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