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( sprintf( $q,
  41                                 $db->addQuotes( $wgDBmwschema ),
  42                                 $db->addQuotes( $table ),
  43                                 $db->addQuotes( $field )) );
  44                 $row = $db->fetchObject( $res );
  45                 if ( !$row )
  46                         return null;
  47                 $n = new IBM_DB2Field;
  48                 $n->type = $row->typname;
  49                 $n->nullable = ( $row->attnotnull == 'N' );
  50                 $n->name = $field;
  51                 $n->tablename = $table;
  52                 $n->max_length = $row->attlen;
  53                 return $n;
  54         }
  55         /**
  56          * Get column name
  57          * @return string column name
  58          */
  59         function name() { return $this->name; }
  60         /**
  61          * Get table name
  62          * @return string table name
  63          */
  64         function tableName() { return $this->tablename; }
  65         /**
  66          * Get column type
  67          * @return string column type
  68          */
  69         function type() { return $this->type; }
  70         /**
  71          * Can column be null?
  72          * @return bool true or false
  73          */
  74         function nullable() { return $this->nullable; }
  75         /**
  76          * How much can you fit in the column per row?
  77          * @return int length
  78          */
  79         function maxLength() { return $this->max_length; }
  80 }
  81
  82 /**
  83  * Wrapper around binary large objects
  84  * @ingroup Database
  85  */
  86 class IBM_DB2Blob {
  87         private $mData;
  88
  89         public function __construct( $data ) {
  90                 $this->mData = $data;
  91         }
  92
  93         public function getData() {
  94                 return $this->mData;
  95         }
  96
  97         public function __toString()
  98     {
  99         return $this->mData;
 100     }
 101 }
 102
 103 /**
 104  * Primary database interface
 105  * @ingroup Database
 106  */
 107 class DatabaseIbm_db2 extends DatabaseBase {
 108         /*
 109          * Inherited members
 110         protected $mLastQuery = '';
 111         protected $mPHPError = false;
 112
 113         protected $mServer, $mUser, $mPassword, $mConn = null, $mDBname;
 114         protected $mOut, $mOpened = false;
 115
 116         protected $mFailFunction;
 117         protected $mTablePrefix;
 118         protected $mFlags;
 119         protected $mTrxLevel = 0;
 120         protected $mErrorCount = 0;
 121         protected $mLBInfo = array();
 122         protected $mFakeSlaveLag = null, $mFakeMaster = false;
 123          *
 124          */
 125
 126         /** Database server port */
 127         protected $mPort = null;
 128         /** Schema for tables, stored procedures, triggers */
 129         protected $mSchema = null;
 130         /** Whether the schema has been applied in this session */
 131         protected $mSchemaSet = false;
 132         /** Result of last query */
 133         protected $mLastResult = null;
 134         /** Number of rows affected by last INSERT/UPDATE/DELETE */
 135         protected $mAffectedRows = null;
 136         /** Number of rows returned by last SELECT */
 137         protected $mNumRows = null;
 138
 139         /** Connection config options - see constructor */
 140         public $mConnOptions = array();
 141         /** Statement config options -- see constructor */
 142         public $mStmtOptions = array();
 143
 144         /** Default schema */
 145         const USE_GLOBAL = "mediawiki";
 146
 147         /** Option that applies to nothing */
 148         const NONE_OPTION = 0x00;
 149         /** Option that applies to connection objects */
 150         const CONN_OPTION = 0x01;
 151         /** Option that applies to statement objects */
 152         const STMT_OPTION = 0x02;
 153
 154         /** Regular operation mode -- minimal debug messages */
 155         const REGULAR_MODE = 'regular';
 156         /** Installation mode -- lots of debug messages */
 157         const INSTALL_MODE = 'install';
 158
 159         /** Controls the level of debug message output */
 160         protected $mMode = self::REGULAR_MODE;
 161
 162         /** Last sequence value used for a primary key */
 163         protected $mInsertId = null;
 164
 165         ######################################
 166         # Getters and Setters
 167         ######################################
 168
 169         /**
 170          * Returns true if this database supports (and uses) cascading deletes
 171          */
 172         function cascadingDeletes() {
 173                 return true;
 174         }
 175
 176         /**
 177          * Returns true if this database supports (and uses) triggers (e.g. on the
 178          *  page table)
 179          */
 180         function cleanupTriggers() {
 181                 return true;
 182         }
 183
 184         /**
 185          * Returns true if this database is strict about what can be put into an
 186          *  IP field.
 187          * Specifically, it uses a NULL value instead of an empty string.
 188          */
 189         function strictIPs() {
 190                 return true;
 191         }
 192
 193         /**
 194          * Returns true if this database uses timestamps rather than integers
 195         */
 196         function realTimestamps() {
 197                 return true;
 198         }
 199
 200         /**
 201          * Returns true if this database does an implicit sort when doing GROUP BY
 202          */
 203         function implicitGroupby() {
 204                 return false;
 205         }
 206
 207         /**
 208          * Returns true if this database does an implicit order by when the column
 209          *  has an index
 210          * For example: SELECT page_title FROM page LIMIT 1
 211          */
 212         function implicitOrderby() {
 213                 return false;
 214         }
 215
 216         /**
 217          * Returns true if this database can do a native search on IP columns
 218          * e.g. this works as expected: .. WHERE rc_ip = '127.42.12.102/32';
 219          */
 220         function searchableIPs() {
 221                 return true;
 222         }
 223
 224         /**
 225          * Returns true if this database can use functional indexes
 226          */
 227         function functionalIndexes() {
 228                 return true;
 229         }
 230
 231         /**
 232          * Returns a unique string representing the wiki on the server
 233          */
 234         function getWikiID() {
 235                 if( $this->mSchema ) {
 236                         return "{$this->mDBname}-{$this->mSchema}";
 237                 } else {
 238                         return $this->mDBname;
 239                 }
 240         }
 241
 242         function getType() {
 243                 return 'ibm_db2';
 244         }
 245
 246         ######################################
 247         # Setup
 248         ######################################
 249
 250
 251         /**
 252          *
 253          * @param $server String: hostname of database server
 254          * @param $user String: username
 255          * @param $password String: password
 256          * @param $dbName String: database name on the server
 257          * @param $failFunction Callback (optional)
 258          * @param $flags Integer: database behaviour flags (optional, unused)
 259          * @param $schema String
 260          */
 261         public function DatabaseIbm_db2( $server = false, $user = false,
 262                                                         $password = false,
 263                                                         $dbName = false, $failFunction = false, $flags = 0,
 264                                                         $schema = self::USE_GLOBAL )
 265         {
 266
 267                 global $wgOut, $wgDBmwschema;
 268                 # Can't get a reference if it hasn't been set yet
 269                 if ( !isset( $wgOut ) ) {
 270                         $wgOut = null;
 271                 }
 272                 $this->mOut =& $wgOut;
 273                 $this->mFailFunction = $failFunction;
 274                 $this->mFlags = DBO_TRX | $flags;
 275
 276                 if ( $schema == self::USE_GLOBAL ) {
 277                         $this->mSchema = $wgDBmwschema;
 278                 }
 279                 else {
 280                         $this->mSchema = $schema;
 281                 }
 282
 283                 // configure the connection and statement objects
 284                 $this->setDB2Option( 'db2_attr_case', 'DB2_CASE_LOWER',
 285                         self::CONN_OPTION | self::STMT_OPTION );
 286                 $this->setDB2Option( 'deferred_prepare', 'DB2_DEFERRED_PREPARE_ON',
 287                         self::STMT_OPTION );
 288                 $this->setDB2Option( 'rowcount', 'DB2_ROWCOUNT_PREFETCH_ON',
 289                         self::STMT_OPTION );
 290
 291                 $this->open( $server, $user, $password, $dbName );
 292         }
 293
 294         /**
 295          * Enables options only if the ibm_db2 extension version supports them
 296          * @param $name String: name of the option in the options array
 297          * @param $const String: name of the constant holding the right option value
 298          * @param $type Integer: whether this is a Connection or Statement otion
 299          */
 300         private function setDB2Option( $name, $const, $type ) {
 301                 if ( defined( $const )) {
 302                         if ( $type & self::CONN_OPTION ) {
 303                                 $this->mConnOptions[$name] = constant( $const );
 304                         }
 305                         if ( $type & self::STMT_OPTION ) {
 306                                 $this->mStmtOptions[$name] = constant( $const );
 307                         }
 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          * @return a fresh connection
 331          * @param $server String: hostname
 332          * @param $user String
 333          * @param $password String
 334          * @param $dbName String: database name
 335          */
 336         public function open( $server, $user, $password, $dbName )
 337         {
 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, $password )
 397         {
 398                 @$this->mConn = db2_pconnect( $dbName, $user, $password );
 399         }
 400
 401         /**
 402          * Opens an uncataloged database connection, sets mConn
 403          */
 404         protected function openUncataloged( $dbName, $user, $password, $server, $port )
 405         {
 406                 $str = "DRIVER={IBM DB2 ODBC DRIVER};";
 407                 $str .= "DATABASE=$dbName;";
 408                 $str .= "HOSTNAME=$server;";
 409                 // port was formerly validated to not be 0
 410                 $str .= "PORT=$port;";
 411                 $str .= "PROTOCOL=TCPIP;";
 412                 $str .= "UID=$user;";
 413                 $str .= "PWD=$password;";
 414
 415                 @$this->mConn = db2_pconnect( $str, $user, $password );
 416         }
 417
 418         /**
 419          * Closes a database connection, if it is open
 420          * Returns success, true if already closed
 421          */
 422         public function close() {
 423                 $this->mOpened = false;
 424                 if ( $this->mConn ) {
 425                         if ($this->trxLevel() > 0) {
 426                                 $this->commit();
 427                         }
 428                         return db2_close( $this->mConn );
 429                 }
 430                 else {
 431                         return true;
 432                 }
 433         }
 434
 435         /**
 436          * Returns a fresh instance of this class
 437          *
 438          * @param $server String: hostname of database server
 439          * @param $user String: username
 440          * @param $password String
 441          * @param $dbName String: database name on the server
 442          * @param $failFunction Callback (optional)
 443          * @param $flags Integer: database behaviour flags (optional, unused)
 444          * @return DatabaseIbm_db2 object
 445          */
 446         static function newFromParams( $server, $user, $password, $dbName,
 447                 $failFunction = false, $flags = 0 )
 448         {
 449                 return new DatabaseIbm_db2( $server, $user, $password, $dbName,
 450                         $failFunction, $flags );
 451         }
 452
 453         /**
 454          * Retrieves the most current database error
 455          * Forces a database rollback
 456          */
 457         public function lastError() {
 458                 $connerr = db2_conn_errormsg();
 459                 if ( $connerr ) {
 460                         //$this->rollback();
 461                         return $connerr;
 462                 }
 463                 $stmterr = db2_stmt_errormsg();
 464                 if ( $stmterr ) {
 465                         //$this->rollback();
 466                         return $stmterr;
 467                 }
 468
 469                 return false;
 470         }
 471
 472         /**
 473          * Get the last error number
 474          * Return 0 if no error
 475          * @return integer
 476          */
 477         public function lastErrno() {
 478                 $connerr = db2_conn_error();
 479                 if ( $connerr ) {
 480                         return $connerr;
 481                 }
 482                 $stmterr = db2_stmt_error();
 483                 if ( $stmterr ) {
 484                         return $stmterr;
 485                 }
 486                 return 0;
 487         }
 488
 489         /**
 490          * Is a database connection open?
 491          * @return
 492          */
 493         public function isOpen() { return $this->mOpened; }
 494
 495         /**
 496          * The DBMS-dependent part of query()
 497          * @param  $sql String: SQL query.
 498          * @return object Result object for fetch functions or false on failure
 499          * @access private
 500          */
 501         /*private*/
 502         public function doQuery( $sql ) {
 503                 $this->applySchema();
 504
 505                 $ret = db2_exec( $this->mConn, $sql, $this->mStmtOptions );
 506                 if( $ret == FALSE ) {
 507                         $error = db2_stmt_errormsg();
 508                         $this->installPrint( "<pre>$sql</pre>" );
 509                         $this->installPrint( $error );
 510                         throw new DBUnexpectedError( $this,  'SQL error: '
 511                                 . htmlspecialchars( $error ) );
 512                 }
 513                 $this->mLastResult = $ret;
 514                 $this->mAffectedRows = null;    // Not calculated until asked for
 515                 return $ret;
 516         }
 517
 518         /**
 519          * @return string Version information from the database
 520          */
 521         public function getServerVersion() {
 522                 $info = db2_server_info( $this->mConn );
 523                 return $info->DBMS_VER;
 524         }
 525
 526         /**
 527          * Queries whether a given table exists
 528          * @return boolean
 529          */
 530         public function tableExists( $table ) {
 531                 $schema = $this->mSchema;
 532                 $sql = <<< EOF
 533 SELECT COUNT( * ) FROM SYSIBM.SYSTABLES ST
 534 WHERE ST.NAME = '$table' AND ST.CREATOR = '$schema'
 535 EOF;
 536                 $res = $this->query( $sql );
 537                 if ( !$res ) return false;
 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' or $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          * Override if introduced to base Database class
 592          */
 593         public function initial_setup() {
 594                 // do nothing
 595         }
 596
 597         /**
 598          * Create tables, stored procedures, and so on
 599          */
 600         public function setup_database() {
 601                 try {
 602                         // TODO: switch to root login if available
 603
 604                         // Switch into the correct namespace
 605                         $this->applySchema();
 606                         $this->begin();
 607
 608                         $res = $this->sourceFile( "../maintenance/ibm_db2/tables.sql" );
 609                         if ( $res !== true ) {
 610                                 print " <b>FAILED</b>: " . htmlspecialchars( $res ) . "</li>";
 611                         } else {
 612                                 print " done</li>";
 613                         }
 614                         $res = $this->sourceFile( "../maintenance/ibm_db2/foreignkeys.sql" );
 615                         if ( $res !== true ) {
 616                                 print " <b>FAILED</b>: " . htmlspecialchars( $res ) . "</li>";
 617                         } else {
 618                                 print "<li>Foreign keys done</li>";
 619                         }
 620                         $res = null;
 621
 622                         // TODO: populate interwiki links
 623
 624                         if ( $this->lastError() ) {
 625                                 $this->installPrint(
 626                                         "Errors encountered during table creation -- rolled back" );
 627                                 $this->installPrint( "Please install again" );
 628                                 $this->rollback();
 629                         }
 630                         else {
 631                                 $this->commit();
 632                         }
 633                 }
 634                 catch ( MWException $mwe )
 635                 {
 636                         print "<br><pre>$mwe</pre><br>";
 637                 }
 638         }
 639
 640         /**
 641          * Escapes strings
 642          * Doesn't escape numbers
 643          * @param $s String: string to escape
 644          * @return escaped string
 645          */
 646         public function addQuotes( $s ) {
 647                 //$this->installPrint( "DB2::addQuotes( $s )\n" );
 648                 if ( is_null( $s ) ) {
 649                         return "NULL";
 650                 } else if ( $s instanceof Blob ) {
 651                         return "'" . $s->fetch( $s ) . "'";
 652                 } else if ( $s instanceof IBM_DB2Blob ) {
 653                         return "'" . $this->decodeBlob( $s ) . "'";
 654                 }
 655                 $s = $this->strencode( $s );
 656                 if ( is_numeric( $s ) ) {
 657                         return $s;
 658                 }
 659                 else {
 660                         return "'$s'";
 661                 }
 662         }
 663
 664         /**
 665          * Verifies that a DB2 column/field type is numeric
 666          * @return bool true if numeric
 667          * @param $type String: DB2 column type
 668          */
 669         public function is_numeric_type( $type ) {
 670                 switch ( strtoupper( $type )) {
 671                 case 'SMALLINT':
 672                 case 'INTEGER':
 673                 case 'INT':
 674                 case 'BIGINT':
 675                 case 'DECIMAL':
 676                 case 'REAL':
 677                 case 'DOUBLE':
 678                 case 'DECFLOAT':
 679                         return true;
 680                 }
 681                 return false;
 682         }
 683
 684         /**
 685          * Alias for addQuotes()
 686          * @param $s String: string to escape
 687          * @return escaped string
 688          */
 689         public function strencode( $s ) {
 690                 // Bloody useless function
 691                 //  Prepends backslashes to \x00, \n, \r, \, ', " and \x1a.
 692                 //  But also necessary
 693                 $s = db2_escape_string( $s );
 694                 // Wide characters are evil -- some of them look like '
 695                 $s = utf8_encode( $s );
 696                 // Fix its stupidity
 697                 $from = array(  "\\\\", "\\'",  '\\n',  '\\t',  '\\"',  '\\r' );
 698                 $to =   array(          "\\",           "''",           "\n",           "\t",           '"',            "\r" );
 699                 $s = str_replace( $from, $to, $s ); // DB2 expects '', not \' escaping
 700                 return $s;
 701         }
 702
 703         /**
 704          * Switch into the database schema
 705          */
 706         protected function applySchema() {
 707                 if ( !( $this->mSchemaSet ) ) {
 708                         $this->mSchemaSet = true;
 709                         $this->begin();
 710                         $this->doQuery( "SET SCHEMA = $this->mSchema" );
 711                         $this->commit();
 712                 }
 713         }
 714
 715         /**
 716          * Start a transaction (mandatory)
 717          */
 718         public function begin( $fname = 'DatabaseIbm_db2::begin' ) {
 719                 // BEGIN is implicit for DB2
 720                 // However, it requires that AutoCommit be off.
 721
 722                 // Some MediaWiki code is still transaction-less (?).
 723                 // The strategy is to keep AutoCommit on for that code
 724                 //  but switch it off whenever a transaction is begun.
 725                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_OFF );
 726
 727                 $this->mTrxLevel = 1;
 728         }
 729
 730         /**
 731          * End a transaction
 732          * Must have a preceding begin()
 733          */
 734         public function commit( $fname = 'DatabaseIbm_db2::commit' ) {
 735                 db2_commit( $this->mConn );
 736
 737                 // Some MediaWiki code is still transaction-less (?).
 738                 // The strategy is to keep AutoCommit on for that code
 739                 //  but switch it off whenever a transaction is begun.
 740                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 741
 742                 $this->mTrxLevel = 0;
 743         }
 744
 745         /**
 746          * Cancel a transaction
 747          */
 748         public function rollback( $fname = 'DatabaseIbm_db2::rollback' ) {
 749                 db2_rollback( $this->mConn );
 750                 // turn auto-commit back on
 751                 // not sure if this is appropriate
 752                 db2_autocommit( $this->mConn, DB2_AUTOCOMMIT_ON );
 753                 $this->mTrxLevel = 0;
 754         }
 755
 756         /**
 757          * Makes an encoded list of strings from an array
 758          * $mode:
 759          *   LIST_COMMA         - comma separated, no field names
 760          *   LIST_AND           - ANDed WHERE clause (without the WHERE)
 761          *   LIST_OR            - ORed WHERE clause (without the WHERE)
 762          *   LIST_SET           - comma separated with field names, like a SET clause
 763          *   LIST_NAMES         - comma separated field names
 764          *   LIST_SET_PREPARED  - like LIST_SET, except with ? tokens as values
 765          */
 766         function makeList( $a, $mode = LIST_COMMA ) {
 767                 if ( !is_array( $a ) ) {
 768                         throw new DBUnexpectedError( $this,
 769                                 'DatabaseBase::makeList called with incorrect parameters' );
 770                 }
 771
 772                 // if this is for a prepared UPDATE statement
 773                 // (this should be promoted to the parent class
 774                 //  once other databases use prepared statements)
 775                 if ( $mode == LIST_SET_PREPARED ) {
 776                         $first = true;
 777                         $list = '';
 778                         foreach ( $a as $field => $value ) {
 779                                 if ( !$first ) {
 780                                         $list .= ", $field = ?";
 781                                 }
 782                                 else {
 783                                         $list .= "$field = ?";
 784                                         $first = false;
 785                                 }
 786                         }
 787                         $list .= '';
 788
 789                         return $list;
 790                 }
 791
 792                 // otherwise, call the usual function
 793                 return parent::makeList( $a, $mode );
 794         }
 795
 796         /**
 797          * Construct a LIMIT query with optional offset
 798          * This is used for query pages
 799          * @param $sql string SQL query we will append the limit too
 800          * @param $limit integer the SQL limit
 801          * @param $offset integer the SQL offset (default false)
 802          */
 803         public function limitResult( $sql, $limit, $offset=false ) {
 804                 if( !is_numeric( $limit ) ) {
 805                         throw new DBUnexpectedError( $this,
 806                                 "Invalid non-numeric limit passed to limitResult()\n" );
 807                 }
 808                 if( $offset ) {
 809                         if ( stripos( $sql, 'where' ) === false ) {
 810                                 return "$sql AND ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 811                         }
 812                         else {
 813                                 return "$sql WHERE ( ROWNUM BETWEEN $offset AND $offset+$limit )";
 814                         }
 815                 }
 816                 return "$sql FETCH FIRST $limit ROWS ONLY ";
 817         }
 818
 819         /**
 820          * Handle reserved keyword replacement in table names
 821          * @return
 822          * @param $name Object
 823          */
 824         public function tableName( $name ) {
 825                 // we want maximum compatibility with MySQL schema
 826                 return $name;
 827         }
 828
 829         /**
 830          * Generates a timestamp in an insertable format
 831          * @return string timestamp value
 832          * @param $ts timestamp
 833          */
 834         public function timestamp( $ts=0 ) {
 835                 // TS_MW cannot be easily distinguished from an integer
 836                 return wfTimestamp( TS_DB2, $ts );
 837         }
 838
 839         /**
 840          * Return the next in a sequence, save the value for retrieval via insertId()
 841          * @param $seqName String: name of a defined sequence in the database
 842          * @return next value in that sequence
 843          */
 844         public function nextSequenceValue( $seqName ) {
 845                 // Not using sequences in the primary schema to allow for easier migration
 846                 //  from MySQL
 847                 // Emulating MySQL behaviour of using NULL to signal that sequences
 848                 // aren't used
 849                 /*
 850                 $safeseq = preg_replace( "/'/", "''", $seqName );
 851                 $res = $this->query( "VALUES NEXTVAL FOR $safeseq" );
 852                 $row = $this->fetchRow( $res );
 853                 $this->mInsertId = $row[0];
 854                 return $this->mInsertId;
 855                 */
 856                 return null;
 857         }
 858
 859         /**
 860          * This must be called after nextSequenceVal
 861          * @return Last sequence value used as a primary key
 862          */
 863         public function insertId() {
 864                 return $this->mInsertId;
 865         }
 866
 867         /**
 868          * Updates the mInsertId property with the value of the last insert
 869          *  into a generated column
 870          * @param $table      String: sanitized table name
 871          * @param $primaryKey Mixed: string name of the primary key
 872          * @param $stmt       Resource: prepared statement resource
 873          *  of the SELECT primary_key FROM FINAL TABLE ( INSERT ... ) form
 874          */
 875         private function calcInsertId( $table, $primaryKey, $stmt ) {
 876                 if ( $primaryKey ) {
 877                         $this->mInsertId = db2_last_insert_id( $this->mConn );
 878                 }
 879         }
 880
 881         /**
 882          * INSERT wrapper, inserts an array into a table
 883          *
 884          * $args may be a single associative array, or an array of arrays
 885          *  with numeric keys, for multi-row insert
 886          *
 887          * @param $table   String: Name of the table to insert to.
 888          * @param $args    Array: Items to insert into the table.
 889          * @param $fname   String: Name of the function, for profiling
 890          * @param $options String or Array. Valid options: IGNORE
 891          *
 892          * @return bool Success of insert operation. IGNORE always returns true.
 893          */
 894         public function insert( $table, $args, $fname = 'DatabaseIbm_db2::insert',
 895                 $options = array() )
 896         {
 897                 if ( !count( $args ) ) {
 898                         return true;
 899                 }
 900                 // get database-specific table name (not used)
 901                 $table = $this->tableName( $table );
 902                 // format options as an array
 903                 $options = IBM_DB2Helper::makeArray( $options );
 904                 // format args as an array of arrays
 905                 if ( !( isset( $args[0] ) && is_array( $args[0] ) ) ) {
 906                         $args = array( $args );
 907                 }
 908
 909                 // prevent insertion of NULL into primary key columns
 910                 list( $args, $primaryKeys ) = $this->removeNullPrimaryKeys( $table, $args );
 911                 // if there's only one primary key
 912                 // we'll be able to read its value after insertion
 913                 $primaryKey = false;
 914                 if ( count( $primaryKeys ) == 1 ) {
 915                         $primaryKey = $primaryKeys[0];
 916                 }
 917
 918                 // get column names
 919                 $keys = array_keys( $args[0] );
 920                 $key_count = count( $keys );
 921
 922                 // If IGNORE is set, we use savepoints to emulate mysql's behavior
 923                 $ignore = in_array( 'IGNORE', $options ) ? 'mw' : '';
 924
 925                 // assume success
 926                 $res = true;
 927                 // If we are not in a transaction, we need to be for savepoint trickery
 928                 if ( ! $this->mTrxLevel ) {
 929                         $this->begin();
 930                 }
 931
 932                 $sql = "INSERT INTO $table ( " . implode( ',', $keys ) . ' ) VALUES ';
 933                 if ( $key_count == 1 ) {
 934                         $sql .= '( ? )';
 935                 } else {
 936                         $sql .= '( ?' . str_repeat( ',?', $key_count-1 ) . ' )';
 937                 }
 938                 //$this->installPrint( "Preparing the following SQL:" );
 939                 //$this->installPrint( "$sql" );
 940                 //$this->installPrint( print_r( $args, true ));
 941                 $stmt = $this->prepare( $sql );
 942
 943                 // start a transaction/enter transaction mode
 944                 $this->begin();
 945
 946                 if ( !$ignore ) {
 947                         //$first = true;
 948                         foreach ( $args as $row ) {
 949                                 //$this->installPrint( "Inserting " . print_r( $row, true ));
 950                                 // insert each row into the database
 951                                 $res = $res & $this->execute( $stmt, $row );
 952                                 if ( !$res ) {
 953                                         $this->installPrint( "Last error:" );
 954                                         $this->installPrint( $this->lastError() );
 955                                 }
 956                                 // get the last inserted value into a generated column
 957                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 958                         }
 959                 }
 960                 else {
 961                         $olde = error_reporting( 0 );
 962                         // For future use, we may want to track the number of actual inserts
 963                         // Right now, insert (all writes) simply return true/false
 964                         $numrowsinserted = 0;
 965
 966                         // always return true
 967                         $res = true;
 968
 969                         foreach ( $args as $row ) {
 970                                 $overhead = "SAVEPOINT $ignore ON ROLLBACK RETAIN CURSORS";
 971                                 db2_exec( $this->mConn, $overhead, $this->mStmtOptions );
 972
 973
 974                                 $this->execute( $stmt, $row );
 975
 976                                 if ( !$res2 ) {
 977                                         $this->installPrint( "Last error:" );
 978                                         $this->installPrint( $this->lastError() );
 979                                 }
 980                                 // get the last inserted value into a generated column
 981                                 $this->calcInsertId( $table, $primaryKey, $stmt );
 982
 983                                 $errNum = $this->lastErrno();
 984                                 if ( $errNum ) {
 985                                         db2_exec( $this->mConn, "ROLLBACK TO SAVEPOINT $ignore",
 986                                                 $this->mStmtOptions );
 987                                 }
 988                                 else {
 989                                         db2_exec( $this->mConn, "RELEASE SAVEPOINT $ignore",
 990                                                 $this->mStmtOptions );
 991                                         $numrowsinserted++;
 992                                 }
 993                         }
 994
 995                         $olde = error_reporting( $olde );
 996                         // Set the affected row count for the whole operation
 997                         $this->mAffectedRows = $numrowsinserted;
 998                 }
 999                 // commit either way
1000                 $this->commit();
1001                 $this->freePrepared( $stmt );
1002
1003                 return $res;
1004         }
1005
1006         /**
1007          * Given a table name and a hash of columns with values
1008          * Removes primary key columns from the hash where the value is NULL
1009          *
1010          * @param $table String: name of the table
1011          * @param $args Array of hashes of column names with values
1012          * @return Array: tuple( filtered array of columns, array of primary keys )
1013          */
1014         private function removeNullPrimaryKeys( $table, $args ) {
1015                 $schema = $this->mSchema;
1016                 // find out the primary keys
1017                 $keyres = db2_primary_keys( $this->mConn, null, strtoupper( $schema ),
1018                         strtoupper( $table ));
1019                 $keys = array();
1020                 for (
1021                         $row = $this->fetchObject( $keyres );
1022                         $row != null;
1023                         $row = $this->fetchObject( $keyres ))
1024                 {
1025                         $keys[] = strtolower( $row->column_name );
1026                 }
1027                 // remove primary keys
1028                 foreach ( $args as $ai => $row ) {
1029                         foreach ( $keys as $ki => $key ) {
1030                                 if ( $row[$key] == null ) {
1031                                         unset( $row[$key] );
1032                                 }
1033                         }
1034                         $args[$ai] = $row;
1035                 }
1036                 // return modified hash
1037                 return array( $args, $keys );
1038         }
1039
1040         /**
1041          * UPDATE wrapper, takes a condition array and a SET array
1042          *
1043          * @param $table  String: The table to UPDATE
1044          * @param $values An array of values to SET
1045          * @param $conds  An array of conditions ( WHERE ). Use '*' to update all rows.
1046          * @param $fname  String: The Class::Function calling this function
1047          *                ( for the log )
1048          * @param $options An array of UPDATE options, can be one or
1049          *                 more of IGNORE, LOW_PRIORITY
1050          * @return Boolean
1051          */
1052         public function update( $table, $values, $conds, $fname = 'Database::update',
1053                 $options = array() )
1054         {
1055                 $table = $this->tableName( $table );
1056                 $opts = $this->makeUpdateOptions( $options );
1057                 $sql = "UPDATE $opts $table SET "
1058                         . $this->makeList( $values, LIST_SET_PREPARED );
1059                 if ( $conds != '*' ) {
1060                         $sql .= " WHERE " . $this->makeList( $conds, LIST_AND );
1061                 }
1062                 $stmt = $this->prepare( $sql );
1063                 $this->installPrint( "UPDATE: " . print_r( $values, TRUE ));
1064                 // assuming for now that an array with string keys will work
1065                 // if not, convert to simple array first
1066                 $result = $this->execute( $stmt, $values );
1067                 $this->freePrepared( $stmt );
1068
1069                 return $result;
1070         }
1071
1072         /**
1073          * DELETE query wrapper
1074          *
1075          * Use $conds == "*" to delete all rows
1076          */
1077         public function delete( $table, $conds, $fname = 'Database::delete' ) {
1078                 if ( !$conds ) {
1079                         throw new DBUnexpectedError( $this,
1080                         'Database::delete() called with no conditions' );
1081                 }
1082                 $table = $this->tableName( $table );
1083                 $sql = "DELETE FROM $table";
1084                 if ( $conds != '*' ) {
1085                         $sql .= ' WHERE ' . $this->makeList( $conds, LIST_AND );
1086                 }
1087                 $result = $this->query( $sql, $fname );
1088
1089                 return $result;
1090         }
1091
1092         /**
1093          * Returns the number of rows affected by the last query or 0
1094          * @return Integer: the number of rows affected by the last query
1095          */
1096         public function affectedRows() {
1097                 if ( !is_null( $this->mAffectedRows ) ) {
1098                         // Forced result for simulated queries
1099                         return $this->mAffectedRows;
1100                 }
1101                 if( empty( $this->mLastResult ) )
1102                         return 0;
1103                 return db2_num_rows( $this->mLastResult );
1104         }
1105
1106         /**
1107          * Simulates REPLACE with a DELETE followed by INSERT
1108          * @param $table Object
1109          * @param $uniqueIndexes Array consisting of indexes and arrays of indexes
1110          * @param $rows Array: rows to insert
1111          * @param $fname String: name of the function for profiling
1112          * @return nothing
1113          */
1114         function replace( $table, $uniqueIndexes, $rows,
1115                 $fname = 'DatabaseIbm_db2::replace' )
1116         {
1117                 $table = $this->tableName( $table );
1118
1119                 if ( count( $rows )==0 ) {
1120                         return;
1121                 }
1122
1123                 # Single row case
1124                 if ( !is_array( reset( $rows ) ) ) {
1125                         $rows = array( $rows );
1126                 }
1127
1128                 foreach( $rows as $row ) {
1129                         # Delete rows which collide
1130                         if ( $uniqueIndexes ) {
1131                                 $sql = "DELETE FROM $table WHERE ";
1132                                 $first = true;
1133                                 foreach ( $uniqueIndexes as $index ) {
1134                                         if ( $first ) {
1135                                                 $first = false;
1136                                                 $sql .= "( ";
1137                                         } else {
1138                                                 $sql .= ' ) OR ( ';
1139                                         }
1140                                         if ( is_array( $index ) ) {
1141                                                 $first2 = true;
1142                                                 foreach ( $index as $col ) {
1143                                                         if ( $first2 ) {
1144                                                                 $first2 = false;
1145                                                         } else {
1146                                                                 $sql .= ' AND ';
1147                                                         }
1148                                                         $sql .= $col . '=' . $this->addQuotes( $row[$col] );
1149                                                 }
1150                                         } else {
1151                                                 $sql .= $index . '=' . $this->addQuotes( $row[$index] );
1152                                         }
1153                                 }
1154                                 $sql .= ' )';
1155                                 $this->query( $sql, $fname );
1156                         }
1157
1158                         # Now insert the row
1159                         $sql = "INSERT INTO $table ( "
1160                                 . $this->makeList( array_keys( $row ), LIST_NAMES )
1161                                 .' ) VALUES ( ' . $this->makeList( $row, LIST_COMMA ) . ' )';
1162                         $this->query( $sql, $fname );
1163                 }
1164         }
1165
1166         /**
1167          * Returns the number of rows in the result set
1168          * Has to be called right after the corresponding select query
1169          * @param $res Object result set
1170          * @return Integer: number of rows
1171          */
1172         public function numRows( $res ) {
1173                 if ( $res instanceof ResultWrapper ) {
1174                         $res = $res->result;
1175                 }
1176                 if ( $this->mNumRows ) {
1177                         return $this->mNumRows;
1178                 }
1179                 else {
1180                         return 0;
1181                 }
1182         }
1183
1184         /**
1185          * Moves the row pointer of the result set
1186          * @param $res Object: result set
1187          * @param $row Integer: row number
1188          * @return success or failure
1189          */
1190         public function dataSeek( $res, $row ) {
1191                 if ( $res instanceof ResultWrapper ) {
1192                         $res = $res->result;
1193                 }
1194                 return db2_fetch_row( $res, $row );
1195         }
1196
1197         ###
1198         # Fix notices in Block.php
1199         ###
1200
1201         /**
1202          * Frees memory associated with a statement resource
1203          * @param $res Object: statement resource to free
1204          * @return Boolean success or failure
1205          */
1206         public function freeResult( $res ) {
1207                 if ( $res instanceof ResultWrapper ) {
1208                         $res = $res->result;
1209                 }
1210                 if ( !@db2_free_result( $res ) ) {
1211                         throw new DBUnexpectedError( $this,  "Unable to free DB2 result\n" );
1212                 }
1213         }
1214
1215         /**
1216          * Returns the number of columns in a resource
1217          * @param $res Object: statement resource
1218          * @return Number of fields/columns in resource
1219          */
1220         public function numFields( $res ) {
1221                 if ( $res instanceof ResultWrapper ) {
1222                         $res = $res->result;
1223                 }
1224                 return db2_num_fields( $res );
1225         }
1226
1227         /**
1228          * Returns the nth column name
1229          * @param $res Object: statement resource
1230          * @param $n Integer: Index of field or column
1231          * @return String name of nth column
1232          */
1233         public function fieldName( $res, $n ) {
1234                 if ( $res instanceof ResultWrapper ) {
1235                         $res = $res->result;
1236                 }
1237                 return db2_field_name( $res, $n );
1238         }
1239
1240         /**
1241          * SELECT wrapper
1242          *
1243          * @param $table   Array or string, table name(s) (prefix auto-added)
1244          * @param $vars    Array or string, field name(s) to be retrieved
1245          * @param $conds   Array or string, condition(s) for WHERE
1246          * @param $fname   String: calling function name (use __METHOD__)
1247          *                 for logs/profiling
1248          * @param $options Associative array of options
1249          *                 (e.g. array('GROUP BY' => 'page_title')),
1250          *                 see Database::makeSelectOptions code for list of
1251          *                 supported stuff
1252          * @param $join_conds Associative array of table join conditions (optional)
1253          *                    (e.g. array( 'page' => array('LEFT JOIN',
1254          *                    'page_latest=rev_id') )
1255          * @return Mixed: database result resource for fetch functions or false
1256          *                 on failure
1257          */
1258         public function select( $table, $vars, $conds='', $fname = 'DatabaseIbm_db2::select', $options = array(), $join_conds = array() )
1259         {
1260                 $res = parent::select( $table, $vars, $conds, $fname, $options,
1261                         $join_conds );
1262
1263                 // We must adjust for offset
1264                 if ( isset( $options['LIMIT'] ) ) {
1265                         if ( isset ( $options['OFFSET'] ) ) {
1266                                 $limit = $options['LIMIT'];
1267                                 $offset = $options['OFFSET'];
1268                         }
1269                 }
1270
1271
1272                 // DB2 does not have a proper num_rows() function yet, so we must emulate
1273                 // DB2 9.5.4 and the corresponding ibm_db2 driver will introduce
1274                 //  a working one
1275                 // TODO: Yay!
1276
1277                 // we want the count
1278                 $vars2 = array( 'count( * ) as num_rows' );
1279                 // respecting just the limit option
1280                 $options2 = array();
1281                 if ( isset( $options['LIMIT'] ) ) {
1282                         $options2['LIMIT'] = $options['LIMIT'];
1283                 }
1284                 // but don't try to emulate for GROUP BY
1285                 if ( isset( $options['GROUP BY'] ) ) {
1286                         return $res;
1287                 }
1288
1289                 $res2 = parent::select( $table, $vars2, $conds, $fname, $options2,
1290                         $join_conds );
1291                 $obj = $this->fetchObject( $res2 );
1292                 $this->mNumRows = $obj->num_rows;
1293
1294
1295                 return $res;
1296         }
1297
1298         /**
1299          * Handles ordering, grouping, and having options ('GROUP BY' => colname)
1300          * Has limited support for per-column options (colnum => 'DISTINCT')
1301          *
1302          * @private
1303          *
1304          * @param $options Associative array of options to be turned into
1305          *              an SQL query, valid keys are listed in the function.
1306          * @return Array
1307          */
1308         function makeSelectOptions( $options ) {
1309                 $preLimitTail = $postLimitTail = '';
1310                 $startOpts = '';
1311
1312                 $noKeyOptions = array();
1313                 foreach ( $options as $key => $option ) {
1314                         if ( is_numeric( $key ) ) {
1315                                 $noKeyOptions[$option] = true;
1316                         }
1317                 }
1318
1319                 if ( isset( $options['GROUP BY'] ) ) {
1320                         $preLimitTail .= " GROUP BY {$options['GROUP BY']}";
1321                 }
1322                 if ( isset( $options['HAVING'] ) ) {
1323                         $preLimitTail .= " HAVING {$options['HAVING']}";
1324                 }
1325                 if ( isset( $options['ORDER BY'] ) ) {
1326                         $preLimitTail .= " ORDER BY {$options['ORDER BY']}";
1327                 }
1328
1329                 if ( isset( $noKeyOptions['DISTINCT'] )
1330                         || isset( $noKeyOptions['DISTINCTROW'] ) )
1331                 {
1332                         $startOpts .= 'DISTINCT';
1333                 }
1334
1335                 return array( $startOpts, '', $preLimitTail, $postLimitTail );
1336         }
1337
1338         /**
1339          * Returns link to IBM DB2 free download
1340          * @return string wikitext of a link to the server software's web site
1341          */
1342         public static function getSoftwareLink() {
1343                 return "[http://www.ibm.com/db2/express/ IBM DB2]";
1344         }
1345
1346         /**
1347          * Get search engine class. All subclasses of this
1348          * need to implement this if they wish to use searching.
1349          *
1350          * @return String
1351          */
1352         public function getSearchEngine() {
1353                 return "SearchIBM_DB2";
1354         }
1355
1356         /**
1357          * Did the last database access fail because of deadlock?
1358          * @return Boolean
1359          */
1360         public function wasDeadlock() {
1361                 // get SQLSTATE
1362                 $err = $this->lastErrno();
1363                 switch( $err ) {
1364                         // This is literal port of the MySQL logic and may be wrong for DB2
1365                         case '40001':   // sql0911n, Deadlock or timeout, rollback
1366                         case '57011':   // sql0904n, Resource unavailable, no rollback
1367                         case '57033':   // sql0913n, Deadlock or timeout, no rollback
1368                         $this->installPrint( "In a deadlock because of SQLSTATE $err" );
1369                         return true;
1370                 }
1371                 return false;
1372         }
1373
1374         /**
1375          * Ping the server and try to reconnect if it there is no connection
1376          * The connection may be closed and reopened while this happens
1377          * @return Boolean: whether the connection exists
1378          */
1379         public function ping() {
1380                 // db2_ping() doesn't exist
1381                 // Emulate
1382                 $this->close();
1383                 $this->mConn = $this->openUncataloged( $this->mDBName, $this->mUser,
1384                         $this->mPassword, $this->mServer, $this->mPort );
1385
1386                 return false;
1387         }
1388         ######################################
1389         # Unimplemented and not applicable
1390         ######################################
1391         /**
1392          * Not implemented
1393          * @return string ''
1394          */
1395         public function getStatus( $which="%" ) {
1396                         $this->installPrint( 'Not implemented for DB2: getStatus()' );
1397                         return '';
1398         }
1399         /**
1400          * Not implemented
1401          * @return string $sql
1402          */
1403         public function limitResultForUpdate( $sql, $num ) {
1404                 $this->installPrint( 'Not implemented for DB2: limitResultForUpdate()' );
1405                 return $sql;
1406         }
1407
1408         /**
1409          * Only useful with fake prepare like in base Database class
1410          * @return      string
1411          */
1412         public function fillPreparedArg( $matches ) {
1413                 $this->installPrint( 'Not useful for DB2: fillPreparedArg()' );
1414                 return '';
1415         }
1416
1417         ######################################
1418         # Reflection
1419         ######################################
1420
1421         /**
1422          * Returns information about an index
1423          * If errors are explicitly ignored, returns NULL on failure
1424          * @param $table String: table name
1425          * @param $index String: index name
1426          * @param $fname String: function name for logging and profiling
1427          * @return Object query row in object form
1428          */
1429         public function indexInfo( $table, $index,
1430                 $fname = 'DatabaseIbm_db2::indexExists' )
1431         {
1432                 $table = $this->tableName( $table );
1433                 $sql = <<<SQL
1434 SELECT name as indexname
1435 FROM sysibm.sysindexes si
1436 WHERE si.name='$index' AND si.tbname='$table'
1437 AND sc.tbcreator='$this->mSchema'
1438 SQL;
1439                 $res = $this->query( $sql, $fname );
1440                 if ( !$res ) {
1441                         return null;
1442                 }
1443                 $row = $this->fetchObject( $res );
1444                 if ( $row != null ) {
1445                         return $row;
1446                 }
1447                 else return false;
1448         }
1449
1450         /**
1451          * Returns an information object on a table column
1452          * @param $table String: table name
1453          * @param $field String: column name
1454          * @return IBM_DB2Field
1455          */
1456         public function fieldInfo( $table, $field ) {
1457                 return IBM_DB2Field::fromText( $this, $table, $field );
1458         }
1459
1460         /**
1461          * db2_field_type() wrapper
1462          * @param $res Object: result of executed statement
1463          * @param $index Mixed: number or name of the column
1464          * @return String column type
1465          */
1466         public function fieldType( $res, $index ) {
1467                 if ( $res instanceof ResultWrapper ) {
1468                         $res = $res->result;
1469                 }
1470                 return db2_field_type( $res, $index );
1471         }
1472
1473         /**
1474          * Verifies that an index was created as unique
1475          * @param $table String: table name
1476          * @param $index String: index name
1477          * @param $fname function name for profiling
1478          * @return Bool
1479          */
1480         public function indexUnique ( $table, $index,
1481                 $fname = 'Database::indexUnique' )
1482         {
1483                 $table = $this->tableName( $table );
1484                 $sql = <<<SQL
1485 SELECT si.name as indexname
1486 FROM sysibm.sysindexes si
1487 WHERE si.name='$index' AND si.tbname='$table'
1488 AND sc.tbcreator='$this->mSchema'
1489 AND si.uniquerule IN ( 'U', 'P' )
1490 SQL;
1491                 $res = $this->query( $sql, $fname );
1492                 if ( !$res ) {
1493                         return null;
1494                 }
1495                 if ( $this->fetchObject( $res ) ) {
1496                         return true;
1497                 }
1498                 return false;
1499
1500         }
1501
1502         /**
1503          * Returns the size of a text field, or -1 for "unlimited"
1504          * @param $table String: table name
1505          * @param $field String: column name
1506          * @return Integer: length or -1 for unlimited
1507          */
1508         public function textFieldSize( $table, $field ) {
1509                 $table = $this->tableName( $table );
1510                 $sql = <<<SQL
1511 SELECT length as size
1512 FROM sysibm.syscolumns sc
1513 WHERE sc.name='$field' AND sc.tbname='$table'
1514 AND sc.tbcreator='$this->mSchema'
1515 SQL;
1516                 $res = $this->query( $sql );
1517                 $row = $this->fetchObject( $res );
1518                 $size = $row->size;
1519                 return $size;
1520         }
1521
1522         /**
1523          * DELETE where the condition is a join
1524          * @param $delTable String: deleting from this table
1525          * @param $joinTable String: using data from this table
1526          * @param $delVar String: variable in deleteable table
1527          * @param $joinVar String: variable in data table
1528          * @param $conds Array: conditionals for join table
1529          * @param $fname String: function name for profiling
1530          */
1531         public function deleteJoin( $delTable, $joinTable, $delVar, $joinVar,
1532                 $conds, $fname = "DatabaseIbm_db2::deleteJoin" )
1533         {
1534                 if ( !$conds ) {
1535                         throw new DBUnexpectedError( $this,
1536                         'Database::deleteJoin() called with empty $conds' );
1537                 }
1538
1539                 $delTable = $this->tableName( $delTable );
1540                 $joinTable = $this->tableName( $joinTable );
1541                 $sql = <<<SQL
1542 DELETE FROM $delTable
1543 WHERE $delVar IN (
1544   SELECT $joinVar FROM $joinTable
1545
1546 SQL;
1547                 if ( $conds != '*' ) {
1548                         $sql .= 'WHERE ' . $this->makeList( $conds, LIST_AND );
1549                 }
1550                 $sql .= ' )';
1551
1552                 $this->query( $sql, $fname );
1553         }
1554
1555         /**
1556          * Description is left as an exercise for the reader
1557          * @param $b Mixed: data to be encoded
1558          * @return IBM_DB2Blob
1559          */
1560         public function encodeBlob( $b ) {
1561                 return new IBM_DB2Blob( $b );
1562         }
1563
1564         /**
1565          * Description is left as an exercise for the reader
1566          * @param $b IBM_DB2Blob: data to be decoded
1567          * @return mixed
1568          */
1569         public function decodeBlob( $b ) {
1570                 return "$b";
1571         }
1572
1573         /**
1574          * Convert into a list of string being concatenated
1575          * @param $stringList Array: strings that need to be joined together
1576          *                    by the SQL engine
1577          * @return String: joined by the concatenation operator
1578          */
1579         public function buildConcat( $stringList ) {
1580                 // || is equivalent to CONCAT
1581                 // Sample query: VALUES 'foo' CONCAT 'bar' CONCAT 'baz'
1582                 return implode( ' || ', $stringList );
1583         }
1584
1585         /**
1586          * Generates the SQL required to convert a DB2 timestamp into a Unix epoch
1587          * @param $column String: name of timestamp column
1588          * @return String: SQL code
1589          */
1590         public function extractUnixEpoch( $column ) {
1591                 // TODO
1592                 // see SpecialAncientpages
1593         }
1594
1595         ######################################
1596         # Prepared statements
1597         ######################################
1598
1599         /**
1600          * Intended to be compatible with the PEAR::DB wrapper functions.
1601          * http://pear.php.net/manual/en/package.database.db.intro-execute.php
1602          *
1603          * ? = scalar value, quoted as necessary
1604          * ! = raw SQL bit (a function for instance)
1605          * & = filename; reads the file and inserts as a blob
1606          *     (we don't use this though...)
1607          * @param $sql String: SQL statement with appropriate markers
1608          * @param $func String: Name of the function, for profiling
1609          * @return resource a prepared DB2 SQL statement
1610          */
1611         public function prepare( $sql, $func = 'DB2::prepare' ) {
1612                 $stmt = db2_prepare( $this->mConn, $sql, $this->mStmtOptions );
1613                 return $stmt;
1614         }
1615
1616         /**
1617          * Frees resources associated with a prepared statement
1618          * @return Boolean success or failure
1619          */
1620         public function freePrepared( $prepared ) {
1621                 return db2_free_stmt( $prepared );
1622         }
1623
1624         /**
1625          * Execute a prepared query with the various arguments
1626          * @param $prepared String: the prepared sql
1627          * @param $args Mixed: either an array here, or put scalars as varargs
1628          * @return Resource: results object
1629          */
1630         public function execute( $prepared, $args = null ) {
1631                 if( !is_array( $args ) ) {
1632                         # Pull the var args
1633                         $args = func_get_args();
1634                         array_shift( $args );
1635                 }
1636                 $res = db2_execute( $prepared, $args );
1637                 if ( !$res ) {
1638                         $this->installPrint( db2_stmt_errormsg() );
1639                 }
1640                 return $res;
1641         }
1642
1643         /**
1644          * Prepare & execute an SQL statement, quoting and inserting arguments
1645          * in the appropriate places.
1646          * @param $query String
1647          * @param $args ...
1648          */
1649         public function safeQuery( $query, $args = null ) {
1650                 // copied verbatim from Database.php
1651                 $prepared = $this->prepare( $query, 'DB2::safeQuery' );
1652                 if( !is_array( $args ) ) {
1653                         # Pull the var args
1654                         $args = func_get_args();
1655                         array_shift( $args );
1656                 }
1657                 $retval = $this->execute( $prepared, $args );
1658                 $this->freePrepared( $prepared );
1659                 return $retval;
1660         }
1661
1662         /**
1663          * For faking prepared SQL statements on DBs that don't support
1664          * it directly.
1665          * @param $preparedQuery String: a 'preparable' SQL statement
1666          * @param $args Array of arguments to fill it with
1667          * @return String: executable statement
1668          */
1669         public function fillPrepared( $preparedQuery, $args ) {
1670                 reset( $args );
1671                 $this->preparedArgs =& $args;
1672
1673                 foreach ( $args as $i => $arg ) {
1674                         db2_bind_param( $preparedQuery, $i+1, $args[$i] );
1675                 }
1676
1677                 return $preparedQuery;
1678         }
1679
1680         /**
1681          * Switches module between regular and install modes
1682          */
1683         public function setMode( $mode ) {
1684                 $old =  $this->mMode;
1685                 $this->mMode = $mode;
1686                 return $old;
1687         }
1688
1689         /**
1690          * Bitwise negation of a column or value in SQL
1691          * Same as (~field) in C
1692          * @param $field String
1693          * @return String
1694          */
1695         function bitNot( $field ) {
1696                 //expecting bit-fields smaller than 4bytes
1697                 return "BITNOT( $field )";
1698         }
1699
1700         /**
1701          * Bitwise AND of two columns or values in SQL
1702          * Same as (fieldLeft & fieldRight) in C
1703          * @param $fieldLeft String
1704          * @param $fieldRight String
1705          * @return String
1706          */
1707         function bitAnd( $fieldLeft, $fieldRight ) {
1708                 return "BITAND( $fieldLeft, $fieldRight )";
1709         }
1710
1711         /**
1712          * Bitwise OR of two columns or values in SQL
1713          * Same as (fieldLeft | fieldRight) in C
1714          * @param $fieldLeft String
1715          * @param $fieldRight String
1716          * @return String
1717          */
1718         function bitOr( $fieldLeft, $fieldRight ) {
1719                 return "BITOR( $fieldLeft, $fieldRight )";
1720         }
1721 }
1722
1723 class IBM_DB2Helper {
1724         public static function makeArray( $maybeArray ) {
1725                 if ( !is_array( $maybeArray ) ) {
1726                         return array( $maybeArray );
1727                 }
1728
1729                 return $maybeArray;
1730         }
1731 }