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