
 923                         $s1 = preg_match( '#SELECT\s+(.+?)\s+FROM#Dis', $sql, $select );
 924                         $s2 = preg_match( '#(ORDER BY\s+.+?)(\s*FOR XML .*)?$#Dis', $sql, $orderby );
 925                         $postOrder = '';
 926                         $first = $offset + 1;
 927                         $last = $offset + $limit;
 928                         $sub1 = 'sub_' . $this->subqueryId;
 929                         $sub2 = 'sub_' . ( $this->subqueryId + 1 );
 930                         $this->subqueryId += 2;
 931                         if ( !$s1 ) {
 932                                 // wat
 933                                 throw new DBUnexpectedError( $this, "Attempting to LIMIT a non-SELECT query\n" );
 934                         }
 935                         if ( !$s2 ) {
 936                                 // no ORDER BY
 937                                 $overOrder = 'ORDER BY (SELECT 1)';
 938                         } else {
 939                                 if ( !isset( $orderby[2] ) || !$orderby[2] ) {
 940                                         // don't need to strip it out if we're using a FOR XML clause
 941                                         $sql = str_replace( $orderby[1], '', $sql );
 942                                 }
 943                                 $overOrder = $orderby[1];
 944                                 $postOrder = ' ' . $overOrder;
 945                         }
 946                         $sql = "SELECT {$select[1]}
 947                                         FROM (
 948                                                 SELECT ROW_NUMBER() OVER({$overOrder}) AS rowNumber, *
 949                                                 FROM ({$sql}) {$sub1}
 950                                         ) {$sub2}
 951                                         WHERE rowNumber BETWEEN {$first} AND {$last}{$postOrder}";
 952
 953                         return $sql;
 954                 }
 955         }
 956
 957         /**
 958          * If there is a limit clause, parse it, strip it, and pass the remaining
 959          * SQL through limitResult() with the appropriate parameters. Not the
 960          * prettiest solution, but better than building a whole new parser. This
 961          * exists becase there are still too many extensions that don't use dynamic
 962          * sql generation.
 963          *
 964          * @param string $sql
 965          * @return array|mixed|string
 966          */
 967         public function LimitToTopN( $sql ) {
 968                 // Matches: LIMIT {[offset,] row_count | row_count OFFSET offset}
 969                 $pattern = '/\bLIMIT\s+((([0-9]+)\s*,\s*)?([0-9]+)(\s+OFFSET\s+([0-9]+))?)/i';
 970                 if ( preg_match( $pattern, $sql, $matches ) ) {
 971                         $row_count = $matches[4];
 972                         $offset = $matches[3] ?: $matches[6] ?: false;
 973
 974                         // strip the matching LIMIT clause out
 975                         $sql = str_replace( $matches[0], '', $sql );
 976
 977                         return $this->limitResult( $sql, $row_count, $offset );
 978                 }
 979
 980                 return $sql;
 981         }
 982
 983         /**
 984          * @return string Wikitext of a link to the server software's web site
 985          */
 986         public function getSoftwareLink() {
 987                 return "[{{int:version-db-mssql-url}} MS SQL Server]";
 988         }
 989
 990         /**
 991          * @return string Version information from the database
 992          */
 993         public function getServerVersion() {
 994                 $server_info = sqlsrv_server_info( $this->conn );
 995                 $version = 'Error';
 996                 if ( isset( $server_info['SQLServerVersion'] ) ) {
 997                         $version = $server_info['SQLServerVersion'];
 998                 }
 999
1000                 return $version;
1001         }
1002
1003         /**
1004          * @param string $table
1005          * @param string $fname
1006          * @return bool
1007          */
1008         public function tableExists( $table, $fname = __METHOD__ ) {
1009                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
1010
1011                 if ( $db !== false ) {
1012                         // remote database
1013                         $this->queryLogger->error( "Attempting to call tableExists on a remote table" );
1014                         return false;
1015                 }
1016
1017                 if ( $schema === false ) {
1018                         $schema = $this->schema;
1019                 }
1020
1021                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.TABLES
1022                         WHERE TABLE_TYPE = 'BASE TABLE'
1023                         AND TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table'" );
1024
1025                 if ( $res->numRows() ) {
1026                         return true;
1027                 } else {
1028                         return false;
1029                 }
1030         }
1031
1032         /**
1033          * Query whether a given column exists in the mediawiki schema
1034          * @param string $table
1035          * @param string $field
1036          * @param string $fname
1037          * @return bool
1038          */
1039         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1040                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
1041
1042                 if ( $db !== false ) {
1043                         // remote database
1044                         $this->queryLogger->error( "Attempting to call fieldExists on a remote table" );
1045                         return false;
1046                 }
1047
1048                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS
1049                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1050
1051                 if ( $res->numRows() ) {
1052                         return true;
1053                 } else {
1054                         return false;
1055                 }
1056         }
1057
1058         public function fieldInfo( $table, $field ) {
1059                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
1060
1061                 if ( $db !== false ) {
1062                         // remote database
1063                         $this->queryLogger->error( "Attempting to call fieldInfo on a remote table" );
1064                         return false;
1065                 }
1066
1067                 $res = $this->query( "SELECT * FROM INFORMATION_SCHEMA.COLUMNS
1068                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1069
1070                 $meta = $res->fetchRow();
1071                 if ( $meta ) {
1072                         return new MssqlField( $meta );
1073                 }
1074
1075                 return false;
1076         }
1077
1078         protected function doSavepoint( $identifier, $fname ) {
1079                 $this->query( 'SAVE TRANSACTION ' . $this->addIdentifierQuotes( $identifier ), $fname );
1080         }
1081
1082         protected function doReleaseSavepoint( $identifier, $fname ) {
1083                 // Not supported. Also not really needed, a new doSavepoint() for the
1084                 // same identifier will overwrite the old.
1085         }
1086
1087         protected function doRollbackToSavepoint( $identifier, $fname ) {
1088                 $this->query( 'ROLLBACK TRANSACTION ' . $this->addIdentifierQuotes( $identifier ), $fname );
1089         }
1090
1091         /**
1092          * Begin a transaction, committing any previously open transaction
1093          * @param string $fname
1094          */
1095         protected function doBegin( $fname = __METHOD__ ) {
1096                 sqlsrv_begin_transaction( $this->conn );
1097                 $this->trxLevel = 1;
1098         }
1099
1100         /**
1101          * End a transaction
1102          * @param string $fname
1103          */
1104         protected function doCommit( $fname = __METHOD__ ) {
1105                 sqlsrv_commit( $this->conn );
1106                 $this->trxLevel = 0;
1107         }
1108
1109         /**
1110          * Rollback a transaction.
1111          * No-op on non-transactional databases.
1112          * @param string $fname
1113          */
1114         protected function doRollback( $fname = __METHOD__ ) {
1115                 sqlsrv_rollback( $this->conn );
1116                 $this->trxLevel = 0;
1117         }
1118
1119         /**
1120          * @param string $s
1121          * @return string
1122          */
1123         public function strencode( $s ) {
1124                 // Should not be called by us
1125                 return str_replace( "'", "''", $s );
1126         }
1127
1128         /**
1129          * @param string|int|null|bool|Blob $s
1130          * @return string|int
1131          */
1132         public function addQuotes( $s ) {
1133                 if ( $s instanceof MssqlBlob ) {
1134                         return $s->fetch();
1135                 } elseif ( $s instanceof Blob ) {
1136                         // this shouldn't really ever be called, but it's here if needed
1137                         // (and will quite possibly make the SQL error out)
1138                         $blob = new MssqlBlob( $s->fetch() );
1139                         return $blob->fetch();
1140                 } else {
1141                         if ( is_bool( $s ) ) {
1142                                 $s = $s ? 1 : 0;
1143                         }
1144                         return parent::addQuotes( $s );
1145                 }
1146         }
1147
1148         /**
1149          * @param string $s
1150          * @return string
1151          */
1152         public function addIdentifierQuotes( $s ) {
1153                 // http://msdn.microsoft.com/en-us/library/aa223962.aspx
1154                 return '[' . $s . ']';
1155         }
1156
1157         /**
1158          * @param string $name
1159          * @return bool
1160          */
1161         public function isQuotedIdentifier( $name ) {
1162                 return strlen( $name ) && $name[0] == '[' && substr( $name, -1, 1 ) == ']';
1163         }
1164
1165         /**
1166          * MS SQL supports more pattern operators than other databases (ex: [,],^)
1167          *
1168          * @param string $s
1169          * @param string $escapeChar
1170          * @return string
1171          */
1172         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
1173                 return str_replace( [ $escapeChar, '%', '_', '[', ']', '^' ],
1174                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_",
1175                                 "{$escapeChar}[", "{$escapeChar}]", "{$escapeChar}^" ],
1176                         $s );
1177         }
1178
1179         /**
1180          * @param string $db
1181          * @return bool
1182          */
1183         public function selectDB( $db ) {
1184                 try {
1185                         $this->dbName = $db;
1186                         $this->query( "USE $db" );
1187                         return true;
1188                 } catch ( Exception $e ) {
1189                         return false;
1190                 }
1191         }
1192
1193         /**
1194          * @param array $options An associative array of options to be turned into
1195          *   an SQL query, valid keys are listed in the function.
1196          * @return array
1197          */
1198         public function makeSelectOptions( $options ) {
1199                 $tailOpts = '';
1200                 $startOpts = '';
1201
1202                 $noKeyOptions = [];
1203                 foreach ( $options as $key => $option ) {
1204                         if ( is_numeric( $key ) ) {
1205                                 $noKeyOptions[$option] = true;
1206                         }
1207                 }
1208
1209                 $tailOpts .= $this->makeGroupByWithHaving( $options );
1210
1211                 $tailOpts .= $this->makeOrderBy( $options );
1212
1213                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1214                         $startOpts .= 'DISTINCT';
1215                 }
1216
1217                 if ( isset( $noKeyOptions['FOR XML'] ) ) {
1218                         // used in group concat field emulation
1219                         $tailOpts .= " FOR XML PATH('')";
1220                 }
1221
1222                 // we want this to be compatible with the output of parent::makeSelectOptions()
1223                 return [ $startOpts, '', $tailOpts, '', '' ];
1224         }
1225
1226         public function getType() {
1227                 return 'mssql';
1228         }
1229
1230         /**
1231          * @param array $stringList
1232          * @return string
1233          */
1234         public function buildConcat( $stringList ) {
1235                 return implode( ' + ', $stringList );
1236         }
1237
1238         /**
1239          * Build a GROUP_CONCAT or equivalent statement for a query.
1240          * MS SQL doesn't have GROUP_CONCAT so we emulate it with other stuff (and boy is it nasty)
1241          *
1242          * This is useful for combining a field for several rows into a single string.
1243          * NULL values will not appear in the output, duplicated values will appear,
1244          * and the resulting delimiter-separated values have no defined sort order.
1245          * Code using the results may need to use the PHP unique() or sort() methods.
1246          *
1247          * @param string $delim Glue to bind the results together
1248          * @param string|array $table Table name
1249          * @param string $field Field name
1250          * @param string|array $conds Conditions
1251          * @param string|array $join_conds Join conditions
1252          * @return string SQL text
1253          * @since 1.23
1254          */
1255         public function buildGroupConcatField( $delim, $table, $field, $conds = '',
1256                 $join_conds = []
1257         ) {
1258                 $gcsq = 'gcsq_' . $this->subqueryId;
1259                 $this->subqueryId++;
1260
1261                 $delimLen = strlen( $delim );
1262                 $fld = "{$field} + {$this->addQuotes( $delim )}";
1263                 $sql = "(SELECT LEFT({$field}, LEN({$field}) - {$delimLen}) FROM ("
1264                         . $this->selectSQLText( $table, $fld, $conds, null, [ 'FOR XML' ], $join_conds )
1265                         . ") {$gcsq} ({$field}))";
1266
1267                 return $sql;
1268         }
1269
1270         public function buildSubstring( $input, $startPosition, $length = null ) {
1271                 $this->assertBuildSubstringParams( $startPosition, $length );
1272                 if ( $length === null ) {
1273                         /**
1274                          * MSSQL doesn't allow an empty length parameter, so when we don't want to limit the
1275                          * length returned use the default maximum size of text.
1276                          * @see https://docs.microsoft.com/en-us/sql/t-sql/statements/set-textsize-transact-sql
1277                          */
1278                         $length = 2147483647;
1279                 }
1280                 return 'SUBSTRING(' . implode( ',', [ $input, $startPosition, $length ] ) . ')';
1281         }
1282
1283         /**
1284          * Returns an associative array for fields that are of type varbinary, binary, or image
1285          * $table can be either a raw table name or passed through tableName() first
1286          * @param string $table
1287          * @return array
1288          */
1289         private function getBinaryColumns( $table ) {
1290                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1291                 $tableRaw = array_pop( $tableRawArr );
1292
1293                 if ( $this->binaryColumnCache === null ) {
1294                         $this->populateColumnCaches();
1295                 }
1296
1297                 return isset( $this->binaryColumnCache[$tableRaw] )
1298                         ? $this->binaryColumnCache[$tableRaw]
1299                         : [];
1300         }
1301
1302         /**
1303          * @param string $table
1304          * @return array
1305          */
1306         private function getBitColumns( $table ) {
1307                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1308                 $tableRaw = array_pop( $tableRawArr );
1309
1310                 if ( $this->bitColumnCache === null ) {
1311                         $this->populateColumnCaches();
1312                 }
1313
1314                 return isset( $this->bitColumnCache[$tableRaw] )
1315                         ? $this->bitColumnCache[$tableRaw]
1316                         : [];
1317         }
1318
1319         private function populateColumnCaches() {
1320                 $res = $this->select( 'INFORMATION_SCHEMA.COLUMNS', '*',
1321                         [
1322                                 'TABLE_CATALOG' => $this->dbName,
1323                                 'TABLE_SCHEMA' => $this->schema,
1324                                 'DATA_TYPE' => [ 'varbinary', 'binary', 'image', 'bit' ]
1325                         ] );
1326
1327                 $this->binaryColumnCache = [];
1328                 $this->bitColumnCache = [];
1329                 foreach ( $res as $row ) {
1330                         if ( $row->DATA_TYPE == 'bit' ) {
1331                                 $this->bitColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1332                         } else {
1333                                 $this->binaryColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1334                         }
1335                 }
1336         }
1337
1338         /**
1339          * @param string $name
1340          * @param string $format
1341          * @return string
1342          */
1343         function tableName( $name, $format = 'quoted' ) {
1344                 # Replace reserved words with better ones
1345                 switch ( $name ) {
1346                         case 'user':
1347                                 return $this->realTableName( 'mwuser', $format );
1348                         default:
1349                                 return $this->realTableName( $name, $format );
1350                 }
1351         }
1352
1353         /**
1354          * call this instead of tableName() in the updater when renaming tables
1355          * @param string $name
1356          * @param string $format One of quoted, raw, or split
1357          * @return string
1358          */
1359         function realTableName( $name, $format = 'quoted' ) {
1360                 $table = parent::tableName( $name, $format );
1361                 if ( $format == 'split' ) {
1362                         // Used internally, we want the schema split off from the table name and returned
1363                         // as a list with 3 elements (database, schema, table)
1364                         $table = explode( '.', $table );
1365                         while ( count( $table ) < 3 ) {
1366                                 array_unshift( $table, false );
1367                         }
1368                 }
1369                 return $table;
1370         }
1371
1372         /**
1373          * Delete a table
1374          * @param string $tableName
1375          * @param string $fName
1376          * @return bool|ResultWrapper
1377          * @since 1.18
1378          */
1379         public function dropTable( $tableName, $fName = __METHOD__ ) {
1380                 if ( !$this->tableExists( $tableName, $fName ) ) {
1381                         return false;
1382                 }
1383
1384                 // parent function incorrectly appends CASCADE, which we don't want
1385                 $sql = "DROP TABLE " . $this->tableName( $tableName );
1386
1387                 return $this->query( $sql, $fName );
1388         }
1389
1390         /**
1391          * Called in the installer and updater.
1392          * Probably doesn't need to be called anywhere else in the codebase.
1393          * @param bool|null $value
1394          * @return bool|null
1395          */
1396         public function prepareStatements( $value = null ) {
1397                 $old = $this->prepareStatements;
1398                 if ( $value !== null ) {
1399                         $this->prepareStatements = $value;
1400                 }
1401
1402                 return $old;
1403         }
1404
1405         /**
1406          * Called in the installer and updater.
1407          * Probably doesn't need to be called anywhere else in the codebase.
1408          * @param bool|null $value
1409          * @return bool|null
1410          */
1411         public function scrollableCursor( $value = null ) {
1412                 $old = $this->scrollableCursor;
1413                 if ( $value !== null ) {
1414                         $this->scrollableCursor = $value;
1415                 }
1416
1417                 return $old;
1418         }
1419 }
1420
1421 /**
1422  * @deprecated since 1.29
1423  */
1424 class_alias( DatabaseMssql::class, 'DatabaseMssql' );