includes/db/DatabaseIbm_db2.php

   1 <?php
   2 /**
   3  * This is the IBM DB2 database abstraction layer.
   4  * See maintenance/ibm_db2/README for development notes
   5  * and other specific information
   6  *
   7  * @file
   8  * @ingroup Database
   9  * @author leo.petr+mediawiki@gmail.com
  10  */
  11
  12 /**
  13  * This represents a column in a DB2 database
  14  * @ingroup Database
  15  */
  16 class IBM_DB2Field {
  17         private $name = '';
  18         private $tablename = '';
  19         private $type = '';
  20         private $nullable = false;
  21         private $max_length = 0;
  22
  23         /**
  24          * Builder method for the class
  25          * @param $db DatabaseIbm_db2: Database interface
  26          * @param $table String: table name
  27          * @param $field String: column name
  28          * @return IBM_DB2Field
  29          */
  30         static function fromText( $db, $table, $field ) {
  31                 global $wgDBmwschema;
  32
  33                 $q = <<<SQL
  34 SELECT
  35 lcase( coltype ) AS typname,
  36 nulls AS attnotnull, length AS attlen
  37 FROM sysibm.syscolumns
  38 WHERE tbcreator=%s AND tbname=%s AND name=%s;
  39 SQL;
  40                 $res = $db->query(
  41                         sprintf( $q,
  42                                 $db->addQuotes( $wgDBmwschema ),
  43                                 $db->addQuotes( $table ),
  44                                 $db->addQuotes( $field )
  45                         )
  46                 );
  47                 $row = $db->fetchObject( $res );
  48                 if ( !$row ) {
  49                         return null;
  50                 }
  51                 $n = new IBM_DB2Field;
  52                 $n->type = $row->typname;
  53                 $n->nullable = ( $row->attnotnull == 'N' );
  54                 $n->name = $field;
  55                 $n->tablename = $table;
  56                 $n->max_length = $row->attlen;
  57                 return $n;
  58         }
  59         /**
  60          * Get column name
  61          * @return string column name
  62          */
  63         function name() { return $this->name; }
  64         /**
  65          * Get table name
  66          * @return string table name
  67          */
  68         function tableName() { return $this->tablename; }
  69         /**
  70          * Get column type
  71          * @return string column type
  72          */
  73         function type() { return $this->type; }
  74         /**
  75          * Can column be null?
  76          * @return bool true or false
  77          */
  78         function nullable() { return $this->nullable; }
  79         /**
  80          * How much can you fit in the column per row?
  81          * @return int length
  82          */
  83         function maxLength() { return $this->max_length; }
  84 }
  85
  86 /**
  87  * Wrapper around binary large objects
  88  * @ingroup Database
  89  */
  90 class IBM_DB2Blob {
  91         private $mData;
  92
  93         public function __construct( $data ) {
  94                 $this->mData = $data;
  95         }
  96
  97         public function getData() {
  98                 return $this->mData;
  99         }
 100
 101         public function __toString() {
 102                 return $this->mData;
 103         }
 104 }
 105
 106 /**
 107  * Primary database interface
 108  * @ingroup Database
 109  */
 110 class DatabaseIbm_db2 extends DatabaseBase {
 111         /*
 112          * Inherited members
 113         protected $mLastQuery = '';
 114         protected $mPHPError = false;
 115
 116         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
 117         protected $mOut, $mOpened = false;
 118
 119         protected $mFailFunction;
 120         protected $mTablePrefix;
 121         protected $mFlags;
 122         protected $mTrxLevel = 0;
 123         protected $mErrorCount = 0;
 124         protected $mLBInfo = array();
 125         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 126          *
 127          */
 128
 129         /** Database server port */
 130         protected $mPort = null;
 131         /** Schema for tables, stored procedures, triggers */
 132         protected $mSchema = null;
 133         /** Whether the schema has been applied in this session */
 134         protected $mSchemaSet = false;
 135         /** Result of last query */
 136         protected $mLastResult = null;
 137         /** Number of rows affected by last INSERT/UPDATE/DELETE */
 138         protected $mAffectedRows = null;
 139         /** Number of rows returned by last SELECT */
 140         protected $mNumRows = null;
 141
 142         /** Connection config options - see constructor */
 143         public $mConnOptions = array();
 144         /** Statement config options -- see constructor */
 145         public $mStmtOptions = array();
 146
 147         /** Default schema */
 148         const USE_GLOBAL = 'mediawiki';
 149
 150         /** Option that applies to nothing */
 151         const NONE_OPTION = 0x00;
 152         /** Option that applies to connection objects */
 153         const CONN_OPTION = 0x01;
 154         /** Option that applies to statement objects */
 155         const STMT_OPTION = 0x02;
 156
 157         /** Regular operation mode -- minimal debug messages */
 158         const REGULAR_MODE = 'regular';
 159         /** Installation mode -- lots of debug messages */
 160         const INSTALL_MODE = 'install';
 161
 162         /** Controls the level of debug message output */
 163         protected $mMode = self::REGULAR_MODE;
 164
 165         /** Last sequence value used for a primary key */
 166         protected $mInsertId = null;
 167
 168         ######################################
 169         # Getters and Setters
 170         ######################################
 171
 172         /**
 173          * Returns true if this database supports (and uses) cascading deletes
 174          */
 175         function cascadingDeletes() {
 176                 return true;
 177         }
 178
 179         /**
 180          * Returns true if this database supports (and uses) triggers (e.g. on the
 181          *  page table)
 182          */
 183         function cleanupTriggers() {
 184                 return true;
 185         }
 186
 187         /**
 188          * Returns true if this database is strict about what can be put into an
 189          *  IP field.
 190          * Specifically, it uses a NULL value instead of an empty string.
 191          */
 192         function strictIPs() {
 193                 return true;
 194         }
 195
 196         /**
 197          * Returns true if this database uses timestamps rather than integers
 198         */
 199         function realTimestamps() {
 200                 return true;
 201         }
 202
 203         /**
 204          * Returns true if this database does an implicit sort when doing GROUP BY
 205          */
 206         function implicitGroupby() {
 207                 return false;
 208         }
 209
 210         /**
 211          * Returns true if this database does an implicit order by when the column
 212          *  has an index
 213          * For example: SELECT page_title FROM page LIMIT 1
 214          */
 215         function implicitOrderby() {
 216                 return false;
 217         }
 218
 219         /**
 220          * Returns true if this database can do a native search on IP columns
 221          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 222          */
 223         function searchableIPs() {
 224                 return true;
 225         }
 226
 227         /**
 228          * Returns true if this database can use functional indexes
 229          */
 230         function functionalIndexes() {
 231                 return true;
 232         }
 233
 234         /**
 235          * Returns a unique string representing the wiki on the server
 236          */
 237         function getWikiID() {
 238                 if( $this->mSchema ) {
 239                         return "{$this->mDBname}-{$this->mSchema}";
 240                 } else {
 241                         return $this->mDBname;
 242                 }
 243         }
 244
 245         function getType() {
 246                 return 'ibm_db2';
 247         }
 248
 249         ######################################
 250         # Setup
 251         ######################################
 252
 253
 254         /**
 255          *
 256          * @param $server String: hostname of database server
 257          * @param $user String: username
 258          * @param $password String: password
 259          * @param $dbName String: database name on the server
 260          * @param $failFunction Callback (optional)
 261          * @param $flags Integer: database behaviour flags (optional, unused)
 262          * @param $schema String
 263          */
 264         public function DatabaseIbm_db2( $server = false, $user = false,
 265                                                         $password = false,
 266                                                         $dbName = false, $failFunction = false, $flags = 0,
 267                                                         $schema = self::USE_GLOBAL )
 268         {
 269
 270                 global $wgOut, $wgDBmwschema;
 271                 # Can't get a reference if it hasn't been set yet
 272                 if ( !isset( $wgOut ) ) {
 273                         $wgOut = null;
 274                 }
 275                 $this->mOut =& $wgOut;
 276                 $this->mFlags = DBO_TRX | $flags;
 277
 278                 if ( $schema == self::USE_GLOBAL ) {
 279                         $this->mSchema = $wgDBmwschema;
 280                 } else {
 281                         $this->mSchema = $schema;
 282                 }
 283
 284                 // configure the connection and statement objects
 285                 $this->setDB2Option( 'db2_attr_case', 'DB2_CASE_LOWER',
 286                         self::CONN_OPTION | self::STMT_OPTION );
 287                 $this->setDB2Option( 'deferred_prepare', 'DB2_DEFERRED_PREPARE_ON',
 288                         self::STMT_OPTION );
 289                 $this->setDB2Option( 'rowcount', 'DB2_ROWCOUNT_PREFETCH_ON',
 290                         self::STMT_OPTION );
 291
 292                 $this->open( $server, $user, $password, $dbName );
 293         }
 294
 295         /**
 296          * Enables options only if the ibm_db2 extension version supports them
 297          * @param $name String: name of the option in the options array
 298          * @param $const String: name of the constant holding the right option value
 299          * @param $type Integer: whether this is a Connection or Statement otion
 300          */
 301         private function setDB2Option( $name, $const, $type ) {
 302                 if ( defined( $const ) ) {
 303                         if ( $type & self::CONN_OPTION ) {
 304                                 $this->mConnOptions[$name] = constant( $const );
 305                         }
 306                         if ( $type & self::STMT_OPTION ) {
 307                                 $this->mStmtOptions[$name] = constant( $const );
 308                         }
 309                 } else {
 310                         $this->installPrint(
 311                                 "$const is not defined. ibm_db2 version is likely too low." );
 312                 }
 313         }
 314
 315         /**
 316          * Outputs debug information in the appropriate place
 317          * @param $string String: the relevant debug message
 318          */
 319         private function installPrint( $string ) {
 320                 wfDebug( "$string\n" );
 321                 if ( $this->mMode == self::INSTALL_MODE ) {
 322                         print "<li><pre>$string</pre></li>";
 323                         flush();
 324                 }
 325         }
 326
 327         /**
 328          * Opens a database connection and returns it
 329          * Closes any existing connection
 330          *
 331          * @param $server String: hostname
 332          * @param $user String
 333          * @param $password String
 334          * @param $dbName String: database name
 335          * @return a fresh connection
 336          */
 337         public function open( $server, $user, $password, $dbName ) {
 338                 // Load the port number
 339                 global $wgDBport;
 340                 wfProfileIn( __METHOD__ );
 341
 342                 // Load IBM DB2 driver if missing
 343                 wfDl( 'ibm_db2' );
 344
 345                 // Test for IBM DB2 support, to avoid suppressed fatal error
 346                 if ( !function_exists( 'db2_connect' ) ) {
 347                         $error = <<<ERROR
 348 DB2 functions missing, have you enabled the ibm_db2 extension for PHP?
 349
 350 ERROR;
 351                         $this->installPrint( $error );
 352                         $this->reportConnectionError( $error );
 353                 }
 354
 355                 if ( strlen( $user ) < 1 ) {
 356                         return null;
 357                 }
 358
 359                 // Close existing connection
 360                 $this->close();
 361                 // Cache conn info
 362                 $this->mServer = $server;
 363                 $this->mPort = $port = $wgDBport;
 364                 $this->mUser = $user;
 365                 $this->mPassword = $password;
 366                 $this->mDBname = $dbName;
 367
 368                 $this->openUncataloged( $dbName, $user, $password, $server, $port );
 369
 370                 // Apply connection config
 371                 db2_set_option( $this->mConn, $this->mConnOptions, 1 );
 372                 // Some MediaWiki code is still transaction-less (?).
 373                 // The strategy is to keep AutoCommit on for that code
 374                 //  but switch it off whenever a transaction is begun.
 375                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 376
 377                 if ( !$this->mConn ) {
 378                         $this->installPrint( "DB connection error\n" );
 379                         $this->installPrint(
 380                                 "Server: $server, Database: $dbName, User: $user, Password: "
 381                                 . substr( $password, 0, 3 ) . "...\n" );
 382                         $this->installPrint( $this->lastError() . "\n" );
 383                         return null;
 384                 }
 385
 386                 $this->mOpened = true;
 387                 $this->applySchema();
 388
 389                 wfProfileOut( __METHOD__ );
 390                 return $this->mConn;
 391         }
 392
 393         /**
 394          * Opens a cataloged database connection, sets mConn
 395          */
 396         protected function openCataloged( $dbName, $user, $password ) {
 397                 @$this->mConn = db2_pconnect( $dbName, $user, $password );
 398         }
 399
 400         /**
 401          * Opens an uncataloged database connection, sets mConn
 402          */
 403         protected function openUncataloged( $dbName, $user, $password, $server, $port )
 404         {
 405                 $str = "DRIVER={IBM DB2 ODBC DRIVER};";
 406                 $str .= "DATABASE=$dbName;";
 407                 $str .= "HOSTNAME=$server;";
 408                 // port was formerly validated to not be 0
 409                 $str .= "PORT=$port;";
 410                 $str .= "PROTOCOL=TCPIP;";
 411                 $str .= "UID=$user;";
 412                 $str .= "PWD=$password;";
 413
 414                 @$this->mConn = db2_pconnect( $str, $user, $password );
 415         }
 416
 417         /**
 418          * Closes a database connection, if it is open
 419          * Returns success, true if already closed
 420          */
 421         public function close() {
 422                 $this->mOpened = false;
 423                 if ( $this->mConn ) {
 424                         if ( $this->trxLevel() > 0 ) {
 425                                 $this->commit();
 426                         }
 427                         return db2_close( $this->mConn );
 428                 } else {
 429                         return true;
 430                 }
 431         }
 432
 433         /**
 434          * Returns a fresh instance of this class
 435          *
 436          * @param $server String: hostname of database server
 437          * @param $user String: username
 438          * @param $password String
 439          * @param $dbName String: database name on the server
 440          * @param $failFunction Callback (optional)
 441          * @param $flags Integer: database behaviour flags (optional, unused)
 442          * @return DatabaseIbm_db2 object
 443          */
 444         static function newFromParams( $server, $user, $password, $dbName,
 445                 $failFunction = false, $flags = 0 )
 446         {
 447                 return new DatabaseIbm_db2( $server, $user, $password, $dbName,
 448                         $failFunction, $flags );
 449         }
 450
 451         /**
 452          * Retrieves the most current database error
 453          * Forces a database rollback
 454          */
 455         public function lastError() {
 456                 $connerr = db2_conn_errormsg();
 457                 if ( $connerr ) {
 458                         //$this->rollback();
 459                         return $connerr;
 460                 }
 461                 $stmterr = db2_stmt_errormsg();
 462                 if ( $stmterr ) {
 463                         //$this->rollback();
 464                         return $stmterr;
 465                 }
 466
 467                 return false;
 468         }
 469
 470         /**
 471          * Get the last error number
 472          * Return 0 if no error
 473          * @return integer
 474          */
 475         public function lastErrno() {
 476                 $connerr = db2_conn_error();
 477                 if ( $connerr ) {
 478                         return $connerr;
 479                 }
 480                 $stmterr = db2_stmt_error();
 481                 if ( $stmterr ) {
 482                         return $stmterr;
 483                 }
 484                 return 0;
 485         }
 486
 487         /**
 488          * Is a database connection open?
 489          * @return
 490          */
 491         public function isOpen() { return $this->mOpened; }
 492
 493         /**
 494          * The DBMS-dependent part of query()
 495          * @param  $sql String: SQL query.
 496          * @return object Result object for fetch functions or false on failure
 497          * @access private
 498          */
 499         /*private*/
 500         public function doQuery( $sql ) {
 501                 $this->applySchema();
 502
 503                 $ret = db2_exec( $this->mConn, $sql, $this->mStmtOptions );
 504                 if( $ret == false ) {
 505                         $error = db2_stmt_errormsg();
 506                         $this->installPrint( "<pre>$sql</pre>" );
 507                         $this->installPrint( $error );
 508                         throw new DBUnexpectedError( $this, 'SQL error: '
 509                                 . htmlspecialchars( $error ) );
 510                 }
 511                 $this->mLastResult = $ret;
 512                 $this->mAffectedRows = null; // Not calculated until asked for
 513                 return $ret;
 514         }
 515
 516         /**
 517          * @return string Version information from the database
 518          */
 519         public function getServerVersion() {
 520                 $info = db2_server_info( $this->mConn );
 521                 return $info->DBMS_VER;
 522         }
 523
 524         /**
 525          * Queries whether a given table exists
 526          * @return boolean
 527          */
 528         public function tableExists( $table ) {
 529                 $schema = $this->mSchema;
 530                 $sql = <<< EOF
 531 SELECT COUNT( * ) FROM SYSIBM.SYSTABLES ST
 532 WHERE ST.NAME = '$table' AND ST.CREATOR = '$schema'
 533 EOF;
 534                 $res = $this->query( $sql );
 535                 if ( !$res ) {
 536                         return false;
 537                 }
 538
 539                 // If the table exists, there should be one of it
 540                 @$row = $this->fetchRow( $res );
 541                 $count = $row[0];
 542                 if ( $count == '1' || $count == 1 ) {
 543                         return true;
 544                 }
 545
 546                 return false;
 547         }
 548
 549         /**
 550          * Fetch the next row from the given result object, in object form.
 551          * Fields can be retrieved with $row->fieldname, with fields acting like
 552          * member variables.
 553          *
 554          * @param $res SQL result object as returned from Database::query(), etc.
 555          * @return DB2 row object
 556          * @throws DBUnexpectedError Thrown if the database returns an error
 557          */
 558         public function fetchObject( $res ) {
 559                 if ( $res instanceof ResultWrapper ) {
 560                         $res = $res->result;
 561                 }
 562                 @$row = db2_fetch_object( $res );
 563                 if( $this->lastErrno() ) {
 564                         throw new DBUnexpectedError( $this, 'Error in fetchObject(): '
 565                                 . htmlspecialchars( $this->lastError() ) );
 566                 }
 567                 return $row;
 568         }
 569
 570         /**
 571          * Fetch the next row from the given result object, in associative array
 572          * form. Fields are retrieved with $row['fieldname'].
 573          *
 574          * @param $res SQL result object as returned from Database::query(), etc.
 575          * @return DB2 row object
 576          * @throws DBUnexpectedError Thrown if the database returns an error
 577          */
 578         public function fetchRow( $res ) {
 579                 if ( $res instanceof ResultWrapper ) {
 580                         $res = $res->result;
 581                 }
 582                 @$row = db2_fetch_array( $res );
 583                 if ( $this->lastErrno() ) {
 584                         throw new DBUnexpectedError( $this, 'Error in fetchRow(): '
 585                                 . htmlspecialchars( $this->lastError() ) );
 586                 }
 587                 return $row;
 588         }
 589
 590         /**
 591          * Create tables, stored procedures, and so on
 592          */
 593         public function setup_database() {
 594                 try {
 595                         // TODO: switch to root login if available
 596
 597                         // Switch into the correct namespace
 598                         $this->applySchema();
 599                         $this->begin();
 600
 601                         $res = $this->sourceFile( "../maintenance/ibm_db2/tables.sql" );
 602                         if ( $res !== true ) {
 603                                 print ' <b>FAILED</b>: ' . htmlspecialchars( $res ) . '</li>';
 604                         } else {
 605                                 print ' done</li>';
 606                         }
 607                         $res = $this->sourceFile( "../maintenance/ibm_db2/foreignkeys.sql" );
 608                         if ( $res !== true ) {
 609                                 print ' <b>FAILED</b>: ' . htmlspecialchars( $res ) . '</li>';
 610                         } else {
 611                                 print '<li>Foreign keys done</li>';
 612                         }
 613                         $res = null;
 614
 615                         // TODO: populate interwiki links
 616
 617                         if ( $this->lastError() ) {
 618                                 $this->installPrint(
 619                                         'Errors encountered during table creation -- rolled back' );
 620                                 $this->installPrint( 'Please install again' );
 621                                 $this->rollback();
 622                         } else {
 623                                 $this->commit();
 624                         }
 625                 } catch ( MWException $mwe ) {
 626                         print "<br><pre>$mwe</pre><br>";
 627                 }
 628         }
 629
 630         /**
 631          * Escapes strings
 632          * Doesn't escape numbers
 633          *
 634          * @param $s String: string to escape
 635          * @return escaped string
 636          */
 637         public function addQuotes( $s ) {
 638                 //$this->installPrint( "DB2::addQuotes( $s )\n" );
 639                 if ( is_null( $s ) ) {
 640                         return 'NULL';
 641                 } elseif ( $s instanceof Blob ) {
 642                         return "'" . $s->fetch( $s ) . "'";
 643                 } elseif ( $s instanceof IBM_DB2Blob ) {
 644                         return "'" . $this->decodeBlob( $s ) . "'";
 645                 }
 646                 $s = $this->strencode( $s );
 647                 if ( is_numeric( $s ) ) {
 648                         return $s;
 649                 } else {
 650                         return "'$s'";
 651                 }
 652         }
 653
 654         /**
 655          * Verifies that a DB2 column/field type is numeric
 656          *
 657          * @param $type String: DB2 column type
 658          * @return Boolean: true if numeric
 659          */
 660         public function is_numeric_type( $type ) {
 661                 switch ( strtoupper( $type ) ) {
 662                         case 'SMALLINT':
 663                         case 'INTEGER':
 664                         case 'INT':
 665                         case 'BIGINT':
 666                         case 'DECIMAL':
 667                         case 'REAL':
 668                         case 'DOUBLE':
 669                         case 'DECFLOAT':
 670                                 return true;
 671                 }
 672                 return false;
 673         }
 674
 675         /**
 676          * Alias for addQuotes()
 677          * @param $s String: string to escape
 678          * @return escaped string
 679          */
 680         public function strencode( $s ) {
 681                 // Bloody useless function
 682                 //  Prepends backslashes to \x00, \n, \r, \, ', " and \x1a.
 683                 //  But also necessary
 684                 $s = db2_escape_string( $s );
 685                 // Wide characters are evil -- some of them look like '
 686                 $s = utf8_encode( $s );
 687                 // Fix its stupidity
 688                 $from = array(  "\\\\", "\\'",  '\\n',  '\\t',  '\\"',  '\\r' );
 689                 $to = array(            "\\",           "''",           "\n",           "\t",           '"',            "\r" );
 690                 $s = str_replace( $from, $to, $s ); // DB2 expects '', not \' escaping
 691                 return $s;
 692         }
 693
 694         /**
 695          * Switch into the database schema
 696          */
 697         protected function applySchema() {
 698                 if ( !( $this->mSchemaSet ) ) {
 699                         $this->mSchemaSet = true;
 700                         $this->begin();
 701                         $this->doQuery( "SET SCHEMA = $this->mSchema" );
 702                         $this->commit();
 703                 }
 704         }
 705
 706         /**
 707          * Start a transaction (mandatory)
 708          */
 709         public function begin( $fname = 'DatabaseIbm_db2::begin' ) {
 710                 // BEGIN is implicit for DB2
 711                 // However, it requires that AutoCommit be off.
 712
 713                 // Some MediaWiki code is still transaction-less (?).
 714                 // The strategy is to keep AutoCommit on for that code
 715                 //  but switch it off whenever a transaction is begun.
 716                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_OFF );
 717
 718                 $this->mTrxLevel = 1;
 719         }
 720
 721         /**
 722          * End a transaction
 723          * Must have a preceding begin()
 724          */
 725         public function commit( $fname = 'DatabaseIbm_db2::commit' ) {
 726                 db2_commit( $this->mConn );
 727
 728                 // Some MediaWiki code is still transaction-less (?).
 729                 // The strategy is to keep AutoCommit on for that code
 730                 //  but switch it off whenever a transaction is begun.
 731                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 732
 733                 $this->mTrxLevel = 0;
 734         }
 735
 736         /**
 737          * Cancel a transaction
 738          */
 739         public function rollback( $fname = 'DatabaseIbm_db2::rollback' ) {
 740                 db2_rollback( $this->mConn );
 741                 // turn auto-commit back on
 742                 // not sure if this is appropriate
 743                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 744                 $this->mTrxLevel = 0;
 745         }
 746
 747         /**
 748          * Makes an encoded list of strings from an array
 749          * $mode:
 750          *   LIST_COMMA         - comma separated, no field names
 751          *   LIST_AND           - ANDed WHERE clause (without the WHERE)
 752          *   LIST_OR            - ORed WHERE clause (without the WHERE)
 753          *   LIST_SET           - comma separated with field names, like a SET clause
 754          *   LIST_NAMES         - comma separated field names
 755          *   LIST_SET_PREPARED  - like LIST_SET, except with ? tokens as values
 756          */
 757         function makeList( $a, $mode = LIST_COMMA ) {
 758                 if ( !is_array( $a ) ) {
 759                         throw new DBUnexpectedError( $this,
 760                                 'DatabaseBase::makeList called with incorrect parameters' );
 761                 }
 762
 763                 // if this is for a prepared UPDATE statement
 764                 // (this should be promoted to the parent class
 765                 //  once other databases use prepared statements)
 766                 if ( $mode == LIST_SET_PREPARED ) {
 767                         $first = true;
 768                         $list = '';
 769                         foreach ( $a as $field => $value ) {
 770                                 if ( !$first ) {
 771                                         $list .= ", $field = ?";
 772                                 } else {
 773                                         $list .= "$field = ?";
 774                                         $first = false;
 775                                 }
 776                         }
 777                         $list .= '';
 778
 779                         return $list;
 780                 }
 781
 782                 // otherwise, call the usual function
 783                 return parent::makeList( $a, $mode );
 784         }
 785
 786         /**
 787          * Construct a LIMIT query with optional offset
 788          * This is used for query pages
 789          *
 790          * @param $sql string SQL query we will append the limit too
 791          * @param $limit integer the SQL limit
 792          * @param $offset integer the SQL offset (default false)
 793          */
 794         public function limitResult( $sql, $limit, $offset=false ) {
 795                 if( !is_numeric( $limit ) ) {
 796                         throw new DBUnexpectedError( $this,
 797                                 "Invalid non-numeric limit passed to limitResult()\n" );
 798                 }
 799                 if( $offset ) {
 800                         if ( stripos( $sql, 'where' ) === false ) {
 801                                 return "$sql AND ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 802                         } else {
 803                                 return "$sql WHERE ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 804                         }
 805                 }
 806                 return "$sql FETCH FIRST $limit ROWS ONLY ";
 807         }
 808
 809         /**
 810          * Handle reserved keyword replacement in table names
 811          *
 812          * @param $name Object
 813          * @return String
 814          */
 815         public function tableName( $name ) {
 816                 // we want maximum compatibility with MySQL schema
 817                 return $name;
 818         }
 819
 820         /**
 821          * Generates a timestamp in an insertable format
 822          *
 823          * @param $ts timestamp
 824          * @return String: timestamp value
 825          */
 826         public function timestamp( $ts = 0 ) {
 827                 // TS_MW cannot be easily distinguished from an integer
 828                 return wfTimestamp( TS_DB2, $ts );
 829         }
 830
 831         /**
 832          * Return the next in a sequence, save the value for retrieval via insertId()
 833          * @param $seqName String: name of a defined sequence in the database
 834          * @return next value in that sequence
 835          */
 836         public function nextSequenceValue( $seqName ) {
 837                 // Not using sequences in the primary schema to allow for easier migration
 838                 //  from MySQL
 839                 // Emulating MySQL behaviour of using NULL to signal that sequences
 840                 // aren't used
 841                 /*
 842                 $safeseq = preg_replace( "/'/", "''", $seqName );
 843                 $res = $this->query( "VALUES NEXTVAL FOR $safeseq" );
 844                 $row = $this->fetchRow( $res );
 845                 $this->mInsertId = $row[0];
 846                 return $this->mInsertId;
 847                 */
 848                 return null;
 849         }
 850
 851         /**
 852          * This must be called after nextSequenceVal
 853          * @return Last sequence value used as a primary key
 854          */
 855         public function insertId() {
 856                 return $this->mInsertId;
 857         }
 858
 859         /**
 860          * Updates the mInsertId property with the value of the last insert
 861          *  into a generated column
 862          *
 863          * @param $table      String: sanitized table name
 864          * @param $primaryKey Mixed: string name of the primary key
 865          * @param $stmt       Resource: prepared statement resource
 866          *  of the SELECT primary_key FROM FINAL TABLE ( INSERT ... ) form
 867          */
 868         private function calcInsertId( $table, $primaryKey, $stmt ) {
 869                 if ( $primaryKey ) {
 870                         $this->mInsertId = db2_last_insert_id( $this->mConn );
 871                 }
 872         }
 873
 874         /**
 875          * INSERT wrapper, inserts an array into a table
 876          *
 877          * $args may be a single associative array, or an array of arrays
 878          *  with numeric keys, for multi-row insert
 879          *
 880          * @param $table   String: Name of the table to insert to.
 881          * @param $args    Array: Items to insert into the table.
 882          * @param $fname   String: Name of the function, for profiling
 883          * @param $options String or Array. Valid options: IGNORE
 884          *
 885          * @return bool Success of insert operation. IGNORE always returns true.
 886          */
 887         public function insert( $table, $args, $fname = 'DatabaseIbm_db2::insert',
 888                 $options = array() )
 889         {
 890                 if ( !count( $args ) ) {
 891                         return true;
 892                 }
 893                 // get database-specific table name (not used)
 894                 $table = $this->tableName( $table );
 895                 // format options as an array
 896                 $options = IBM_DB2Helper::makeArray( $options );
 897                 // format args as an array of arrays
 898                 if ( !( isset( $args[0] ) && is_array( $args[0] ) ) ) {
 899                         $args = array( $args );
 900                 }
 901
 902                 // prevent insertion of NULL into primary key columns
 903                 list( $args, $primaryKeys ) = $this->removeNullPrimaryKeys( $table, $args );
 904                 // if there's only one primary key
 905                 // we'll be able to read its value after insertion
 906                 $primaryKey = false;
 907                 if ( count( $primaryKeys ) == 1 ) {
 908                         $primaryKey = $primaryKeys[0];
 909                 }
 910
 911                 // get column names
 912                 $keys = array_keys( $args[0] );
 913                 $key_count = count( $keys );
 914
 915                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 916                 $ignore = in_array( 'IGNORE', $options ) ? 'mw' : '';
 917
 918                 // assume success
 919                 $res = true;
 920                 // If we are not in a transaction, we need to be for savepoint trickery
 921                 if ( !$this->mTrxLevel ) {
 922                         $this->begin();
 923                 }
 924
 925                 $sql = "INSERT INTO $table ( " . implode( ',', $keys ) . ' ) VALUES ';
 926                 if ( $key_count == 1 ) {
 927                         $sql .= '( ? )';
 928                 } else {
 929                         $sql .= '( ?' . str_repeat( ',?', $key_count-1 ) . ' )';
 930                 }
 931                 //$this->installPrint( "Preparing the following SQL:" );
 932                 //$this->installPrint( "$sql" );
 933                 //$this->installPrint( print_r( $args, true ));
 934                 $stmt = $this->prepare( $sql );
 935
 936                 // start a transaction/enter transaction mode
 937                 $this->begin();
 938
 939                 if ( !$ignore ) {
 940                         //$first = true;
 941                         foreach ( $args as $row ) {
 942                                 //$this->installPrint( "Inserting " . print_r( $row, true ));
 943                                 // insert each row into the database
 944                                 $res = $res & $this->execute( $stmt, $row );
 945                                 if ( !$res ) {
 946                                         $this->installPrint( 'Last error:' );
 947                                         $this->installPrint( $this->lastError() );
 948                                 }
 949                                 // get the last inserted value into a generated column
 950                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 951                         }
 952                 } else {
 953                         $olde = error_reporting( 0 );
 954                         // For future use, we may want to track the number of actual inserts
 955                         // Right now, insert (all writes) simply return true/false
 956                         $numrowsinserted = 0;
 957
 958                         // always return true
 959                         $res = true;
 960
 961                         foreach ( $args as $row ) {
 962                                 $overhead = "SAVEPOINT $ignore ON ROLLBACK RETAIN CURSORS";
 963                                 db2_exec( $this->mConn, $overhead, $this->mStmtOptions );
 964
 965                                 $this->execute( $stmt, $row );
 966
 967                                 if ( !$res2 ) {
 968                                         $this->installPrint( 'Last error:' );
 969                                         $this->installPrint( $this->lastError() );
 970                                 }
 971                                 // get the last inserted value into a generated column
 972                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 973
 974                                 $errNum = $this->lastErrno();
 975                                 if ( $errNum ) {
 976                                         db2_exec( $this->mConn, "ROLLBACK TO SAVEPOINT $ignore",
 977                                                 $this->mStmtOptions );
 978                                 } else {
 979                                         db2_exec( $this->mConn, "RELEASE SAVEPOINT $ignore",
 980                                                 $this->mStmtOptions );
 981                                         $numrowsinserted++;
 982                                 }
 983                         }
 984
 985                         $olde = error_reporting( $olde );
 986                         // Set the affected row count for the whole operation
 987                         $this->mAffectedRows = $numrowsinserted;
 988                 }
 989                 // commit either way
 990                 $this->commit();
 991                 $this->freePrepared( $stmt );
 992
 993                 return $res;
 994         }
 995
 996         /**
 997          * Given a table name and a hash of columns with values
 998          * Removes primary key columns from the hash where the value is NULL
 999          *
1000          * @param $table String: name of the table
1001          * @param $args Array of hashes of column names with values
1002          * @return Array: tuple( filtered array of columns, array of primary keys )
1003          */
1004         private function removeNullPrimaryKeys( $table, $args ) {
1005                 $schema = $this->mSchema;
1006                 // find out the primary keys
1007                 $keyres = db2_primary_keys( $this->mConn, null, strtoupper( $schema ),
1008                         strtoupper( $table )
1009                 );
1010                 $keys = array();
1011                 for (
1012                         $row = $this->fetchObject( $keyres );
1013                         $row != null;
1014                         $row = $this->fetchObject( $keyres )
1015                 )
1016                 {
1017                         $keys[] = strtolower( $row->column_name );
1018                 }
1019                 // remove primary keys
1020                 foreach ( $args as $ai => $row ) {
1021                         foreach ( $keys as $key ) {
1022                                 if ( $row[$key] == null ) {
1023                                         unset( $row[$key] );
1024                                 }
1025                         }
1026                         $args[$ai] = $row;
1027                 }
1028                 // return modified hash
1029                 return array( $args, $keys );
1030         }
1031
1032         /**
1033          * UPDATE wrapper, takes a condition array and a SET array
1034          *
1035          * @param $table  String: The table to UPDATE
1036          * @param $values An array of values to SET
1037          * @param $conds  An array of conditions ( WHERE ). Use '*' to update all rows.
1038          * @param $fname  String: The Class::Function calling this function
1039          *                ( for the log )
1040          * @param $options An array of UPDATE options, can be one or
1041          *                 more of IGNORE, LOW_PRIORITY
1042          * @return Boolean
1043          */
1044         public function update( $table, $values, $conds, $fname = 'Database::update',
1045                 $options = array() )
1046         {
1047                 $table = $this->tableName( $table );
1048                 $opts = $this->makeUpdateOptions( $options );
1049                 $sql = "UPDATE $opts $table SET "
1050                         . $this->makeList( $values, LIST_SET_PREPARED );
1051                 if ( $conds != '*' ) {
1052                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1053                 }
1054                 $stmt = $this->prepare( $sql );
1055                 $this->installPrint( 'UPDATE: ' . print_r( $values, true ) );
1056                 // assuming for now that an array with string keys will work
1057                 // if not, convert to simple array first
1058                 $result = $this->execute( $stmt, $values );
1059                 $this->freePrepared( $stmt );
1060
1061                 return $result;
1062         }
1063
1064         /**
1065          * DELETE query wrapper
1066          *
1067          * Use $conds == "*" to delete all rows
1068          */
1069         public function delete( $table, $conds, $fname = 'Database::delete' ) {
1070                 if ( !$conds ) {
1071                         throw new DBUnexpectedError( $this,
1072                         'Database::delete() called with no conditions' );
1073                 }
1074                 $table = $this->tableName( $table );
1075                 $sql = "DELETE FROM $table";
1076                 if ( $conds != '*' ) {
1077                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1078                 }
1079                 $result = $this->query( $sql, $fname );
1080
1081                 return $result;
1082         }
1083
1084         /**
1085          * Returns the number of rows affected by the last query or 0
1086          * @return Integer: the number of rows affected by the last query
1087          */
1088         public function affectedRows() {
1089                 if ( !is_null( $this->mAffectedRows ) ) {
1090                         // Forced result for simulated queries
1091                         return $this->mAffectedRows;
1092                 }
1093                 if( empty( $this->mLastResult ) ) {
1094                         return 0;
1095                 }
1096                 return db2_num_rows( $this->mLastResult );
1097         }
1098
1099         /**
1100          * Simulates REPLACE with a DELETE followed by INSERT
1101          * @param $table Object
1102          * @param $uniqueIndexes Array consisting of indexes and arrays of indexes
1103          * @param $rows Array: rows to insert
1104          * @param $fname String: name of the function for profiling
1105          * @return nothing
1106          */
1107         function replace( $table, $uniqueIndexes, $rows,
1108                 $fname = 'DatabaseIbm_db2::replace' )
1109         {
1110                 $table = $this->tableName( $table );
1111
1112                 if ( count( $rows )==0 ) {
1113                         return;
1114                 }
1115
1116                 # Single row case
1117                 if ( !is_array( reset( $rows ) ) ) {
1118                         $rows = array( $rows );
1119                 }
1120
1121                 foreach( $rows as $row ) {
1122                         # Delete rows which collide
1123                         if ( $uniqueIndexes ) {
1124                                 $sql = "DELETE FROM $table WHERE ";
1125                                 $first = true;
1126                                 foreach ( $uniqueIndexes as $index ) {
1127                                         if ( $first ) {
1128                                                 $first = false;
1129                                                 $sql .= '( ';
1130                                         } else {
1131                                                 $sql .= ' ) OR ( ';
1132                                         }
1133                                         if ( is_array( $index ) ) {
1134                                                 $first2 = true;
1135                                                 foreach ( $index as $col ) {
1136                                                         if ( $first2 ) {
1137                                                                 $first2 = false;
1138                                                         } else {
1139                                                                 $sql .= ' AND ';
1140                                                         }
1141                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
1142                                                 }
1143                                         } else {
1144                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
1145                                         }
1146                                 }
1147                                 $sql .= ' )';
1148                                 $this->query( $sql, $fname );
1149                         }
1150
1151                         # Now insert the row
1152                         $sql = "INSERT INTO $table ( "
1153                                 . $this->makeList( array_keys( $row ), LIST_NAMES )
1154                                 .' ) VALUES ( ' . $this->makeList( $row, LIST_COMMA ) . ' )';
1155                         $this->query( $sql, $fname );
1156                 }
1157         }
1158
1159         /**
1160          * Returns the number of rows in the result set
1161          * Has to be called right after the corresponding select query
1162          * @param $res Object result set
1163          * @return Integer: number of rows
1164          */
1165         public function numRows( $res ) {
1166                 if ( $res instanceof ResultWrapper ) {
1167                         $res = $res->result;
1168                 }
1169                 if ( $this->mNumRows ) {
1170                         return $this->mNumRows;
1171                 } else {
1172                         return 0;
1173                 }
1174         }
1175
1176         /**
1177          * Moves the row pointer of the result set
1178          * @param $res Object: result set
1179          * @param $row Integer: row number
1180          * @return success or failure
1181          */
1182         public function dataSeek( $res, $row ) {
1183                 if ( $res instanceof ResultWrapper ) {
1184                         $res = $res->result;
1185                 }
1186                 return db2_fetch_row( $res, $row );
1187         }
1188
1189         ###
1190         # Fix notices in Block.php
1191         ###
1192
1193         /**
1194          * Frees memory associated with a statement resource
1195          * @param $res Object: statement resource to free
1196          * @return Boolean success or failure
1197          */
1198         public function freeResult( $res ) {
1199                 if ( $res instanceof ResultWrapper ) {
1200                         $res = $res->result;
1201                 }
1202                 if ( !@db2_free_result( $res ) ) {
1203                         throw new DBUnexpectedError( $this, "Unable to free DB2 result\n" );
1204                 }
1205         }
1206
1207         /**
1208          * Returns the number of columns in a resource
1209          * @param $res Object: statement resource
1210          * @return Number of fields/columns in resource
1211          */
1212         public function numFields( $res ) {
1213                 if ( $res instanceof ResultWrapper ) {
1214                         $res = $res->result;
1215                 }
1216                 return db2_num_fields( $res );
1217         }
1218
1219         /**
1220          * Returns the nth column name
1221          * @param $res Object: statement resource
1222          * @param $n Integer: Index of field or column
1223          * @return String name of nth column
1224          */
1225         public function fieldName( $res, $n ) {
1226                 if ( $res instanceof ResultWrapper ) {
1227                         $res = $res->result;
1228                 }
1229                 return db2_field_name( $res, $n );
1230         }
1231
1232         /**
1233          * SELECT wrapper
1234          *
1235          * @param $table   Array or string, table name(s) (prefix auto-added)
1236          * @param $vars    Array or string, field name(s) to be retrieved
1237          * @param $conds   Array or string, condition(s) for WHERE
1238          * @param $fname   String: calling function name (use __METHOD__)
1239          *                 for logs/profiling
1240          * @param $options Associative array of options
1241          *                 (e.g. array('GROUP BY' => 'page_title')),
1242          *                 see Database::makeSelectOptions code for list of
1243          *                 supported stuff
1244          * @param $join_conds Associative array of table join conditions (optional)
1245          *                    (e.g. array( 'page' => array('LEFT JOIN',
1246          *                    'page_latest=rev_id') )
1247          * @return Mixed: database result resource for fetch functions or false
1248          *                 on failure
1249          */
1250         public function select( $table, $vars, $conds = '', $fname = 'DatabaseIbm_db2::select', $options = array(), $join_conds = array() )
1251         {
1252                 $res = parent::select( $table, $vars, $conds, $fname, $options,
1253                         $join_conds );
1254
1255                 // We must adjust for offset
1256                 if ( isset( $options['LIMIT'] ) ) {
1257                         if ( isset ( $options['OFFSET'] ) ) {
1258                                 $limit = $options['LIMIT'];
1259                                 $offset = $options['OFFSET'];
1260                         }
1261                 }
1262
1263                 // DB2 does not have a proper num_rows() function yet, so we must emulate
1264                 // DB2 9.5.4 and the corresponding ibm_db2 driver will introduce
1265                 //  a working one
1266                 // TODO: Yay!
1267
1268                 // we want the count
1269                 $vars2 = array( 'count( * ) as num_rows' );
1270                 // respecting just the limit option
1271                 $options2 = array();
1272                 if ( isset( $options['LIMIT'] ) ) {
1273                         $options2['LIMIT'] = $options['LIMIT'];
1274                 }
1275                 // but don't try to emulate for GROUP BY
1276                 if ( isset( $options['GROUP BY'] ) ) {
1277                         return $res;
1278                 }
1279
1280                 $res2 = parent::select( $table, $vars2, $conds, $fname, $options2,
1281                         $join_conds );
1282                 $obj = $this->fetchObject( $res2 );
1283                 $this->mNumRows = $obj->num_rows;
1284
1285                 return $res;
1286         }
1287
1288         /**
1289          * Handles ordering, grouping, and having options ('GROUP BY' => colname)
1290          * Has limited support for per-column options (colnum => 'DISTINCT')
1291          *
1292          * @private
1293          *
1294          * @param $options Associative array of options to be turned into
1295          *              an SQL query, valid keys are listed in the function.
1296          * @return Array
1297          */
1298         function makeSelectOptions( $options ) {
1299                 $preLimitTail = $postLimitTail = '';
1300                 $startOpts = '';
1301
1302                 $noKeyOptions = array();
1303                 foreach ( $options as $key => $option ) {
1304                         if ( is_numeric( $key ) ) {
1305                                 $noKeyOptions[$option] = true;
1306                         }
1307                 }
1308
1309                 if ( isset( $options['GROUP BY'] ) ) {
1310                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
1311                 }
1312                 if ( isset( $options['HAVING'] ) ) {
1313                         $preLimitTail .= " HAVING {$options['HAVING']}";
1314                 }
1315                 if ( isset( $options['ORDER BY'] ) ) {
1316                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
1317                 }
1318
1319                 if ( isset( $noKeyOptions['DISTINCT'] )
1320                         || isset( $noKeyOptions['DISTINCTROW'] ) )
1321                 {
1322                         $startOpts .= 'DISTINCT';
1323                 }
1324
1325                 return array( $startOpts, '', $preLimitTail, $postLimitTail );
1326         }
1327
1328         /**
1329          * Returns link to IBM DB2 free download
1330          * @return String: wikitext of a link to the server software's web site
1331          */
1332         public static function getSoftwareLink() {
1333                 return '[http://www.ibm.com/db2/express/ IBM DB2]';
1334         }
1335
1336         /**
1337          * Get search engine class. All subclasses of this
1338          * need to implement this if they wish to use searching.
1339          *
1340          * @return String
1341          */
1342         public function getSearchEngine() {
1343                 return 'SearchIBM_DB2';
1344         }
1345
1346         /**
1347          * Did the last database access fail because of deadlock?
1348          * @return Boolean
1349          */
1350         public function wasDeadlock() {
1351                 // get SQLSTATE
1352                 $err = $this->lastErrno();
1353                 switch( $err ) {
1354                         // This is literal port of the MySQL logic and may be wrong for DB2
1355                         case '40001':   // sql0911n, Deadlock or timeout, rollback
1356                         case '57011':   // sql0904n, Resource unavailable, no rollback
1357                         case '57033':   // sql0913n, Deadlock or timeout, no rollback
1358                         $this->installPrint( "In a deadlock because of SQLSTATE $err" );
1359                         return true;
1360                 }
1361                 return false;
1362         }
1363
1364         /**
1365          * Ping the server and try to reconnect if it there is no connection
1366          * The connection may be closed and reopened while this happens
1367          * @return Boolean: whether the connection exists
1368          */
1369         public function ping() {
1370                 // db2_ping() doesn't exist
1371                 // Emulate
1372                 $this->close();
1373                 $this->mConn = $this->openUncataloged( $this->mDBName, $this->mUser,
1374                         $this->mPassword, $this->mServer, $this->mPort );
1375
1376                 return false;
1377         }
1378         ######################################
1379         # Unimplemented and not applicable
1380         ######################################
1381         /**
1382          * Not implemented
1383          * @return string ''
1384          */
1385         public function getStatus( $which = '%' ) {
1386                 $this->installPrint( 'Not implemented for DB2: getStatus()' );
1387                 return '';
1388         }
1389         /**
1390          * Not implemented
1391          * @return string $sql
1392          */
1393         public function limitResultForUpdate( $sql, $num ) {
1394                 $this->installPrint( 'Not implemented for DB2: limitResultForUpdate()' );
1395                 return $sql;
1396         }
1397
1398         /**
1399          * Only useful with fake prepare like in base Database class
1400          * @return      string
1401          */
1402         public function fillPreparedArg( $matches ) {
1403                 $this->installPrint( 'Not useful for DB2: fillPreparedArg()' );
1404                 return '';
1405         }
1406
1407         ######################################
1408         # Reflection
1409         ######################################
1410
1411         /**
1412          * Returns information about an index
1413          * If errors are explicitly ignored, returns NULL on failure
1414          * @param $table String: table name
1415          * @param $index String: index name
1416          * @param $fname String: function name for logging and profiling
1417          * @return Object query row in object form
1418          */
1419         public function indexInfo( $table, $index,
1420                 $fname = 'DatabaseIbm_db2::indexExists' )
1421         {
1422                 $table = $this->tableName( $table );
1423                 $sql = <<<SQL
1424 SELECT name as indexname
1425 FROM sysibm.sysindexes si
1426 WHERE si.name='$index' AND si.tbname='$table'
1427 AND sc.tbcreator='$this->mSchema'
1428 SQL;
1429                 $res = $this->query( $sql, $fname );
1430                 if ( !$res ) {
1431                         return null;
1432                 }
1433                 $row = $this->fetchObject( $res );
1434                 if ( $row != null ) {
1435                         return $row;
1436                 } else {
1437                         return false;
1438                 }
1439         }
1440
1441         /**
1442          * Returns an information object on a table column
1443          * @param $table String: table name
1444          * @param $field String: column name
1445          * @return IBM_DB2Field
1446          */
1447         public function fieldInfo( $table, $field ) {
1448                 return IBM_DB2Field::fromText( $this, $table, $field );
1449         }
1450
1451         /**
1452          * db2_field_type() wrapper
1453          * @param $res Object: result of executed statement
1454          * @param $index Mixed: number or name of the column
1455          * @return String column type
1456          */
1457         public function fieldType( $res, $index ) {
1458                 if ( $res instanceof ResultWrapper ) {
1459                         $res = $res->result;
1460                 }
1461                 return db2_field_type( $res, $index );
1462         }
1463
1464         /**
1465          * Verifies that an index was created as unique
1466          * @param $table String: table name
1467          * @param $index String: index name
1468          * @param $fname function name for profiling
1469          * @return Bool
1470          */
1471         public function indexUnique ( $table, $index,
1472                 $fname = 'Database::indexUnique' )
1473         {
1474                 $table = $this->tableName( $table );
1475                 $sql = <<<SQL
1476 SELECT si.name as indexname
1477 FROM sysibm.sysindexes si
1478 WHERE si.name='$index' AND si.tbname='$table'
1479 AND sc.tbcreator='$this->mSchema'
1480 AND si.uniquerule IN ( 'U', 'P' )
1481 SQL;
1482                 $res = $this->query( $sql, $fname );
1483                 if ( !$res ) {
1484                         return null;
1485                 }
1486                 if ( $this->fetchObject( $res ) ) {
1487                         return true;
1488                 }
1489                 return false;
1490
1491         }
1492
1493         /**
1494          * Returns the size of a text field, or -1 for "unlimited"
1495          * @param $table String: table name
1496          * @param $field String: column name
1497          * @return Integer: length or -1 for unlimited
1498          */
1499         public function textFieldSize( $table, $field ) {
1500                 $table = $this->tableName( $table );
1501                 $sql = <<<SQL
1502 SELECT length as size
1503 FROM sysibm.syscolumns sc
1504 WHERE sc.name='$field' AND sc.tbname='$table'
1505 AND sc.tbcreator='$this->mSchema'
1506 SQL;
1507                 $res = $this->query( $sql );
1508                 $row = $this->fetchObject( $res );
1509                 $size = $row->size;
1510                 return $size;
1511         }
1512
1513         /**
1514          * DELETE where the condition is a join
1515          * @param $delTable String: deleting from this table
1516          * @param $joinTable String: using data from this table
1517          * @param $delVar String: variable in deleteable table
1518          * @param $joinVar String: variable in data table
1519          * @param $conds Array: conditionals for join table
1520          * @param $fname String: function name for profiling
1521          */
1522         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar,
1523                 $conds, $fname = "DatabaseIbm_db2::deleteJoin" )
1524         {
1525                 if ( !$conds ) {
1526                         throw new DBUnexpectedError( $this,
1527                         'Database::deleteJoin() called with empty $conds' );
1528                 }
1529
1530                 $delTable = $this->tableName( $delTable );
1531                 $joinTable = $this->tableName( $joinTable );
1532                 $sql = <<<SQL
1533 DELETE FROM $delTable
1534 WHERE $delVar IN (
1535   SELECT $joinVar FROM $joinTable
1536
1537 SQL;
1538                 if ( $conds != '*' ) {
1539                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
1540                 }
1541                 $sql .= ' )';
1542
1543                 $this->query( $sql, $fname );
1544         }
1545
1546         /**
1547          * Description is left as an exercise for the reader
1548          * @param $b Mixed: data to be encoded
1549          * @return IBM_DB2Blob
1550          */
1551         public function encodeBlob( $b ) {
1552                 return new IBM_DB2Blob( $b );
1553         }
1554
1555         /**
1556          * Description is left as an exercise for the reader
1557          * @param $b IBM_DB2Blob: data to be decoded
1558          * @return mixed
1559          */
1560         public function decodeBlob( $b ) {
1561                 return "$b";
1562         }
1563
1564         /**
1565          * Convert into a list of string being concatenated
1566          * @param $stringList Array: strings that need to be joined together
1567          *                    by the SQL engine
1568          * @return String: joined by the concatenation operator
1569          */
1570         public function buildConcat( $stringList ) {
1571                 // || is equivalent to CONCAT
1572                 // Sample query: VALUES 'foo' CONCAT 'bar' CONCAT 'baz'
1573                 return implode( ' || ', $stringList );
1574         }
1575
1576         /**
1577          * Generates the SQL required to convert a DB2 timestamp into a Unix epoch
1578          * @param $column String: name of timestamp column
1579          * @return String: SQL code
1580          */
1581         public function extractUnixEpoch( $column ) {
1582                 // TODO
1583                 // see SpecialAncientpages
1584         }
1585
1586         ######################################
1587         # Prepared statements
1588         ######################################
1589
1590         /**
1591          * Intended to be compatible with the PEAR::DB wrapper functions.
1592          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1593          *
1594          * ? = scalar value, quoted as necessary
1595          * ! = raw SQL bit (a function for instance)
1596          * & = filename; reads the file and inserts as a blob
1597          *     (we don't use this though...)
1598          * @param $sql String: SQL statement with appropriate markers
1599          * @param $func String: Name of the function, for profiling
1600          * @return resource a prepared DB2 SQL statement
1601          */
1602         public function prepare( $sql, $func = 'DB2::prepare' ) {
1603                 $stmt = db2_prepare( $this->mConn, $sql, $this->mStmtOptions );
1604                 return $stmt;
1605         }
1606
1607         /**
1608          * Frees resources associated with a prepared statement
1609          * @return Boolean success or failure
1610          */
1611         public function freePrepared( $prepared ) {
1612                 return db2_free_stmt( $prepared );
1613         }
1614
1615         /**
1616          * Execute a prepared query with the various arguments
1617          * @param $prepared String: the prepared sql
1618          * @param $args Mixed: either an array here, or put scalars as varargs
1619          * @return Resource: results object
1620          */
1621         public function execute( $prepared, $args = null ) {
1622                 if( !is_array( $args ) ) {
1623                         # Pull the var args
1624                         $args = func_get_args();
1625                         array_shift( $args );
1626                 }
1627                 $res = db2_execute( $prepared, $args );
1628                 if ( !$res ) {
1629                         $this->installPrint( db2_stmt_errormsg() );
1630                 }
1631                 return $res;
1632         }
1633
1634         /**
1635          * Prepare & execute an SQL statement, quoting and inserting arguments
1636          * in the appropriate places.
1637          * @param $query String
1638          * @param $args ...
1639          */
1640         public function safeQuery( $query, $args = null ) {
1641                 // copied verbatim from Database.php
1642                 $prepared = $this->prepare( $query, 'DB2::safeQuery' );
1643                 if( !is_array( $args ) ) {
1644                         # Pull the var args
1645                         $args = func_get_args();
1646                         array_shift( $args );
1647                 }
1648                 $retval = $this->execute( $prepared, $args );
1649                 $this->freePrepared( $prepared );
1650                 return $retval;
1651         }
1652
1653         /**
1654          * For faking prepared SQL statements on DBs that don't support
1655          * it directly.
1656          * @param $preparedQuery String: a 'preparable' SQL statement
1657          * @param $args Array of arguments to fill it with
1658          * @return String: executable statement
1659          */
1660         public function fillPrepared( $preparedQuery, $args ) {
1661                 reset( $args );
1662                 $this->preparedArgs =& $args;
1663
1664                 foreach ( $args as $i => $arg ) {
1665                         db2_bind_param( $preparedQuery, $i+1, $args[$i] );
1666                 }
1667
1668                 return $preparedQuery;
1669         }
1670
1671         /**
1672          * Switches module between regular and install modes
1673          */
1674         public function setMode( $mode ) {
1675                 $old = $this->mMode;
1676                 $this->mMode = $mode;
1677                 return $old;
1678         }
1679
1680         /**
1681          * Bitwise negation of a column or value in SQL
1682          * Same as (~field) in C
1683          * @param $field String
1684          * @return String
1685          */
1686         function bitNot( $field ) {
1687                 // expecting bit-fields smaller than 4bytes
1688                 return "BITNOT( $field )";
1689         }
1690
1691         /**
1692          * Bitwise AND of two columns or values in SQL
1693          * Same as (fieldLeft & fieldRight) in C
1694          * @param $fieldLeft String
1695          * @param $fieldRight String
1696          * @return String
1697          */
1698         function bitAnd( $fieldLeft, $fieldRight ) {
1699                 return "BITAND( $fieldLeft, $fieldRight )";
1700         }
1701
1702         /**
1703          * Bitwise OR of two columns or values in SQL
1704          * Same as (fieldLeft | fieldRight) in C
1705          * @param $fieldLeft String
1706          * @param $fieldRight String
1707          * @return String
1708          */
1709         function bitOr( $fieldLeft, $fieldRight ) {
1710                 return "BITOR( $fieldLeft, $fieldRight )";
1711         }
1712 }
1713
1714 class IBM_DB2Helper {
1715         public static function makeArray( $maybeArray ) {
1716                 if ( !is_array( $maybeArray ) ) {
1717                         return array( $maybeArray );
1718                 }
1719
1720                 return $maybeArray;
1721         }
1722 }