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 implicitGroupby() {
  63                 return false;
  64         }
  65
  66         public function implicitOrderby() {
  67                 return false;
  68         }
  69
  70         public function unionSupportsOrderAndLimit() {
  71                 return false;
  72         }
  73
  74         public function __construct( array $params ) {
  75                 $this->serverPort = $params['port'];
  76                 $this->useWindowsAuth = $params['UseWindowsAuth'];
  77
  78                 parent::__construct( $params );
  79         }
  80
  81         protected function open( $server, $user, $password, $dbName, $schema, $tablePrefix ) {
  82                 // Test for driver support, to avoid suppressed fatal error
  83                 if ( !function_exists( 'sqlsrv_connect' ) ) {
  84                         throw new DBConnectionError(
  85                                 $this,
  86                                 "Microsoft SQL Server Native (sqlsrv) functions missing.
  87                                 You can download the driver from: http://go.microsoft.com/fwlink/?LinkId=123470\n"
  88                         );
  89                 }
  90
  91                 $this->close();
  92                 $this->server = $server;
  93                 $this->user = $user;
  94                 $this->password = $password;
  95
  96                 $connectionInfo = [];
  97
  98                 if ( $dbName != '' ) {
  99                         $connectionInfo['Database'] = $dbName;
 100                 }
 101
 102                 // Decide which auth scenerio to use
 103                 // if we are using Windows auth, then don't add credentials to $connectionInfo
 104                 if ( !$this->useWindowsAuth ) {
 105                         $connectionInfo['UID'] = $user;
 106                         $connectionInfo['PWD'] = $password;
 107                 }
 108
 109                 AtEase::suppressWarnings();
 110                 $this->conn = sqlsrv_connect( $server, $connectionInfo );
 111                 AtEase::restoreWarnings();
 112
 113                 if ( $this->conn === false ) {
 114                         $error = $this->lastError();
 115                         $this->connLogger->error(
 116                                 "Error connecting to {db_server}: {error}",
 117                                 $this->getLogContext( [ 'method' => __METHOD__, 'error' => $error ] )
 118                         );
 119                         throw new DBConnectionError( $this, $error );
 120                 }
 121
 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          */
 161         protected function doQuery( $sql ) {
 162                 // several extensions seem to think that all databases support limits
 163                 // via LIMIT N after the WHERE clause, but  MSSQL uses SELECT TOP N,
 164                 // so to catch any of those extensions we'll do a quick check for a
 165                 // LIMIT clause and pass $sql through $this->LimitToTopN() which parses
 166                 // the LIMIT clause and passes the result to $this->limitResult();
 167                 if ( preg_match( '/\bLIMIT\s*/i', $sql ) ) {
 168                         // massage LIMIT -> TopN
 169                         $sql = $this->LimitToTopN( $sql );
 170                 }
 171
 172                 // MSSQL doesn't have EXTRACT(epoch FROM XXX)
 173                 if ( preg_match( '#\bEXTRACT\s*?\(\s*?EPOCH\s+FROM\b#i', $sql, $matches ) ) {
 174                         // This is same as UNIX_TIMESTAMP, we need to calc # of seconds from 1970
 175                         $sql = str_replace( $matches[0], "DATEDIFF(s,CONVERT(datetime,'1/1/1970'),", $sql );
 176                 }
 177
 178                 // perform query
 179
 180                 // SQLSRV_CURSOR_STATIC is slower than SQLSRV_CURSOR_CLIENT_BUFFERED (one of the two is
 181                 // needed if we want to be able to seek around the result set), however CLIENT_BUFFERED
 182                 // has a bug in the sqlsrv driver where wchar_t types (such as nvarchar) that are empty
 183                 // strings make php throw a fatal error "Severe error translating Unicode"
 184                 if ( $this->scrollableCursor ) {
 185                         $scrollArr = [ 'Scrollable' => SQLSRV_CURSOR_STATIC ];
 186                 } else {
 187                         $scrollArr = [];
 188                 }
 189
 190                 if ( $this->prepareStatements ) {
 191                         // we do prepare + execute so we can get its field metadata for later usage if desired
 192                         $stmt = sqlsrv_prepare( $this->conn, $sql, [], $scrollArr );
 193                         $success = sqlsrv_execute( $stmt );
 194                 } else {
 195                         $stmt = sqlsrv_query( $this->conn, $sql, [], $scrollArr );
 196                         $success = (bool)$stmt;
 197                 }
 198
 199                 // Make a copy to ensure what we add below does not get reflected in future queries
 200                 $ignoreErrors = $this->ignoreErrors;
 201
 202                 if ( $this->ignoreDupKeyErrors ) {
 203                         // ignore duplicate key errors
 204                         // this emulates INSERT IGNORE in MySQL
 205                         $ignoreErrors[] = '2601'; // duplicate key error caused by unique index
 206                         $ignoreErrors[] = '2627'; // duplicate key error caused by primary key
 207                         $ignoreErrors[] = '3621'; // generic "the statement has been terminated" error
 208                 }
 209
 210                 if ( $success === false ) {
 211                         $errors = sqlsrv_errors();
 212                         $success = true;
 213
 214                         foreach ( $errors as $err ) {
 215                                 if ( !in_array( $err['code'], $ignoreErrors ) ) {
 216                                         $success = false;
 217                                         break;
 218                                 }
 219                         }
 220
 221                         if ( $success === false ) {
 222                                 return false;
 223                         }
 224                 }
 225                 // remember number of rows affected
 226                 $this->lastAffectedRowCount = sqlsrv_rows_affected( $stmt );
 227
 228                 return $stmt;
 229         }
 230
 231         public function freeResult( $res ) {
 232                 if ( $res instanceof ResultWrapper ) {
 233                         $res = $res->result;
 234                 }
 235
 236                 sqlsrv_free_stmt( $res );
 237         }
 238
 239         /**
 240          * @param IResultWrapper $res
 241          * @return stdClass
 242          */
 243         public function fetchObject( $res ) {
 244                 // $res is expected to be an instance of MssqlResultWrapper here
 245                 return $res->fetchObject();
 246         }
 247
 248         /**
 249          * @param IResultWrapper $res
 250          * @return array
 251          */
 252         public function fetchRow( $res ) {
 253                 return $res->fetchRow();
 254         }
 255
 256         /**
 257          * @param mixed $res
 258          * @return int
 259          */
 260         public function numRows( $res ) {
 261                 if ( $res instanceof ResultWrapper ) {
 262                         $res = $res->result;
 263                 }
 264
 265                 $ret = sqlsrv_num_rows( $res );
 266
 267                 if ( $ret === false ) {
 268                         // we cannot get an amount of rows from this cursor type
 269                         // has_rows returns bool true/false if the result has rows
 270                         $ret = (int)sqlsrv_has_rows( $res );
 271                 }
 272
 273                 return $ret;
 274         }
 275
 276         /**
 277          * @param mixed $res
 278          * @return int
 279          */
 280         public function numFields( $res ) {
 281                 if ( $res instanceof ResultWrapper ) {
 282                         $res = $res->result;
 283                 }
 284
 285                 return sqlsrv_num_fields( $res );
 286         }
 287
 288         /**
 289          * @param mixed $res
 290          * @param int $n
 291          * @return int
 292          */
 293         public function fieldName( $res, $n ) {
 294                 if ( $res instanceof ResultWrapper ) {
 295                         $res = $res->result;
 296                 }
 297
 298                 return sqlsrv_field_metadata( $res )[$n]['Name'];
 299         }
 300
 301         /**
 302          * This must be called after nextSequenceVal
 303          * @return int|null
 304          */
 305         public function insertId() {
 306                 return $this->lastInsertId;
 307         }
 308
 309         /**
 310          * @param MssqlResultWrapper $res
 311          * @param int $row
 312          * @return bool
 313          */
 314         public function dataSeek( $res, $row ) {
 315                 return $res->seek( $row );
 316         }
 317
 318         /**
 319          * @return string
 320          */
 321         public function lastError() {
 322                 $strRet = '';
 323                 $retErrors = sqlsrv_errors( SQLSRV_ERR_ALL );
 324                 if ( $retErrors != null ) {
 325                         foreach ( $retErrors as $arrError ) {
 326                                 $strRet .= $this->formatError( $arrError ) . "\n";
 327                         }
 328                 } else {
 329                         $strRet = "No errors found";
 330                 }
 331
 332                 return $strRet;
 333         }
 334
 335         /**
 336          * @param array $err
 337          * @return string
 338          */
 339         private function formatError( $err ) {
 340                 return '[SQLSTATE ' .
 341                         $err['SQLSTATE'] . '][Error Code ' . $err['code'] . ']' . $err['message'];
 342         }
 343
 344         /**
 345          * @return string|int
 346          */
 347         public function lastErrno() {
 348                 $err = sqlsrv_errors( SQLSRV_ERR_ALL );
 349                 if ( $err !== null && isset( $err[0] ) ) {
 350                         return $err[0]['code'];
 351                 } else {
 352                         return 0;
 353                 }
 354         }
 355
 356         protected function wasKnownStatementRollbackError() {
 357                 $errors = sqlsrv_errors( SQLSRV_ERR_ALL );
 358                 if ( !$errors ) {
 359                         return false;
 360                 }
 361                 // The transaction vs statement rollback behavior depends on XACT_ABORT, so make sure
 362                 // that the "statement has been terminated" error (3621) is specifically present.
 363                 // https://docs.microsoft.com/en-us/sql/t-sql/statements/set-xact-abort-transact-sql
 364                 $statementOnly = false;
 365                 $codeWhitelist = [ '2601', '2627', '547' ];
 366                 foreach ( $errors as $error ) {
 367                         if ( $error['code'] == '3621' ) {
 368                                 $statementOnly = true;
 369                         } elseif ( !in_array( $error['code'], $codeWhitelist ) ) {
 370                                 $statementOnly = false;
 371                                 break;
 372                         }
 373                 }
 374
 375                 return $statementOnly;
 376         }
 377
 378         public function serverIsReadOnly() {
 379                 $encDatabase = $this->addQuotes( $this->getDBname() );
 380                 $res = $this->query(
 381                         "SELECT IS_READ_ONLY FROM SYS.DATABASES WHERE NAME = $encDatabase",
 382                         __METHOD__
 383                 );
 384                 $row = $this->fetchObject( $res );
 385
 386                 return $row ? (bool)$row->IS_READ_ONLY : false;
 387         }
 388
 389         /**
 390          * @return int
 391          */
 392         protected function fetchAffectedRowCount() {
 393                 return $this->lastAffectedRowCount;
 394         }
 395
 396         /**
 397          * SELECT wrapper
 398          *
 399          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 400          * @param mixed $vars Array or string, field name(s) to be retrieved
 401          * @param mixed $conds Array or string, condition(s) for WHERE
 402          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 403          * @param array $options Associative array of options (e.g.
 404          *   [ 'GROUP BY' => 'page_title' ]), see Database::makeSelectOptions
 405          *   code for list of supported stuff
 406          * @param array $join_conds Associative array of table join conditions
 407          *   (optional) (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 408          * @return mixed Database result resource (feed to Database::fetchObject
 409          *   or whatever), or false on failure
 410          * @throws DBQueryError
 411          * @throws DBUnexpectedError
 412          * @throws Exception
 413          */
 414         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
 415                 $options = [], $join_conds = []
 416         ) {
 417                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 418                 if ( isset( $options['EXPLAIN'] ) ) {
 419                         try {
 420                                 $this->scrollableCursor = false;
 421                                 $this->prepareStatements = false;
 422                                 $this->query( "SET SHOWPLAN_ALL ON" );
 423                                 $ret = $this->query( $sql, $fname );
 424                                 $this->query( "SET SHOWPLAN_ALL OFF" );
 425                         } catch ( DBQueryError $dqe ) {
 426                                 if ( isset( $options['FOR COUNT'] ) ) {
 427                                         // likely don't have privs for SHOWPLAN, so run a select count instead
 428                                         $this->query( "SET SHOWPLAN_ALL OFF" );
 429                                         unset( $options['EXPLAIN'] );
 430                                         $ret = $this->select(
 431                                                 $table,
 432                                                 'COUNT(*) AS EstimateRows',
 433                                                 $conds,
 434                                                 $fname,
 435                                                 $options,
 436                                                 $join_conds
 437                                         );
 438                                 } else {
 439                                         // someone actually wanted the query plan instead of an est row count
 440                                         // let them know of the error
 441                                         $this->scrollableCursor = true;
 442                                         $this->prepareStatements = true;
 443                                         throw $dqe;
 444                                 }
 445                         }
 446                         $this->scrollableCursor = true;
 447                         $this->prepareStatements = true;
 448                         return $ret;
 449                 }
 450                 return $this->query( $sql, $fname );
 451         }
 452
 453         /**
 454          * SELECT wrapper
 455          *
 456          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 457          * @param mixed $vars Array or string, field name(s) to be retrieved
 458          * @param mixed $conds Array or string, condition(s) for WHERE
 459          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 460          * @param array $options Associative array of options (e.g. [ 'GROUP BY' => 'page_title' ]),
 461          *   see Database::makeSelectOptions code for list of supported stuff
 462          * @param array $join_conds Associative array of table join conditions (optional)
 463          *    (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 464          * @return string The SQL text
 465          */
 466         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
 467                 $options = [], $join_conds = []
 468         ) {
 469                 if ( isset( $options['EXPLAIN'] ) ) {
 470                         unset( $options['EXPLAIN'] );
 471                 }
 472
 473                 $sql = parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 474
 475                 // try to rewrite aggregations of bit columns (currently MAX and MIN)
 476                 if ( strpos( $sql, 'MAX(' ) !== false || strpos( $sql, 'MIN(' ) !== false ) {
 477                         $bitColumns = [];
 478                         if ( is_array( $table ) ) {
 479                                 $tables = $table;
 480                                 while ( $tables ) {
 481                                         $t = array_pop( $tables );
 482                                         if ( is_array( $t ) ) {
 483                                                 $tables = array_merge( $tables, $t );
 484                                         } else {
 485                                                 $bitColumns += $this->getBitColumns( $this->tableName( $t ) );
 486                                         }
 487                                 }
 488                         } else {
 489                                 $bitColumns = $this->getBitColumns( $this->tableName( $table ) );
 490                         }
 491
 492                         foreach ( $bitColumns as $col => $info ) {
 493                                 $replace = [
 494                                         "MAX({$col})" => "MAX(CAST({$col} AS tinyint))",
 495                                         "MIN({$col})" => "MIN(CAST({$col} AS tinyint))",
 496                                 ];
 497                                 $sql = str_replace( array_keys( $replace ), array_values( $replace ), $sql );
 498                         }
 499                 }
 500
 501                 return $sql;
 502         }
 503
 504         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
 505                 $fname = __METHOD__
 506         ) {
 507                 $this->scrollableCursor = false;
 508                 try {
 509                         parent::deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname );
 510                 } catch ( Exception $e ) {
 511                         $this->scrollableCursor = true;
 512                         throw $e;
 513                 }
 514                 $this->scrollableCursor = true;
 515         }
 516
 517         public function delete( $table, $conds, $fname = __METHOD__ ) {
 518                 $this->scrollableCursor = false;
 519                 try {
 520                         parent::delete( $table, $conds, $fname );
 521                 } catch ( Exception $e ) {
 522                         $this->scrollableCursor = true;
 523                         throw $e;
 524                 }
 525                 $this->scrollableCursor = true;
 526
 527                 return true;
 528         }
 529
 530         /**
 531          * Estimate rows in dataset
 532          * Returns estimated count, based on SHOWPLAN_ALL output
 533          * This is not necessarily an accurate estimate, so use sparingly
 534          * Returns -1 if count cannot be found
 535          * Takes same arguments as Database::select()
 536          * @param string $table
 537          * @param string $var
 538          * @param string $conds
 539          * @param string $fname
 540          * @param array $options
 541          * @param array $join_conds
 542          * @return int
 543          */
 544         public function estimateRowCount( $table, $var = '*', $conds = '',
 545                 $fname = __METHOD__, $options = [], $join_conds = []
 546         ) {
 547                 $conds = $this->normalizeConditions( $conds, $fname );
 548                 $column = $this->extractSingleFieldFromList( $var );
 549                 if ( is_string( $column ) && !in_array( $column, [ '*', '1' ] ) ) {
 550                         $conds[] = "$column IS NOT NULL";
 551                 }
 552
 553                 // http://msdn2.microsoft.com/en-us/library/aa259203.aspx
 554                 $options['EXPLAIN'] = true;
 555                 $options['FOR COUNT'] = true;
 556                 $res = $this->select( $table, $var, $conds, $fname, $options, $join_conds );
 557
 558                 $rows = -1;
 559                 if ( $res ) {
 560                         $row = $this->fetchRow( $res );
 561
 562                         if ( isset( $row['EstimateRows'] ) ) {
 563                                 $rows = (int)$row['EstimateRows'];
 564                         }
 565                 }
 566
 567                 return $rows;
 568         }
 569
 570         /**
 571          * Returns information about an index
 572          * If errors are explicitly ignored, returns NULL on failure
 573          * @param string $table
 574          * @param string $index
 575          * @param string $fname
 576          * @return array|bool|null
 577          */
 578         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 579                 # This does not return the same info as MYSQL would, but that's OK
 580                 # because MediaWiki never uses the returned value except to check for
 581                 # the existence of indexes.
 582                 $sql = "sp_helpindex '" . $this->tableName( $table ) . "'";
 583                 $res = $this->query( $sql, $fname );
 584
 585                 if ( !$res ) {
 586                         return null;
 587                 }
 588
 589                 $result = [];
 590                 foreach ( $res as $row ) {
 591                         if ( $row->index_name == $index ) {
 592                                 $row->Non_unique = !stristr( $row->index_description, "unique" );
 593                                 $cols = explode( ", ", $row->index_keys );
 594                                 foreach ( $cols as $col ) {
 595                                         $row->Column_name = trim( $col );
 596                                         $result[] = clone $row;
 597                                 }
 598                         } elseif ( $index == 'PRIMARY' && stristr( $row->index_description, 'PRIMARY' ) ) {
 599                                 $row->Non_unique = 0;
 600                                 $cols = explode( ", ", $row->index_keys );
 601                                 foreach ( $cols as $col ) {
 602                                         $row->Column_name = trim( $col );
 603                                         $result[] = clone $row;
 604                                 }
 605                         }
 606                 }
 607
 608                 return $result ?: false;
 609         }
 610
 611         /**
 612          * INSERT wrapper, inserts an array into a table
 613          *
 614          * $arrToInsert may be a single associative array, or an array of these with numeric keys, for
 615          * multi-row insert.
 616          *
 617          * Usually aborts on failure
 618          * If errors are explicitly ignored, returns success
 619          * @param string $table
 620          * @param array $arrToInsert
 621          * @param string $fname
 622          * @param array $options
 623          * @return bool
 624          * @throws Exception
 625          */
 626         public function insert( $table, $arrToInsert, $fname = __METHOD__, $options = [] ) {
 627                 # No rows to insert, easy just return now
 628                 if ( !count( $arrToInsert ) ) {
 629                         return true;
 630                 }
 631
 632                 if ( !is_array( $options ) ) {
 633                         $options = [ $options ];
 634                 }
 635
 636                 $table = $this->tableName( $table );
 637
 638                 if ( !( isset( $arrToInsert[0] ) && is_array( $arrToInsert[0] ) ) ) { // Not multi row
 639                         $arrToInsert = [ 0 => $arrToInsert ]; // make everything multi row compatible
 640                 }
 641
 642                 // We know the table we're inserting into, get its identity column
 643                 $identity = null;
 644                 // strip matching square brackets and the db/schema from table name
 645                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
 646                 $tableRaw = array_pop( $tableRawArr );
 647                 $res = $this->doQuery(
 648                         "SELECT NAME AS idColumn FROM SYS.IDENTITY_COLUMNS " .
 649                                 "WHERE OBJECT_NAME(OBJECT_ID)='{$tableRaw}'"
 650                 );
 651                 if ( $res && sqlsrv_has_rows( $res ) ) {
 652                         // There is an identity for this table.
 653                         $identityArr = sqlsrv_fetch_array( $res, SQLSRV_FETCH_ASSOC );
 654                         $identity = array_pop( $identityArr );
 655                 }
 656                 sqlsrv_free_stmt( $res );
 657
 658                 // Determine binary/varbinary fields so we can encode data as a hex string like 0xABCDEF
 659                 $binaryColumns = $this->getBinaryColumns( $table );
 660
 661                 // INSERT IGNORE is not supported by SQL Server
 662                 // remove IGNORE from options list and set ignore flag to true
 663                 if ( in_array( 'IGNORE', $options ) ) {
 664                         $options = array_diff( $options, [ 'IGNORE' ] );
 665                         $this->ignoreDupKeyErrors = true;
 666                 }
 667
 668                 $ret = null;
 669                 foreach ( $arrToInsert as $a ) {
 670                         // start out with empty identity column, this is so we can return
 671                         // it as a result of the INSERT logic
 672                         $sqlPre = '';
 673                         $sqlPost = '';
 674                         $identityClause = '';
 675
 676                         // if we have an identity column
 677                         if ( $identity ) {
 678                                 // iterate through
 679                                 foreach ( $a as $k => $v ) {
 680                                         if ( $k == $identity ) {
 681                                                 if ( !is_null( $v ) ) {
 682                                                         // there is a value being passed to us,
 683                                                         // we need to turn on and off inserted identity
 684                                                         $sqlPre = "SET IDENTITY_INSERT $table ON;";
 685                                                         $sqlPost = ";SET IDENTITY_INSERT $table OFF;";
 686                                                 } else {
 687                                                         // we can't insert NULL into an identity column,
 688                                                         // so remove the column from the insert.
 689                                                         unset( $a[$k] );
 690                                                 }
 691                                         }
 692                                 }
 693
 694                                 // we want to output an identity column as result
 695                                 $identityClause = "OUTPUT INSERTED.$identity ";
 696                         }
 697
 698                         $keys = array_keys( $a );
 699
 700                         // Build the actual query
 701                         $sql = $sqlPre . 'INSERT ' . implode( ' ', $options ) .
 702                                 " INTO $table (" . implode( ',', $keys ) . ") $identityClause VALUES (";
 703
 704                         $first = true;
 705                         foreach ( $a as $key => $value ) {
 706                                 if ( isset( $binaryColumns[$key] ) ) {
 707                                         $value = new MssqlBlob( $value );
 708                                 }
 709                                 if ( $first ) {
 710                                         $first = false;
 711                                 } else {
 712                                         $sql .= ',';
 713                                 }
 714                                 if ( is_null( $value ) ) {
 715                                         $sql .= 'null';
 716                                 } else {
 717                                         $sql .= $this->addQuotes( $value );
 718                                 }
 719                         }
 720                         $sql .= ')' . $sqlPost;
 721
 722                         // Run the query
 723                         $this->scrollableCursor = false;
 724                         try {
 725                                 $ret = $this->query( $sql );
 726                         } catch ( Exception $e ) {
 727                                 $this->scrollableCursor = true;
 728                                 $this->ignoreDupKeyErrors = false;
 729                                 throw $e;
 730                         }
 731                         $this->scrollableCursor = true;
 732
 733                         if ( $ret instanceof ResultWrapper && !is_null( $identity ) ) {
 734                                 // Then we want to get the identity column value we were assigned and save it off
 735                                 $row = $ret->fetchObject();
 736                                 if ( is_object( $row ) ) {
 737                                         $this->lastInsertId = $row->$identity;
 738                                         // It seems that mAffectedRows is -1 sometimes when OUTPUT INSERTED.identity is
 739                                         // used if we got an identity back, we know for sure a row was affected, so
 740                                         // adjust that here
 741                                         if ( $this->lastAffectedRowCount == -1 ) {
 742                                                 $this->lastAffectedRowCount = 1;
 743                                         }
 744                                 }
 745                         }
 746                 }
 747
 748                 $this->ignoreDupKeyErrors = false;
 749
 750                 return true;
 751         }
 752
 753         /**
 754          * INSERT SELECT wrapper
 755          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 756          * Source items may be literals rather than field names, but strings should
 757          * be quoted with Database::addQuotes().
 758          * @param string $destTable
 759          * @param array|string $srcTable May be an array of tables.
 760          * @param array $varMap
 761          * @param array $conds May be "*" to copy the whole table.
 762          * @param string $fname
 763          * @param array $insertOptions
 764          * @param array $selectOptions
 765          * @param array $selectJoinConds
 766          * @throws Exception
 767          */
 768         protected function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 769                 $insertOptions = [], $selectOptions = [], $selectJoinConds = []
 770         ) {
 771                 $this->scrollableCursor = false;
 772                 try {
 773                         parent::nativeInsertSelect(
 774                                 $destTable,
 775                                 $srcTable,
 776                                 $varMap,
 777                                 $conds,
 778                                 $fname,
 779                                 $insertOptions,
 780                                 $selectOptions,
 781                                 $selectJoinConds
 782                         );
 783                 } catch ( Exception $e ) {
 784                         $this->scrollableCursor = true;
 785                         throw $e;
 786                 }
 787                 $this->scrollableCursor = true;
 788         }
 789
 790         /**
 791          * UPDATE wrapper. Takes a condition array and a SET array.
 792          *
 793          * @param string $table Name of the table to UPDATE. This will be passed through
 794          *                Database::tableName().
 795          *
 796          * @param array $values An array of values to SET. For each array element,
 797          *                the key gives the field name, and the value gives the data
 798          *                to set that field to. The data will be quoted by
 799          *                Database::addQuotes().
 800          *
 801          * @param array $conds An array of conditions (WHERE). See
 802          *                Database::select() for the details of the format of
 803          *                condition arrays. Use '*' to update all rows.
 804          *
 805          * @param string $fname The function name of the caller (from __METHOD__),
 806          *                for logging and profiling.
 807          *
 808          * @param array $options An array of UPDATE options, can be:
 809          *                   - IGNORE: Ignore unique key conflicts
 810          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
 811          * @return bool
 812          * @throws DBUnexpectedError
 813          * @throws Exception
 814          */
 815         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
 816                 $table = $this->tableName( $table );
 817                 $binaryColumns = $this->getBinaryColumns( $table );
 818
 819                 $opts = $this->makeUpdateOptions( $options );
 820                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET, $binaryColumns );
 821
 822                 if ( $conds !== [] && $conds !== '*' ) {
 823                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND, $binaryColumns );
 824                 }
 825
 826                 $this->scrollableCursor = false;
 827                 try {
 828                         $this->query( $sql );
 829                 } catch ( Exception $e ) {
 830                         $this->scrollableCursor = true;
 831                         throw $e;
 832                 }
 833                 $this->scrollableCursor = true;
 834                 return true;
 835         }
 836
 837         /**
 838          * Makes an encoded list of strings from an array
 839          * @param array $a Containing the data
 840          * @param int $mode Constant
 841          *      - LIST_COMMA:          comma separated, no field names
 842          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
 843          *        the documentation for $conds in Database::select().
 844          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
 845          *      - LIST_SET:            comma separated with field names, like a SET clause
 846          *      - LIST_NAMES:          comma separated field names
 847          * @param array $binaryColumns Contains a list of column names that are binary types
 848          *      This is a custom parameter only present for MS SQL.
 849          *
 850          * @throws DBUnexpectedError
 851          * @return string
 852          */
 853         public function makeList( $a, $mode = LIST_COMMA, $binaryColumns = [] ) {
 854                 if ( !is_array( $a ) ) {
 855                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
 856                 }
 857
 858                 if ( $mode != LIST_NAMES ) {
 859                         // In MS SQL, values need to be specially encoded when they are
 860                         // inserted into binary fields. Perform this necessary encoding
 861                         // for the specified set of columns.
 862                         foreach ( array_keys( $a ) as $field ) {
 863                                 if ( !isset( $binaryColumns[$field] ) ) {
 864                                         continue;
 865                                 }
 866
 867                                 if ( is_array( $a[$field] ) ) {
 868                                         foreach ( $a[$field] as &$v ) {
 869                                                 $v = new MssqlBlob( $v );
 870                                         }
 871                                         unset( $v );
 872                                 } else {
 873                                         $a[$field] = new MssqlBlob( $a[$field] );
 874                                 }
 875                         }
 876                 }
 877
 878                 return parent::makeList( $a, $mode );
 879         }
 880
 881         /**
 882          * @param string $table
 883          * @param string $field
 884          * @return int Returns the size of a text field, or -1 for "unlimited"
 885          */
 886         public function textFieldSize( $table, $field ) {
 887                 $table = $this->tableName( $table );
 888                 $sql = "SELECT CHARACTER_MAXIMUM_LENGTH,DATA_TYPE FROM INFORMATION_SCHEMA.Columns
 889                         WHERE TABLE_NAME = '$table' AND COLUMN_NAME = '$field'";
 890                 $res = $this->query( $sql );
 891                 $row = $this->fetchRow( $res );
 892                 $size = -1;
 893                 if ( strtolower( $row['DATA_TYPE'] ) != 'text' ) {
 894                         $size = $row['CHARACTER_MAXIMUM_LENGTH'];
 895                 }
 896
 897                 return $size;
 898         }
 899
 900         /**
 901          * Construct a LIMIT query with optional offset
 902          * This is used for query pages
 903          *
 904          * @param string $sql SQL query we will append the limit too
 905          * @param int $limit The SQL limit
 906          * @param bool|int $offset The SQL offset (default false)
 907          * @return array|string
 908          * @throws DBUnexpectedError
 909          */
 910         public function limitResult( $sql, $limit, $offset = false ) {
 911                 if ( $offset === false || $offset == 0 ) {
 912                         if ( strpos( $sql, "SELECT" ) === false ) {
 913                                 return "TOP {$limit} " . $sql;
 914                         } else {
 915                                 return preg_replace( '/\bSELECT(\s+DISTINCT)?\b/Dsi',
 916                                         'SELECT$1 TOP ' . $limit, $sql, 1 );
 917                         }
 918                 } else {
 919                         // This one is fun, we need to pull out the select list as well as any ORDER BY clause
 920                         $select = $orderby = [];
 921                         $s1 = preg_match( '#SELECT\s+(.+?)\s+FROM#Dis', $sql, $select );
 922                         $s2 = preg_match( '#(ORDER BY\s+.+?)(\s*FOR XML .*)?$#Dis', $sql, $orderby );
 923                         $postOrder = '';
 924                         $first = $offset + 1;
 925                         $last = $offset + $limit;
 926                         $sub1 = 'sub_' . $this->subqueryId;
 927                         $sub2 = 'sub_' . ( $this->subqueryId + 1 );
 928                         $this->subqueryId += 2;
 929                         if ( !$s1 ) {
 930                                 // wat
 931                                 throw new DBUnexpectedError( $this, "Attempting to LIMIT a non-SELECT query\n" );
 932                         }
 933                         if ( !$s2 ) {
 934                                 // no ORDER BY
 935                                 $overOrder = 'ORDER BY (SELECT 1)';
 936                         } else {
 937                                 if ( !isset( $orderby[2] ) || !$orderby[2] ) {
 938                                         // don't need to strip it out if we're using a FOR XML clause
 939                                         $sql = str_replace( $orderby[1], '', $sql );
 940                                 }
 941                                 $overOrder = $orderby[1];
 942                                 $postOrder = ' ' . $overOrder;
 943                         }
 944                         $sql = "SELECT {$select[1]}
 945                                         FROM (
 946                                                 SELECT ROW_NUMBER() OVER({$overOrder}) AS rowNumber, *
 947                                                 FROM ({$sql}) {$sub1}
 948                                         ) {$sub2}
 949                                         WHERE rowNumber BETWEEN {$first} AND {$last}{$postOrder}";
 950
 951                         return $sql;
 952                 }
 953         }
 954
 955         /**
 956          * If there is a limit clause, parse it, strip it, and pass the remaining
 957          * SQL through limitResult() with the appropriate parameters. Not the
 958          * prettiest solution, but better than building a whole new parser. This
 959          * exists becase there are still too many extensions that don't use dynamic
 960          * sql generation.
 961          *
 962          * @param string $sql
 963          * @return array|mixed|string
 964          */
 965         public function LimitToTopN( $sql ) {
 966                 // Matches: LIMIT {[offset,] row_count | row_count OFFSET offset}
 967                 $pattern = '/\bLIMIT\s+((([0-9]+)\s*,\s*)?([0-9]+)(\s+OFFSET\s+([0-9]+))?)/i';
 968                 if ( preg_match( $pattern, $sql, $matches ) ) {
 969                         $row_count = $matches[4];
 970                         $offset = $matches[3] ?: $matches[6] ?: false;
 971
 972                         // strip the matching LIMIT clause out
 973                         $sql = str_replace( $matches[0], '', $sql );
 974
 975                         return $this->limitResult( $sql, $row_count, $offset );
 976                 }
 977
 978                 return $sql;
 979         }
 980
 981         /**
 982          * @return string Wikitext of a link to the server software's web site
 983          */
 984         public function getSoftwareLink() {
 985                 return "[{{int:version-db-mssql-url}} MS SQL Server]";
 986         }
 987
 988         /**
 989          * @return string Version information from the database
 990          */
 991         public function getServerVersion() {
 992                 $server_info = sqlsrv_server_info( $this->conn );
 993                 $version = $server_info['SQLServerVersion'] ?? 'Error';
 994
 995                 return $version;
 996         }
 997
 998         /**
 999          * @param string $table
1000          * @param string $fname
1001          * @return bool
1002          */
1003         public function tableExists( $table, $fname = __METHOD__ ) {
1004                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
1005
1006                 if ( $db !== false ) {
1007                         // remote database
1008                         $this->queryLogger->error( "Attempting to call tableExists on a remote table" );
1009                         return false;
1010                 }
1011
1012                 if ( $schema === false ) {
1013                         $schema = $this->dbSchema();
1014                 }
1015
1016                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.TABLES
1017                         WHERE TABLE_TYPE = 'BASE TABLE'
1018                         AND TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table'" );
1019
1020                 if ( $res->numRows() ) {
1021                         return true;
1022                 } else {
1023                         return false;
1024                 }
1025         }
1026
1027         /**
1028          * Query whether a given column exists in the mediawiki schema
1029          * @param string $table
1030          * @param string $field
1031          * @param string $fname
1032          * @return bool
1033          */
1034         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
1035                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
1036
1037                 if ( $db !== false ) {
1038                         // remote database
1039                         $this->queryLogger->error( "Attempting to call fieldExists on a remote table" );
1040                         return false;
1041                 }
1042
1043                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS
1044                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1045
1046                 if ( $res->numRows() ) {
1047                         return true;
1048                 } else {
1049                         return false;
1050                 }
1051         }
1052
1053         public function fieldInfo( $table, $field ) {
1054                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
1055
1056                 if ( $db !== false ) {
1057                         // remote database
1058                         $this->queryLogger->error( "Attempting to call fieldInfo on a remote table" );
1059                         return false;
1060                 }
1061
1062                 $res = $this->query( "SELECT * FROM INFORMATION_SCHEMA.COLUMNS
1063                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1064
1065                 $meta = $res->fetchRow();
1066                 if ( $meta ) {
1067                         return new MssqlField( $meta );
1068                 }
1069
1070                 return false;
1071         }
1072
1073         protected function doSavepoint( $identifier, $fname ) {
1074                 $this->query( 'SAVE TRANSACTION ' . $this->addIdentifierQuotes( $identifier ), $fname );
1075         }
1076
1077         protected function doReleaseSavepoint( $identifier, $fname ) {
1078                 // Not supported. Also not really needed, a new doSavepoint() for the
1079                 // same identifier will overwrite the old.
1080         }
1081
1082         protected function doRollbackToSavepoint( $identifier, $fname ) {
1083                 $this->query( 'ROLLBACK TRANSACTION ' . $this->addIdentifierQuotes( $identifier ), $fname );
1084         }
1085
1086         protected function doBegin( $fname = __METHOD__ ) {
1087                 if ( !sqlsrv_begin_transaction( $this->conn ) ) {
1088                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), 'BEGIN', $fname );
1089                 }
1090         }
1091
1092         /**
1093          * End a transaction
1094          * @param string $fname
1095          */
1096         protected function doCommit( $fname = __METHOD__ ) {
1097                 if ( !sqlsrv_commit( $this->conn ) ) {
1098                         $this->reportQueryError( $this->lastError(), $this->lastErrno(), 'COMMIT', $fname );
1099                 }
1100         }
1101
1102         /**
1103          * Rollback a transaction.
1104          * No-op on non-transactional databases.
1105          * @param string $fname
1106          */
1107         protected function doRollback( $fname = __METHOD__ ) {
1108                 if ( !sqlsrv_rollback( $this->conn ) ) {
1109                         $this->queryLogger->error(
1110                                 "{fname}\t{db_server}\t{errno}\t{error}\t",
1111                                 $this->getLogContext( [
1112                                         'errno' => $this->lastErrno(),
1113                                         'error' => $this->lastError(),
1114                                         'fname' => $fname,
1115                                         'trace' => ( new RuntimeException() )->getTraceAsString()
1116                                 ] )
1117                         );
1118                 }
1119         }
1120
1121         /**
1122          * @param string $s
1123          * @return string
1124          */
1125         public function strencode( $s ) {
1126                 // Should not be called by us
1127                 return str_replace( "'", "''", $s );
1128         }
1129
1130         /**
1131          * @param string|int|null|bool|Blob $s
1132          * @return string|int
1133          */
1134         public function addQuotes( $s ) {
1135                 if ( $s instanceof MssqlBlob ) {
1136                         return $s->fetch();
1137                 } elseif ( $s instanceof Blob ) {
1138                         // this shouldn't really ever be called, but it's here if needed
1139                         // (and will quite possibly make the SQL error out)
1140                         $blob = new MssqlBlob( $s->fetch() );
1141                         return $blob->fetch();
1142                 } else {
1143                         if ( is_bool( $s ) ) {
1144                                 $s = $s ? 1 : 0;
1145                         }
1146                         return parent::addQuotes( $s );
1147                 }
1148         }
1149
1150         /**
1151          * @param string $s
1152          * @return string
1153          */
1154         public function addIdentifierQuotes( $s ) {
1155                 // http://msdn.microsoft.com/en-us/library/aa223962.aspx
1156                 return '[' . $s . ']';
1157         }
1158
1159         /**
1160          * @param string $name
1161          * @return bool
1162          */
1163         public function isQuotedIdentifier( $name ) {
1164                 return strlen( $name ) && $name[0] == '[' && substr( $name, -1, 1 ) == ']';
1165         }
1166
1167         /**
1168          * MS SQL supports more pattern operators than other databases (ex: [,],^)
1169          *
1170          * @param string $s
1171          * @param string $escapeChar
1172          * @return string
1173          */
1174         protected function escapeLikeInternal( $s, $escapeChar = '`' ) {
1175                 return str_replace( [ $escapeChar, '%', '_', '[', ']', '^' ],
1176                         [ "{$escapeChar}{$escapeChar}", "{$escapeChar}%", "{$escapeChar}_",
1177                                 "{$escapeChar}[", "{$escapeChar}]", "{$escapeChar}^" ],
1178                         $s );
1179         }
1180
1181         protected function doSelectDomain( DatabaseDomain $domain ) {
1182                 if ( $domain->getSchema() !== null ) {
1183                         throw new DBExpectedError( $this, __CLASS__ . ": domain schemas are not supported." );
1184                 }
1185
1186                 $database = $domain->getDatabase();
1187                 if ( $database !== $this->getDBname() ) {
1188                         $sql = 'USE ' . $this->addIdentifierQuotes( $database );
1189                         list( $res, $err, $errno ) =
1190                                 $this->executeQuery( $sql, __METHOD__, self::QUERY_IGNORE_DBO_TRX );
1191
1192                         if ( $res === false ) {
1193                                 $this->reportQueryError( $err, $errno, $sql, __METHOD__ );
1194                                 return false; // unreachable
1195                         }
1196                 }
1197                 // Update that domain fields on success (no exception thrown)
1198                 $this->currentDomain = $domain;
1199
1200                 return true;
1201         }
1202
1203         /**
1204          * @param array $options An associative array of options to be turned into
1205          *   an SQL query, valid keys are listed in the function.
1206          * @return array
1207          */
1208         public function makeSelectOptions( $options ) {
1209                 $tailOpts = '';
1210                 $startOpts = '';
1211
1212                 $noKeyOptions = [];
1213                 foreach ( $options as $key => $option ) {
1214                         if ( is_numeric( $key ) ) {
1215                                 $noKeyOptions[$option] = true;
1216                         }
1217                 }
1218
1219                 $tailOpts .= $this->makeGroupByWithHaving( $options );
1220
1221                 $tailOpts .= $this->makeOrderBy( $options );
1222
1223                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1224                         $startOpts .= 'DISTINCT';
1225                 }
1226
1227                 if ( isset( $noKeyOptions['FOR XML'] ) ) {
1228                         // used in group concat field emulation
1229                         $tailOpts .= " FOR XML PATH('')";
1230                 }
1231
1232                 // we want this to be compatible with the output of parent::makeSelectOptions()
1233                 return [ $startOpts, '', $tailOpts, '', '' ];
1234         }
1235
1236         public function getType() {
1237                 return 'mssql';
1238         }
1239
1240         /**
1241          * @param array $stringList
1242          * @return string
1243          */
1244         public function buildConcat( $stringList ) {
1245                 return implode( ' + ', $stringList );
1246         }
1247
1248         /**
1249          * Build a GROUP_CONCAT or equivalent statement for a query.
1250          * MS SQL doesn't have GROUP_CONCAT so we emulate it with other stuff (and boy is it nasty)
1251          *
1252          * This is useful for combining a field for several rows into a single string.
1253          * NULL values will not appear in the output, duplicated values will appear,
1254          * and the resulting delimiter-separated values have no defined sort order.
1255          * Code using the results may need to use the PHP unique() or sort() methods.
1256          *
1257          * @param string $delim Glue to bind the results together
1258          * @param string|array $table Table name
1259          * @param string $field Field name
1260          * @param string|array $conds Conditions
1261          * @param string|array $join_conds Join conditions
1262          * @return string SQL text
1263          * @since 1.23
1264          */
1265         public function buildGroupConcatField( $delim, $table, $field, $conds = '',
1266                 $join_conds = []
1267         ) {
1268                 $gcsq = 'gcsq_' . $this->subqueryId;
1269                 $this->subqueryId++;
1270
1271                 $delimLen = strlen( $delim );
1272                 $fld = "{$field} + {$this->addQuotes( $delim )}";
1273                 $sql = "(SELECT LEFT({$field}, LEN({$field}) - {$delimLen}) FROM ("
1274                         . $this->selectSQLText( $table, $fld, $conds, null, [ 'FOR XML' ], $join_conds )
1275                         . ") {$gcsq} ({$field}))";
1276
1277                 return $sql;
1278         }
1279
1280         public function buildSubstring( $input, $startPosition, $length = null ) {
1281                 $this->assertBuildSubstringParams( $startPosition, $length );
1282                 if ( $length === null ) {
1283                         /**
1284                          * MSSQL doesn't allow an empty length parameter, so when we don't want to limit the
1285                          * length returned use the default maximum size of text.
1286                          * @see https://docs.microsoft.com/en-us/sql/t-sql/statements/set-textsize-transact-sql
1287                          */
1288                         $length = 2147483647;
1289                 }
1290                 return 'SUBSTRING(' . implode( ',', [ $input, $startPosition, $length ] ) . ')';
1291         }
1292
1293         /**
1294          * Returns an associative array for fields that are of type varbinary, binary, or image
1295          * $table can be either a raw table name or passed through tableName() first
1296          * @param string $table
1297          * @return array
1298          */
1299         private function getBinaryColumns( $table ) {
1300                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1301                 $tableRaw = array_pop( $tableRawArr );
1302
1303                 if ( $this->binaryColumnCache === null ) {
1304                         $this->populateColumnCaches();
1305                 }
1306
1307                 return $this->binaryColumnCache[$tableRaw] ?? [];
1308         }
1309
1310         /**
1311          * @param string $table
1312          * @return array
1313          */
1314         private function getBitColumns( $table ) {
1315                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1316                 $tableRaw = array_pop( $tableRawArr );
1317
1318                 if ( $this->bitColumnCache === null ) {
1319                         $this->populateColumnCaches();
1320                 }
1321
1322                 return $this->bitColumnCache[$tableRaw] ?? [];
1323         }
1324
1325         private function populateColumnCaches() {
1326                 $res = $this->select( 'INFORMATION_SCHEMA.COLUMNS', '*',
1327                         [
1328                                 'TABLE_CATALOG' => $this->getDBname(),
1329                                 'TABLE_SCHEMA' => $this->dbSchema(),
1330                                 'DATA_TYPE' => [ 'varbinary', 'binary', 'image', 'bit' ]
1331                         ] );
1332
1333                 $this->binaryColumnCache = [];
1334                 $this->bitColumnCache = [];
1335                 foreach ( $res as $row ) {
1336                         if ( $row->DATA_TYPE == 'bit' ) {
1337                                 $this->bitColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1338                         } else {
1339                                 $this->binaryColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1340                         }
1341                 }
1342         }
1343
1344         /**
1345          * @param string $name
1346          * @param string $format One of "quoted" (default), "raw", or "split".
1347          * @return string|array When the requested $format is "split", a list of database, schema, and
1348          *  table name is returned. Database and schema can be `false`.
1349          */
1350         function tableName( $name, $format = 'quoted' ) {
1351                 # Replace reserved words with better ones
1352                 switch ( $name ) {
1353                         case 'user':
1354                                 return $this->realTableName( 'mwuser', $format );
1355                         default:
1356                                 return $this->realTableName( $name, $format );
1357                 }
1358         }
1359
1360         /**
1361          * call this instead of tableName() in the updater when renaming tables
1362          * @param string $name
1363          * @param string $format One of "quoted" (default), "raw", or "split".
1364          * @return string|array When the requested $format is "split", a list of database, schema, and
1365          *  table name is returned. Database and schema can be `false`.
1366          * @private
1367          */
1368         function realTableName( $name, $format = 'quoted' ) {
1369                 $table = parent::tableName( $name, $format );
1370                 if ( $format == 'split' ) {
1371                         // Used internally, we want the schema split off from the table name and returned
1372                         // as a list with 3 elements (database, schema, table)
1373                         return array_pad( explode( '.', $table, 3 ), -3, false );
1374                 }
1375                 return $table;
1376         }
1377
1378         /**
1379          * Delete a table
1380          * @param string $tableName
1381          * @param string $fName
1382          * @return bool|IResultWrapper
1383          * @since 1.18
1384          */
1385         public function dropTable( $tableName, $fName = __METHOD__ ) {
1386                 if ( !$this->tableExists( $tableName, $fName ) ) {
1387                         return false;
1388                 }
1389
1390                 // parent function incorrectly appends CASCADE, which we don't want
1391                 $sql = "DROP TABLE " . $this->tableName( $tableName );
1392
1393                 return $this->query( $sql, $fName );
1394         }
1395
1396         /**
1397          * Called in the installer and updater.
1398          * Probably doesn't need to be called anywhere else in the codebase.
1399          * @param bool|null $value
1400          * @return bool|null
1401          */
1402         public function prepareStatements( $value = null ) {
1403                 $old = $this->prepareStatements;
1404                 if ( $value !== null ) {
1405                         $this->prepareStatements = $value;
1406                 }
1407
1408                 return $old;
1409         }
1410
1411         /**
1412          * Called in the installer and updater.
1413          * Probably doesn't need to be called anywhere else in the codebase.
1414          * @param bool|null $value
1415          * @return bool|null
1416          */
1417         public function scrollableCursor( $value = null ) {
1418                 $old = $this->scrollableCursor;
1419                 if ( $value !== null ) {
1420                         $this->scrollableCursor = $value;
1421                 }
1422
1423                 return $old;
1424         }
1425
1426         public function buildStringCast( $field ) {
1427                 return "CAST( $field AS NVARCHAR )";
1428         }
1429
1430         public static function getAttributes() {
1431                 return [ self::ATTR_SCHEMAS_AS_TABLE_GROUPS => true ];
1432         }
1433 }
1434
1435 /**
1436  * @deprecated since 1.29
1437  */
1438 class_alias( DatabaseMssql::class, 'DatabaseMssql' );