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 /**
  29  * @ingroup Database
  30  */
  31 class DatabaseMssql extends Database {
  32         protected $mPort;
  33         protected $mUseWindowsAuth = false;
  34
  35         protected $mInsertId = null;
  36         protected $mLastResult = null;
  37         protected $mAffectedRows = null;
  38         protected $mSubqueryId = 0;
  39         protected $mScrollableCursor = true;
  40         protected $mPrepareStatements = true;
  41         protected $mBinaryColumnCache = null;
  42         protected $mBitColumnCache = null;
  43         protected $mIgnoreDupKeyErrors = false;
  44         protected $mIgnoreErrors = [];
  45
  46         public function implicitGroupby() {
  47                 return false;
  48         }
  49
  50         public function implicitOrderby() {
  51                 return false;
  52         }
  53
  54         public function unionSupportsOrderAndLimit() {
  55                 return false;
  56         }
  57
  58         public function __construct( array $params ) {
  59                 $this->mPort = $params['port'];
  60                 $this->mUseWindowsAuth = $params['UseWindowsAuth'];
  61
  62                 parent::__construct( $params );
  63         }
  64
  65         /**
  66          * Usually aborts on failure
  67          * @param string $server
  68          * @param string $user
  69          * @param string $password
  70          * @param string $dbName
  71          * @throws DBConnectionError
  72          * @return bool|resource|null
  73          */
  74         public function open( $server, $user, $password, $dbName ) {
  75                 # Test for driver support, to avoid suppressed fatal error
  76                 if ( !function_exists( 'sqlsrv_connect' ) ) {
  77                         throw new DBConnectionError(
  78                                 $this,
  79                                 "Microsoft SQL Server Native (sqlsrv) functions missing.
  80                                 You can download the driver from: http://go.microsoft.com/fwlink/?LinkId=123470\n"
  81                         );
  82                 }
  83
  84                 # e.g. the class is being loaded
  85                 if ( !strlen( $user ) ) {
  86                         return null;
  87                 }
  88
  89                 $this->close();
  90                 $this->mServer = $server;
  91                 $this->mUser = $user;
  92                 $this->mPassword = $password;
  93                 $this->mDBname = $dbName;
  94
  95                 $connectionInfo = [];
  96
  97                 if ( $dbName ) {
  98                         $connectionInfo['Database'] = $dbName;
  99                 }
 100
 101                 // Decide which auth scenerio to use
 102                 // if we are using Windows auth, then don't add credentials to $connectionInfo
 103                 if ( !$this->mUseWindowsAuth ) {
 104                         $connectionInfo['UID'] = $user;
 105                         $connectionInfo['PWD'] = $password;
 106                 }
 107
 108                 MediaWiki\suppressWarnings();
 109                 $this->mConn = sqlsrv_connect( $server, $connectionInfo );
 110                 MediaWiki\restoreWarnings();
 111
 112                 if ( $this->mConn === false ) {
 113                         throw new DBConnectionError( $this, $this->lastError() );
 114                 }
 115
 116                 $this->mOpened = true;
 117
 118                 return $this->mConn;
 119         }
 120
 121         /**
 122          * Closes a database connection, if it is open
 123          * Returns success, true if already closed
 124          * @return bool
 125          */
 126         protected function closeConnection() {
 127                 return sqlsrv_close( $this->mConn );
 128         }
 129
 130         /**
 131          * @param bool|MssqlResultWrapper|resource $result
 132          * @return bool|MssqlResultWrapper
 133          */
 134         protected function resultObject( $result ) {
 135                 if ( !$result ) {
 136                         return false;
 137                 } elseif ( $result instanceof MssqlResultWrapper ) {
 138                         return $result;
 139                 } elseif ( $result === true ) {
 140                         // Successful write query
 141                         return $result;
 142                 } else {
 143                         return new MssqlResultWrapper( $this, $result );
 144                 }
 145         }
 146
 147         /**
 148          * @param string $sql
 149          * @return bool|MssqlResultWrapper|resource
 150          * @throws DBUnexpectedError
 151          */
 152         protected function doQuery( $sql ) {
 153                 // several extensions seem to think that all databases support limits
 154                 // via LIMIT N after the WHERE clause, but  MSSQL uses SELECT TOP N,
 155                 // so to catch any of those extensions we'll do a quick check for a
 156                 // LIMIT clause and pass $sql through $this->LimitToTopN() which parses
 157                 // the LIMIT clause and passes the result to $this->limitResult();
 158                 if ( preg_match( '/\bLIMIT\s*/i', $sql ) ) {
 159                         // massage LIMIT -> TopN
 160                         $sql = $this->LimitToTopN( $sql );
 161                 }
 162
 163                 // MSSQL doesn't have EXTRACT(epoch FROM XXX)
 164                 if ( preg_match( '#\bEXTRACT\s*?\(\s*?EPOCH\s+FROM\b#i', $sql, $matches ) ) {
 165                         // This is same as UNIX_TIMESTAMP, we need to calc # of seconds from 1970
 166                         $sql = str_replace( $matches[0], "DATEDIFF(s,CONVERT(datetime,'1/1/1970'),", $sql );
 167                 }
 168
 169                 // perform query
 170
 171                 // SQLSRV_CURSOR_STATIC is slower than SQLSRV_CURSOR_CLIENT_BUFFERED (one of the two is
 172                 // needed if we want to be able to seek around the result set), however CLIENT_BUFFERED
 173                 // has a bug in the sqlsrv driver where wchar_t types (such as nvarchar) that are empty
 174                 // strings make php throw a fatal error "Severe error translating Unicode"
 175                 if ( $this->mScrollableCursor ) {
 176                         $scrollArr = [ 'Scrollable' => SQLSRV_CURSOR_STATIC ];
 177                 } else {
 178                         $scrollArr = [];
 179                 }
 180
 181                 if ( $this->mPrepareStatements ) {
 182                         // we do prepare + execute so we can get its field metadata for later usage if desired
 183                         $stmt = sqlsrv_prepare( $this->mConn, $sql, [], $scrollArr );
 184                         $success = sqlsrv_execute( $stmt );
 185                 } else {
 186                         $stmt = sqlsrv_query( $this->mConn, $sql, [], $scrollArr );
 187                         $success = (bool)$stmt;
 188                 }
 189
 190                 // Make a copy to ensure what we add below does not get reflected in future queries
 191                 $ignoreErrors = $this->mIgnoreErrors;
 192
 193                 if ( $this->mIgnoreDupKeyErrors ) {
 194                         // ignore duplicate key errors
 195                         // this emulates INSERT IGNORE in MySQL
 196                         $ignoreErrors[] = '2601'; // duplicate key error caused by unique index
 197                         $ignoreErrors[] = '2627'; // duplicate key error caused by primary key
 198                         $ignoreErrors[] = '3621'; // generic "the statement has been terminated" error
 199                 }
 200
 201                 if ( $success === false ) {
 202                         $errors = sqlsrv_errors();
 203                         $success = true;
 204
 205                         foreach ( $errors as $err ) {
 206                                 if ( !in_array( $err['code'], $ignoreErrors ) ) {
 207                                         $success = false;
 208                                         break;
 209                                 }
 210                         }
 211
 212                         if ( $success === false ) {
 213                                 return false;
 214                         }
 215                 }
 216                 // remember number of rows affected
 217                 $this->mAffectedRows = sqlsrv_rows_affected( $stmt );
 218
 219                 return $stmt;
 220         }
 221
 222         public function freeResult( $res ) {
 223                 if ( $res instanceof ResultWrapper ) {
 224                         $res = $res->result;
 225                 }
 226
 227                 sqlsrv_free_stmt( $res );
 228         }
 229
 230         /**
 231          * @param MssqlResultWrapper $res
 232          * @return stdClass
 233          */
 234         public function fetchObject( $res ) {
 235                 // $res is expected to be an instance of MssqlResultWrapper here
 236                 return $res->fetchObject();
 237         }
 238
 239         /**
 240          * @param MssqlResultWrapper $res
 241          * @return array
 242          */
 243         public function fetchRow( $res ) {
 244                 return $res->fetchRow();
 245         }
 246
 247         /**
 248          * @param mixed $res
 249          * @return int
 250          */
 251         public function numRows( $res ) {
 252                 if ( $res instanceof ResultWrapper ) {
 253                         $res = $res->result;
 254                 }
 255
 256                 $ret = sqlsrv_num_rows( $res );
 257
 258                 if ( $ret === false ) {
 259                         // we cannot get an amount of rows from this cursor type
 260                         // has_rows returns bool true/false if the result has rows
 261                         $ret = (int)sqlsrv_has_rows( $res );
 262                 }
 263
 264                 return $ret;
 265         }
 266
 267         /**
 268          * @param mixed $res
 269          * @return int
 270          */
 271         public function numFields( $res ) {
 272                 if ( $res instanceof ResultWrapper ) {
 273                         $res = $res->result;
 274                 }
 275
 276                 return sqlsrv_num_fields( $res );
 277         }
 278
 279         /**
 280          * @param mixed $res
 281          * @param int $n
 282          * @return int
 283          */
 284         public function fieldName( $res, $n ) {
 285                 if ( $res instanceof ResultWrapper ) {
 286                         $res = $res->result;
 287                 }
 288
 289                 return sqlsrv_field_metadata( $res )[$n]['Name'];
 290         }
 291
 292         /**
 293          * This must be called after nextSequenceVal
 294          * @return int|null
 295          */
 296         public function insertId() {
 297                 return $this->mInsertId;
 298         }
 299
 300         /**
 301          * @param MssqlResultWrapper $res
 302          * @param int $row
 303          * @return bool
 304          */
 305         public function dataSeek( $res, $row ) {
 306                 return $res->seek( $row );
 307         }
 308
 309         /**
 310          * @return string
 311          */
 312         public function lastError() {
 313                 $strRet = '';
 314                 $retErrors = sqlsrv_errors( SQLSRV_ERR_ALL );
 315                 if ( $retErrors != null ) {
 316                         foreach ( $retErrors as $arrError ) {
 317                                 $strRet .= $this->formatError( $arrError ) . "\n";
 318                         }
 319                 } else {
 320                         $strRet = "No errors found";
 321                 }
 322
 323                 return $strRet;
 324         }
 325
 326         /**
 327          * @param array $err
 328          * @return string
 329          */
 330         private function formatError( $err ) {
 331                 return '[SQLSTATE ' .
 332                         $err['SQLSTATE'] . '][Error Code ' . $err['code'] . ']' . $err['message'];
 333         }
 334
 335         /**
 336          * @return string|int
 337          */
 338         public function lastErrno() {
 339                 $err = sqlsrv_errors( SQLSRV_ERR_ALL );
 340                 if ( $err !== null && isset( $err[0] ) ) {
 341                         return $err[0]['code'];
 342                 } else {
 343                         return 0;
 344                 }
 345         }
 346
 347         /**
 348          * @return int
 349          */
 350         public function affectedRows() {
 351                 return $this->mAffectedRows;
 352         }
 353
 354         /**
 355          * SELECT wrapper
 356          *
 357          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 358          * @param mixed $vars Array or string, field name(s) to be retrieved
 359          * @param mixed $conds Array or string, condition(s) for WHERE
 360          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 361          * @param array $options Associative array of options (e.g.
 362          *   [ 'GROUP BY' => 'page_title' ]), see Database::makeSelectOptions
 363          *   code for list of supported stuff
 364          * @param array $join_conds Associative array of table join conditions
 365          *   (optional) (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 366          * @return mixed Database result resource (feed to Database::fetchObject
 367          *   or whatever), or false on failure
 368          * @throws DBQueryError
 369          * @throws DBUnexpectedError
 370          * @throws Exception
 371          */
 372         public function select( $table, $vars, $conds = '', $fname = __METHOD__,
 373                 $options = [], $join_conds = []
 374         ) {
 375                 $sql = $this->selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 376                 if ( isset( $options['EXPLAIN'] ) ) {
 377                         try {
 378                                 $this->mScrollableCursor = false;
 379                                 $this->mPrepareStatements = false;
 380                                 $this->query( "SET SHOWPLAN_ALL ON" );
 381                                 $ret = $this->query( $sql, $fname );
 382                                 $this->query( "SET SHOWPLAN_ALL OFF" );
 383                         } catch ( DBQueryError $dqe ) {
 384                                 if ( isset( $options['FOR COUNT'] ) ) {
 385                                         // likely don't have privs for SHOWPLAN, so run a select count instead
 386                                         $this->query( "SET SHOWPLAN_ALL OFF" );
 387                                         unset( $options['EXPLAIN'] );
 388                                         $ret = $this->select(
 389                                                 $table,
 390                                                 'COUNT(*) AS EstimateRows',
 391                                                 $conds,
 392                                                 $fname,
 393                                                 $options,
 394                                                 $join_conds
 395                                         );
 396                                 } else {
 397                                         // someone actually wanted the query plan instead of an est row count
 398                                         // let them know of the error
 399                                         $this->mScrollableCursor = true;
 400                                         $this->mPrepareStatements = true;
 401                                         throw $dqe;
 402                                 }
 403                         }
 404                         $this->mScrollableCursor = true;
 405                         $this->mPrepareStatements = true;
 406                         return $ret;
 407                 }
 408                 return $this->query( $sql, $fname );
 409         }
 410
 411         /**
 412          * SELECT wrapper
 413          *
 414          * @param mixed $table Array or string, table name(s) (prefix auto-added)
 415          * @param mixed $vars Array or string, field name(s) to be retrieved
 416          * @param mixed $conds Array or string, condition(s) for WHERE
 417          * @param string $fname Calling function name (use __METHOD__) for logs/profiling
 418          * @param array $options Associative array of options (e.g. [ 'GROUP BY' => 'page_title' ]),
 419          *   see Database::makeSelectOptions code for list of supported stuff
 420          * @param array $join_conds Associative array of table join conditions (optional)
 421          *    (e.g. [ 'page' => [ 'LEFT JOIN','page_latest=rev_id' ] ]
 422          * @return string The SQL text
 423          */
 424         public function selectSQLText( $table, $vars, $conds = '', $fname = __METHOD__,
 425                 $options = [], $join_conds = []
 426         ) {
 427                 if ( isset( $options['EXPLAIN'] ) ) {
 428                         unset( $options['EXPLAIN'] );
 429                 }
 430
 431                 $sql = parent::selectSQLText( $table, $vars, $conds, $fname, $options, $join_conds );
 432
 433                 // try to rewrite aggregations of bit columns (currently MAX and MIN)
 434                 if ( strpos( $sql, 'MAX(' ) !== false || strpos( $sql, 'MIN(' ) !== false ) {
 435                         $bitColumns = [];
 436                         if ( is_array( $table ) ) {
 437                                 foreach ( $table as $t ) {
 438                                         $bitColumns += $this->getBitColumns( $this->tableName( $t ) );
 439                                 }
 440                         } else {
 441                                 $bitColumns = $this->getBitColumns( $this->tableName( $table ) );
 442                         }
 443
 444                         foreach ( $bitColumns as $col => $info ) {
 445                                 $replace = [
 446                                         "MAX({$col})" => "MAX(CAST({$col} AS tinyint))",
 447                                         "MIN({$col})" => "MIN(CAST({$col} AS tinyint))",
 448                                 ];
 449                                 $sql = str_replace( array_keys( $replace ), array_values( $replace ), $sql );
 450                         }
 451                 }
 452
 453                 return $sql;
 454         }
 455
 456         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds,
 457                 $fname = __METHOD__
 458         ) {
 459                 $this->mScrollableCursor = false;
 460                 try {
 461                         parent::deleteJoin( $delTable, $joinTable, $delVar, $joinVar, $conds, $fname );
 462                 } catch ( Exception $e ) {
 463                         $this->mScrollableCursor = true;
 464                         throw $e;
 465                 }
 466                 $this->mScrollableCursor = true;
 467         }
 468
 469         public function delete( $table, $conds, $fname = __METHOD__ ) {
 470                 $this->mScrollableCursor = false;
 471                 try {
 472                         parent::delete( $table, $conds, $fname );
 473                 } catch ( Exception $e ) {
 474                         $this->mScrollableCursor = true;
 475                         throw $e;
 476                 }
 477                 $this->mScrollableCursor = true;
 478         }
 479
 480         /**
 481          * Estimate rows in dataset
 482          * Returns estimated count, based on SHOWPLAN_ALL output
 483          * This is not necessarily an accurate estimate, so use sparingly
 484          * Returns -1 if count cannot be found
 485          * Takes same arguments as Database::select()
 486          * @param string $table
 487          * @param string $vars
 488          * @param string $conds
 489          * @param string $fname
 490          * @param array $options
 491          * @return int
 492          */
 493         public function estimateRowCount( $table, $vars = '*', $conds = '',
 494                 $fname = __METHOD__, $options = []
 495         ) {
 496                 // http://msdn2.microsoft.com/en-us/library/aa259203.aspx
 497                 $options['EXPLAIN'] = true;
 498                 $options['FOR COUNT'] = true;
 499                 $res = $this->select( $table, $vars, $conds, $fname, $options );
 500
 501                 $rows = -1;
 502                 if ( $res ) {
 503                         $row = $this->fetchRow( $res );
 504
 505                         if ( isset( $row['EstimateRows'] ) ) {
 506                                 $rows = (int)$row['EstimateRows'];
 507                         }
 508                 }
 509
 510                 return $rows;
 511         }
 512
 513         /**
 514          * Returns information about an index
 515          * If errors are explicitly ignored, returns NULL on failure
 516          * @param string $table
 517          * @param string $index
 518          * @param string $fname
 519          * @return array|bool|null
 520          */
 521         public function indexInfo( $table, $index, $fname = __METHOD__ ) {
 522                 # This does not return the same info as MYSQL would, but that's OK
 523                 # because MediaWiki never uses the returned value except to check for
 524                 # the existence of indexes.
 525                 $sql = "sp_helpindex '" . $this->tableName( $table ) . "'";
 526                 $res = $this->query( $sql, $fname );
 527
 528                 if ( !$res ) {
 529                         return null;
 530                 }
 531
 532                 $result = [];
 533                 foreach ( $res as $row ) {
 534                         if ( $row->index_name == $index ) {
 535                                 $row->Non_unique = !stristr( $row->index_description, "unique" );
 536                                 $cols = explode( ", ", $row->index_keys );
 537                                 foreach ( $cols as $col ) {
 538                                         $row->Column_name = trim( $col );
 539                                         $result[] = clone $row;
 540                                 }
 541                         } elseif ( $index == 'PRIMARY' && stristr( $row->index_description, 'PRIMARY' ) ) {
 542                                 $row->Non_unique = 0;
 543                                 $cols = explode( ", ", $row->index_keys );
 544                                 foreach ( $cols as $col ) {
 545                                         $row->Column_name = trim( $col );
 546                                         $result[] = clone $row;
 547                                 }
 548                         }
 549                 }
 550
 551                 return empty( $result ) ? false : $result;
 552         }
 553
 554         /**
 555          * INSERT wrapper, inserts an array into a table
 556          *
 557          * $arrToInsert may be a single associative array, or an array of these with numeric keys, for
 558          * multi-row insert.
 559          *
 560          * Usually aborts on failure
 561          * If errors are explicitly ignored, returns success
 562          * @param string $table
 563          * @param array $arrToInsert
 564          * @param string $fname
 565          * @param array $options
 566          * @return bool
 567          * @throws Exception
 568          */
 569         public function insert( $table, $arrToInsert, $fname = __METHOD__, $options = [] ) {
 570                 # No rows to insert, easy just return now
 571                 if ( !count( $arrToInsert ) ) {
 572                         return true;
 573                 }
 574
 575                 if ( !is_array( $options ) ) {
 576                         $options = [ $options ];
 577                 }
 578
 579                 $table = $this->tableName( $table );
 580
 581                 if ( !( isset( $arrToInsert[0] ) && is_array( $arrToInsert[0] ) ) ) { // Not multi row
 582                         $arrToInsert = [ 0 => $arrToInsert ]; // make everything multi row compatible
 583                 }
 584
 585                 // We know the table we're inserting into, get its identity column
 586                 $identity = null;
 587                 // strip matching square brackets and the db/schema from table name
 588                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
 589                 $tableRaw = array_pop( $tableRawArr );
 590                 $res = $this->doQuery(
 591                         "SELECT NAME AS idColumn FROM SYS.IDENTITY_COLUMNS " .
 592                                 "WHERE OBJECT_NAME(OBJECT_ID)='{$tableRaw}'"
 593                 );
 594                 if ( $res && sqlsrv_has_rows( $res ) ) {
 595                         // There is an identity for this table.
 596                         $identityArr = sqlsrv_fetch_array( $res, SQLSRV_FETCH_ASSOC );
 597                         $identity = array_pop( $identityArr );
 598                 }
 599                 sqlsrv_free_stmt( $res );
 600
 601                 // Determine binary/varbinary fields so we can encode data as a hex string like 0xABCDEF
 602                 $binaryColumns = $this->getBinaryColumns( $table );
 603
 604                 // INSERT IGNORE is not supported by SQL Server
 605                 // remove IGNORE from options list and set ignore flag to true
 606                 if ( in_array( 'IGNORE', $options ) ) {
 607                         $options = array_diff( $options, [ 'IGNORE' ] );
 608                         $this->mIgnoreDupKeyErrors = true;
 609                 }
 610
 611                 $ret = null;
 612                 foreach ( $arrToInsert as $a ) {
 613                         // start out with empty identity column, this is so we can return
 614                         // it as a result of the INSERT logic
 615                         $sqlPre = '';
 616                         $sqlPost = '';
 617                         $identityClause = '';
 618
 619                         // if we have an identity column
 620                         if ( $identity ) {
 621                                 // iterate through
 622                                 foreach ( $a as $k => $v ) {
 623                                         if ( $k == $identity ) {
 624                                                 if ( !is_null( $v ) ) {
 625                                                         // there is a value being passed to us,
 626                                                         // we need to turn on and off inserted identity
 627                                                         $sqlPre = "SET IDENTITY_INSERT $table ON;";
 628                                                         $sqlPost = ";SET IDENTITY_INSERT $table OFF;";
 629                                                 } else {
 630                                                         // we can't insert NULL into an identity column,
 631                                                         // so remove the column from the insert.
 632                                                         unset( $a[$k] );
 633                                                 }
 634                                         }
 635                                 }
 636
 637                                 // we want to output an identity column as result
 638                                 $identityClause = "OUTPUT INSERTED.$identity ";
 639                         }
 640
 641                         $keys = array_keys( $a );
 642
 643                         // Build the actual query
 644                         $sql = $sqlPre . 'INSERT ' . implode( ' ', $options ) .
 645                                 " INTO $table (" . implode( ',', $keys ) . ") $identityClause VALUES (";
 646
 647                         $first = true;
 648                         foreach ( $a as $key => $value ) {
 649                                 if ( isset( $binaryColumns[$key] ) ) {
 650                                         $value = new MssqlBlob( $value );
 651                                 }
 652                                 if ( $first ) {
 653                                         $first = false;
 654                                 } else {
 655                                         $sql .= ',';
 656                                 }
 657                                 if ( is_null( $value ) ) {
 658                                         $sql .= 'null';
 659                                 } elseif ( is_array( $value ) || is_object( $value ) ) {
 660                                         if ( is_object( $value ) && $value instanceof Blob ) {
 661                                                 $sql .= $this->addQuotes( $value );
 662                                         } else {
 663                                                 $sql .= $this->addQuotes( serialize( $value ) );
 664                                         }
 665                                 } else {
 666                                         $sql .= $this->addQuotes( $value );
 667                                 }
 668                         }
 669                         $sql .= ')' . $sqlPost;
 670
 671                         // Run the query
 672                         $this->mScrollableCursor = false;
 673                         try {
 674                                 $ret = $this->query( $sql );
 675                         } catch ( Exception $e ) {
 676                                 $this->mScrollableCursor = true;
 677                                 $this->mIgnoreDupKeyErrors = false;
 678                                 throw $e;
 679                         }
 680                         $this->mScrollableCursor = true;
 681
 682                         if ( $ret instanceof ResultWrapper && !is_null( $identity ) ) {
 683                                 // Then we want to get the identity column value we were assigned and save it off
 684                                 $row = $ret->fetchObject();
 685                                 if ( is_object( $row ) ) {
 686                                         $this->mInsertId = $row->$identity;
 687                                         // It seems that mAffectedRows is -1 sometimes when OUTPUT INSERTED.identity is
 688                                         // used if we got an identity back, we know for sure a row was affected, so
 689                                         // adjust that here
 690                                         if ( $this->mAffectedRows == -1 ) {
 691                                                 $this->mAffectedRows = 1;
 692                                         }
 693                                 }
 694                         }
 695                 }
 696
 697                 $this->mIgnoreDupKeyErrors = false;
 698
 699                 return $ret;
 700         }
 701
 702         /**
 703          * INSERT SELECT wrapper
 704          * $varMap must be an associative array of the form [ 'dest1' => 'source1', ... ]
 705          * Source items may be literals rather than field names, but strings should
 706          * be quoted with Database::addQuotes().
 707          * @param string $destTable
 708          * @param array|string $srcTable May be an array of tables.
 709          * @param array $varMap
 710          * @param array $conds May be "*" to copy the whole table.
 711          * @param string $fname
 712          * @param array $insertOptions
 713          * @param array $selectOptions
 714          * @return null|ResultWrapper
 715          * @throws Exception
 716          */
 717         public function nativeInsertSelect( $destTable, $srcTable, $varMap, $conds, $fname = __METHOD__,
 718                 $insertOptions = [], $selectOptions = []
 719         ) {
 720                 $this->mScrollableCursor = false;
 721                 try {
 722                         $ret = parent::nativeInsertSelect(
 723                                 $destTable,
 724                                 $srcTable,
 725                                 $varMap,
 726                                 $conds,
 727                                 $fname,
 728                                 $insertOptions,
 729                                 $selectOptions
 730                         );
 731                 } catch ( Exception $e ) {
 732                         $this->mScrollableCursor = true;
 733                         throw $e;
 734                 }
 735                 $this->mScrollableCursor = true;
 736
 737                 return $ret;
 738         }
 739
 740         /**
 741          * UPDATE wrapper. Takes a condition array and a SET array.
 742          *
 743          * @param string $table Name of the table to UPDATE. This will be passed through
 744          *                Database::tableName().
 745          *
 746          * @param array $values An array of values to SET. For each array element,
 747          *                the key gives the field name, and the value gives the data
 748          *                to set that field to. The data will be quoted by
 749          *                Database::addQuotes().
 750          *
 751          * @param array $conds An array of conditions (WHERE). See
 752          *                Database::select() for the details of the format of
 753          *                condition arrays. Use '*' to update all rows.
 754          *
 755          * @param string $fname The function name of the caller (from __METHOD__),
 756          *                for logging and profiling.
 757          *
 758          * @param array $options An array of UPDATE options, can be:
 759          *                   - IGNORE: Ignore unique key conflicts
 760          *                   - LOW_PRIORITY: MySQL-specific, see MySQL manual.
 761          * @return bool
 762          * @throws DBUnexpectedError
 763          * @throws Exception
 764          */
 765         function update( $table, $values, $conds, $fname = __METHOD__, $options = [] ) {
 766                 $table = $this->tableName( $table );
 767                 $binaryColumns = $this->getBinaryColumns( $table );
 768
 769                 $opts = $this->makeUpdateOptions( $options );
 770                 $sql = "UPDATE $opts $table SET " . $this->makeList( $values, LIST_SET, $binaryColumns );
 771
 772                 if ( $conds !== [] && $conds !== '*' ) {
 773                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND, $binaryColumns );
 774                 }
 775
 776                 $this->mScrollableCursor = false;
 777                 try {
 778                         $this->query( $sql );
 779                 } catch ( Exception $e ) {
 780                         $this->mScrollableCursor = true;
 781                         throw $e;
 782                 }
 783                 $this->mScrollableCursor = true;
 784                 return true;
 785         }
 786
 787         /**
 788          * Makes an encoded list of strings from an array
 789          * @param array $a Containing the data
 790          * @param int $mode Constant
 791          *      - LIST_COMMA:          comma separated, no field names
 792          *      - LIST_AND:            ANDed WHERE clause (without the WHERE). See
 793          *        the documentation for $conds in Database::select().
 794          *      - LIST_OR:             ORed WHERE clause (without the WHERE)
 795          *      - LIST_SET:            comma separated with field names, like a SET clause
 796          *      - LIST_NAMES:          comma separated field names
 797          * @param array $binaryColumns Contains a list of column names that are binary types
 798          *      This is a custom parameter only present for MS SQL.
 799          *
 800          * @throws DBUnexpectedError
 801          * @return string
 802          */
 803         public function makeList( $a, $mode = LIST_COMMA, $binaryColumns = [] ) {
 804                 if ( !is_array( $a ) ) {
 805                         throw new DBUnexpectedError( $this, __METHOD__ . ' called with incorrect parameters' );
 806                 }
 807
 808                 if ( $mode != LIST_NAMES ) {
 809                         // In MS SQL, values need to be specially encoded when they are
 810                         // inserted into binary fields. Perform this necessary encoding
 811                         // for the specified set of columns.
 812                         foreach ( array_keys( $a ) as $field ) {
 813                                 if ( !isset( $binaryColumns[$field] ) ) {
 814                                         continue;
 815                                 }
 816
 817                                 if ( is_array( $a[$field] ) ) {
 818                                         foreach ( $a[$field] as &$v ) {
 819                                                 $v = new MssqlBlob( $v );
 820                                         }
 821                                         unset( $v );
 822                                 } else {
 823                                         $a[$field] = new MssqlBlob( $a[$field] );
 824                                 }
 825                         }
 826                 }
 827
 828                 return parent::makeList( $a, $mode );
 829         }
 830
 831         /**
 832          * @param string $table
 833          * @param string $field
 834          * @return int Returns the size of a text field, or -1 for "unlimited"
 835          */
 836         public function textFieldSize( $table, $field ) {
 837                 $table = $this->tableName( $table );
 838                 $sql = "SELECT CHARACTER_MAXIMUM_LENGTH,DATA_TYPE FROM INFORMATION_SCHEMA.Columns
 839                         WHERE TABLE_NAME = '$table' AND COLUMN_NAME = '$field'";
 840                 $res = $this->query( $sql );
 841                 $row = $this->fetchRow( $res );
 842                 $size = -1;
 843                 if ( strtolower( $row['DATA_TYPE'] ) != 'text' ) {
 844                         $size = $row['CHARACTER_MAXIMUM_LENGTH'];
 845                 }
 846
 847                 return $size;
 848         }
 849
 850         /**
 851          * Construct a LIMIT query with optional offset
 852          * This is used for query pages
 853          *
 854          * @param string $sql SQL query we will append the limit too
 855          * @param int $limit The SQL limit
 856          * @param bool|int $offset The SQL offset (default false)
 857          * @return array|string
 858          * @throws DBUnexpectedError
 859          */
 860         public function limitResult( $sql, $limit, $offset = false ) {
 861                 if ( $offset === false || $offset == 0 ) {
 862                         if ( strpos( $sql, "SELECT" ) === false ) {
 863                                 return "TOP {$limit} " . $sql;
 864                         } else {
 865                                 return preg_replace( '/\bSELECT(\s+DISTINCT)?\b/Dsi',
 866                                         'SELECT$1 TOP ' . $limit, $sql, 1 );
 867                         }
 868                 } else {
 869                         // This one is fun, we need to pull out the select list as well as any ORDER BY clause
 870                         $select = $orderby = [];
 871                         $s1 = preg_match( '#SELECT\s+(.+?)\s+FROM#Dis', $sql, $select );
 872                         $s2 = preg_match( '#(ORDER BY\s+.+?)(\s*FOR XML .*)?$#Dis', $sql, $orderby );
 873                         $postOrder = '';
 874                         $first = $offset + 1;
 875                         $last = $offset + $limit;
 876                         $sub1 = 'sub_' . $this->mSubqueryId;
 877                         $sub2 = 'sub_' . ( $this->mSubqueryId + 1 );
 878                         $this->mSubqueryId += 2;
 879                         if ( !$s1 ) {
 880                                 // wat
 881                                 throw new DBUnexpectedError( $this, "Attempting to LIMIT a non-SELECT query\n" );
 882                         }
 883                         if ( !$s2 ) {
 884                                 // no ORDER BY
 885                                 $overOrder = 'ORDER BY (SELECT 1)';
 886                         } else {
 887                                 if ( !isset( $orderby[2] ) || !$orderby[2] ) {
 888                                         // don't need to strip it out if we're using a FOR XML clause
 889                                         $sql = str_replace( $orderby[1], '', $sql );
 890                                 }
 891                                 $overOrder = $orderby[1];
 892                                 $postOrder = ' ' . $overOrder;
 893                         }
 894                         $sql = "SELECT {$select[1]}
 895                                         FROM (
 896                                                 SELECT ROW_NUMBER() OVER({$overOrder}) AS rowNumber, *
 897                                                 FROM ({$sql}) {$sub1}
 898                                         ) {$sub2}
 899                                         WHERE rowNumber BETWEEN {$first} AND {$last}{$postOrder}";
 900
 901                         return $sql;
 902                 }
 903         }
 904
 905         /**
 906          * If there is a limit clause, parse it, strip it, and pass the remaining
 907          * SQL through limitResult() with the appropriate parameters. Not the
 908          * prettiest solution, but better than building a whole new parser. This
 909          * exists becase there are still too many extensions that don't use dynamic
 910          * sql generation.
 911          *
 912          * @param string $sql
 913          * @return array|mixed|string
 914          */
 915         public function LimitToTopN( $sql ) {
 916                 // Matches: LIMIT {[offset,] row_count | row_count OFFSET offset}
 917                 $pattern = '/\bLIMIT\s+((([0-9]+)\s*,\s*)?([0-9]+)(\s+OFFSET\s+([0-9]+))?)/i';
 918                 if ( preg_match( $pattern, $sql, $matches ) ) {
 919                         $row_count = $matches[4];
 920                         $offset = $matches[3] ?: $matches[6] ?: false;
 921
 922                         // strip the matching LIMIT clause out
 923                         $sql = str_replace( $matches[0], '', $sql );
 924
 925                         return $this->limitResult( $sql, $row_count, $offset );
 926                 }
 927
 928                 return $sql;
 929         }
 930
 931         /**
 932          * @return string Wikitext of a link to the server software's web site
 933          */
 934         public function getSoftwareLink() {
 935                 return "[{{int:version-db-mssql-url}} MS SQL Server]";
 936         }
 937
 938         /**
 939          * @return string Version information from the database
 940          */
 941         public function getServerVersion() {
 942                 $server_info = sqlsrv_server_info( $this->mConn );
 943                 $version = 'Error';
 944                 if ( isset( $server_info['SQLServerVersion'] ) ) {
 945                         $version = $server_info['SQLServerVersion'];
 946                 }
 947
 948                 return $version;
 949         }
 950
 951         /**
 952          * @param string $table
 953          * @param string $fname
 954          * @return bool
 955          */
 956         public function tableExists( $table, $fname = __METHOD__ ) {
 957                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
 958
 959                 if ( $db !== false ) {
 960                         // remote database
 961                         $this->queryLogger->error( "Attempting to call tableExists on a remote table" );
 962                         return false;
 963                 }
 964
 965                 if ( $schema === false ) {
 966                         $schema = $this->mSchema;
 967                 }
 968
 969                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.TABLES
 970                         WHERE TABLE_TYPE = 'BASE TABLE'
 971                         AND TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table'" );
 972
 973                 if ( $res->numRows() ) {
 974                         return true;
 975                 } else {
 976                         return false;
 977                 }
 978         }
 979
 980         /**
 981          * Query whether a given column exists in the mediawiki schema
 982          * @param string $table
 983          * @param string $field
 984          * @param string $fname
 985          * @return bool
 986          */
 987         public function fieldExists( $table, $field, $fname = __METHOD__ ) {
 988                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
 989
 990                 if ( $db !== false ) {
 991                         // remote database
 992                         $this->queryLogger->error( "Attempting to call fieldExists on a remote table" );
 993                         return false;
 994                 }
 995
 996                 $res = $this->query( "SELECT 1 FROM INFORMATION_SCHEMA.COLUMNS
 997                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
 998
 999                 if ( $res->numRows() ) {
1000                         return true;
1001                 } else {
1002                         return false;
1003                 }
1004         }
1005
1006         public function fieldInfo( $table, $field ) {
1007                 list( $db, $schema, $table ) = $this->tableName( $table, 'split' );
1008
1009                 if ( $db !== false ) {
1010                         // remote database
1011                         $this->queryLogger->error( "Attempting to call fieldInfo on a remote table" );
1012                         return false;
1013                 }
1014
1015                 $res = $this->query( "SELECT * FROM INFORMATION_SCHEMA.COLUMNS
1016                         WHERE TABLE_SCHEMA = '$schema' AND TABLE_NAME = '$table' AND COLUMN_NAME = '$field'" );
1017
1018                 $meta = $res->fetchRow();
1019                 if ( $meta ) {
1020                         return new MssqlField( $meta );
1021                 }
1022
1023                 return false;
1024         }
1025
1026         /**
1027          * Begin a transaction, committing any previously open transaction
1028          * @param string $fname
1029          */
1030         protected function doBegin( $fname = __METHOD__ ) {
1031                 sqlsrv_begin_transaction( $this->mConn );
1032                 $this->mTrxLevel = 1;
1033         }
1034
1035         /**
1036          * End a transaction
1037          * @param string $fname
1038          */
1039         protected function doCommit( $fname = __METHOD__ ) {
1040                 sqlsrv_commit( $this->mConn );
1041                 $this->mTrxLevel = 0;
1042         }
1043
1044         /**
1045          * Rollback a transaction.
1046          * No-op on non-transactional databases.
1047          * @param string $fname
1048          */
1049         protected function doRollback( $fname = __METHOD__ ) {
1050                 sqlsrv_rollback( $this->mConn );
1051                 $this->mTrxLevel = 0;
1052         }
1053
1054         /**
1055          * @param string $s
1056          * @return string
1057          */
1058         public function strencode( $s ) {
1059                 // Should not be called by us
1060
1061                 return str_replace( "'", "''", $s );
1062         }
1063
1064         /**
1065          * @param string|int|null|bool|Blob $s
1066          * @return string|int
1067          */
1068         public function addQuotes( $s ) {
1069                 if ( $s instanceof MssqlBlob ) {
1070                         return $s->fetch();
1071                 } elseif ( $s instanceof Blob ) {
1072                         // this shouldn't really ever be called, but it's here if needed
1073                         // (and will quite possibly make the SQL error out)
1074                         $blob = new MssqlBlob( $s->fetch() );
1075                         return $blob->fetch();
1076                 } else {
1077                         if ( is_bool( $s ) ) {
1078                                 $s = $s ? 1 : 0;
1079                         }
1080                         return parent::addQuotes( $s );
1081                 }
1082         }
1083
1084         /**
1085          * @param string $s
1086          * @return string
1087          */
1088         public function addIdentifierQuotes( $s ) {
1089                 // http://msdn.microsoft.com/en-us/library/aa223962.aspx
1090                 return '[' . $s . ']';
1091         }
1092
1093         /**
1094          * @param string $name
1095          * @return bool
1096          */
1097         public function isQuotedIdentifier( $name ) {
1098                 return strlen( $name ) && $name[0] == '[' && substr( $name, -1, 1 ) == ']';
1099         }
1100
1101         /**
1102          * MS SQL supports more pattern operators than other databases (ex: [,],^)
1103          *
1104          * @param string $s
1105          * @return string
1106          */
1107         protected function escapeLikeInternal( $s ) {
1108                 return addcslashes( $s, '\%_[]^' );
1109         }
1110
1111         /**
1112          * MS SQL requires specifying the escape character used in a LIKE query
1113          * or using Square brackets to surround characters that are to be escaped
1114          * https://msdn.microsoft.com/en-us/library/ms179859.aspx
1115          * Here we take the Specify-Escape-Character approach since it's less
1116          * invasive, renders a query that is closer to other DB's and better at
1117          * handling square bracket escaping
1118          *
1119          * @return string Fully built LIKE statement
1120          */
1121         public function buildLike() {
1122                 $params = func_get_args();
1123                 if ( count( $params ) > 0 && is_array( $params[0] ) ) {
1124                         $params = $params[0];
1125                 }
1126
1127                 return parent::buildLike( $params ) . " ESCAPE '\' ";
1128         }
1129
1130         /**
1131          * @param string $db
1132          * @return bool
1133          */
1134         public function selectDB( $db ) {
1135                 try {
1136                         $this->mDBname = $db;
1137                         $this->query( "USE $db" );
1138                         return true;
1139                 } catch ( Exception $e ) {
1140                         return false;
1141                 }
1142         }
1143
1144         /**
1145          * @param array $options An associative array of options to be turned into
1146          *   an SQL query, valid keys are listed in the function.
1147          * @return array
1148          */
1149         public function makeSelectOptions( $options ) {
1150                 $tailOpts = '';
1151                 $startOpts = '';
1152
1153                 $noKeyOptions = [];
1154                 foreach ( $options as $key => $option ) {
1155                         if ( is_numeric( $key ) ) {
1156                                 $noKeyOptions[$option] = true;
1157                         }
1158                 }
1159
1160                 $tailOpts .= $this->makeGroupByWithHaving( $options );
1161
1162                 $tailOpts .= $this->makeOrderBy( $options );
1163
1164                 if ( isset( $noKeyOptions['DISTINCT'] ) || isset( $noKeyOptions['DISTINCTROW'] ) ) {
1165                         $startOpts .= 'DISTINCT';
1166                 }
1167
1168                 if ( isset( $noKeyOptions['FOR XML'] ) ) {
1169                         // used in group concat field emulation
1170                         $tailOpts .= " FOR XML PATH('')";
1171                 }
1172
1173                 // we want this to be compatible with the output of parent::makeSelectOptions()
1174                 return [ $startOpts, '', $tailOpts, '', '' ];
1175         }
1176
1177         public function getType() {
1178                 return 'mssql';
1179         }
1180
1181         /**
1182          * @param array $stringList
1183          * @return string
1184          */
1185         public function buildConcat( $stringList ) {
1186                 return implode( ' + ', $stringList );
1187         }
1188
1189         /**
1190          * Build a GROUP_CONCAT or equivalent statement for a query.
1191          * MS SQL doesn't have GROUP_CONCAT so we emulate it with other stuff (and boy is it nasty)
1192          *
1193          * This is useful for combining a field for several rows into a single string.
1194          * NULL values will not appear in the output, duplicated values will appear,
1195          * and the resulting delimiter-separated values have no defined sort order.
1196          * Code using the results may need to use the PHP unique() or sort() methods.
1197          *
1198          * @param string $delim Glue to bind the results together
1199          * @param string|array $table Table name
1200          * @param string $field Field name
1201          * @param string|array $conds Conditions
1202          * @param string|array $join_conds Join conditions
1203          * @return string SQL text
1204          * @since 1.23
1205          */
1206         public function buildGroupConcatField( $delim, $table, $field, $conds = '',
1207                 $join_conds = []
1208         ) {
1209                 $gcsq = 'gcsq_' . $this->mSubqueryId;
1210                 $this->mSubqueryId++;
1211
1212                 $delimLen = strlen( $delim );
1213                 $fld = "{$field} + {$this->addQuotes( $delim )}";
1214                 $sql = "(SELECT LEFT({$field}, LEN({$field}) - {$delimLen}) FROM ("
1215                         . $this->selectSQLText( $table, $fld, $conds, null, [ 'FOR XML' ], $join_conds )
1216                         . ") {$gcsq} ({$field}))";
1217
1218                 return $sql;
1219         }
1220
1221         /**
1222          * Returns an associative array for fields that are of type varbinary, binary, or image
1223          * $table can be either a raw table name or passed through tableName() first
1224          * @param string $table
1225          * @return array
1226          */
1227         private function getBinaryColumns( $table ) {
1228                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1229                 $tableRaw = array_pop( $tableRawArr );
1230
1231                 if ( $this->mBinaryColumnCache === null ) {
1232                         $this->populateColumnCaches();
1233                 }
1234
1235                 return isset( $this->mBinaryColumnCache[$tableRaw] )
1236                         ? $this->mBinaryColumnCache[$tableRaw]
1237                         : [];
1238         }
1239
1240         /**
1241          * @param string $table
1242          * @return array
1243          */
1244         private function getBitColumns( $table ) {
1245                 $tableRawArr = explode( '.', preg_replace( '#\[([^\]]*)\]#', '$1', $table ) );
1246                 $tableRaw = array_pop( $tableRawArr );
1247
1248                 if ( $this->mBitColumnCache === null ) {
1249                         $this->populateColumnCaches();
1250                 }
1251
1252                 return isset( $this->mBitColumnCache[$tableRaw] )
1253                         ? $this->mBitColumnCache[$tableRaw]
1254                         : [];
1255         }
1256
1257         private function populateColumnCaches() {
1258                 $res = $this->select( 'INFORMATION_SCHEMA.COLUMNS', '*',
1259                         [
1260                                 'TABLE_CATALOG' => $this->mDBname,
1261                                 'TABLE_SCHEMA' => $this->mSchema,
1262                                 'DATA_TYPE' => [ 'varbinary', 'binary', 'image', 'bit' ]
1263                         ] );
1264
1265                 $this->mBinaryColumnCache = [];
1266                 $this->mBitColumnCache = [];
1267                 foreach ( $res as $row ) {
1268                         if ( $row->DATA_TYPE == 'bit' ) {
1269                                 $this->mBitColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1270                         } else {
1271                                 $this->mBinaryColumnCache[$row->TABLE_NAME][$row->COLUMN_NAME] = $row;
1272                         }
1273                 }
1274         }
1275
1276         /**
1277          * @param string $name
1278          * @param string $format
1279          * @return string
1280          */
1281         function tableName( $name, $format = 'quoted' ) {
1282                 # Replace reserved words with better ones
1283                 switch ( $name ) {
1284                         case 'user':
1285                                 return $this->realTableName( 'mwuser', $format );
1286                         default:
1287                                 return $this->realTableName( $name, $format );
1288                 }
1289         }
1290
1291         /**
1292          * call this instead of tableName() in the updater when renaming tables
1293          * @param string $name
1294          * @param string $format One of quoted, raw, or split
1295          * @return string
1296          */
1297         function realTableName( $name, $format = 'quoted' ) {
1298                 $table = parent::tableName( $name, $format );
1299                 if ( $format == 'split' ) {
1300                         // Used internally, we want the schema split off from the table name and returned
1301                         // as a list with 3 elements (database, schema, table)
1302                         $table = explode( '.', $table );
1303                         while ( count( $table ) < 3 ) {
1304                                 array_unshift( $table, false );
1305                         }
1306                 }
1307                 return $table;
1308         }
1309
1310         /**
1311          * Delete a table
1312          * @param string $tableName
1313          * @param string $fName
1314          * @return bool|ResultWrapper
1315          * @since 1.18
1316          */
1317         public function dropTable( $tableName, $fName = __METHOD__ ) {
1318                 if ( !$this->tableExists( $tableName, $fName ) ) {
1319                         return false;
1320                 }
1321
1322                 // parent function incorrectly appends CASCADE, which we don't want
1323                 $sql = "DROP TABLE " . $this->tableName( $tableName );
1324
1325                 return $this->query( $sql, $fName );
1326         }
1327
1328         /**
1329          * Called in the installer and updater.
1330          * Probably doesn't need to be called anywhere else in the codebase.
1331          * @param bool|null $value
1332          * @return bool|null
1333          */
1334         public function prepareStatements( $value = null ) {
1335                 $old = $this->mPrepareStatements;
1336                 if ( $value !== null ) {
1337                         $this->mPrepareStatements = $value;
1338                 }
1339
1340                 return $old;
1341         }
1342
1343         /**
1344          * Called in the installer and updater.
1345          * Probably doesn't need to be called anywhere else in the codebase.
1346          * @param bool|null $value
1347          * @return bool|null
1348          */
1349         public function scrollableCursor( $value = null ) {
1350                 $old = $this->mScrollableCursor;
1351                 if ( $value !== null ) {
1352                         $this->mScrollableCursor = $value;
1353                 }
1354
1355                 return $old;
1356         }
1357 }