aboutsummaryrefslogtreecommitdiff
path: root/lib/phpFlickr/PEAR/DB/mysql.php
blob: 3ae0adf86cddbfe7612daec8ff4b279fbaaa2202 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
<?php

/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */

/**
 * The PEAR DB driver for PHP's mysql extension
 * for interacting with MySQL databases
 *
 * PHP versions 4 and 5
 *
 * LICENSE: This source file is subject to version 3.0 of the PHP license
 * that is available through the world-wide-web at the following URI:
 * http://www.php.net/license/3_0.txt.  If you did not receive a copy of
 * the PHP License and are unable to obtain it through the web, please
 * send a note to license@php.net so we can mail you a copy immediately.
 *
 * @category   Database
 * @package    DB
 * @author     Stig Bakken <ssb@php.net>
 * @author     Daniel Convissor <danielc@php.net>
 * @copyright  1997-2005 The PHP Group
 * @license    http://www.php.net/license/3_0.txt  PHP License 3.0
 * @version    CVS: $Id: mysql.php 32 2005-08-01 06:21:02Z dancoulter $
 * @link       http://pear.php.net/package/DB
 */

/**
 * Obtain the DB_common class so it can be extended from
 */
require_once 'DB/common.php';

/**
 * The methods PEAR DB uses to interact with PHP's mysql extension
 * for interacting with MySQL databases
 *
 * These methods overload the ones declared in DB_common.
 *
 * @category   Database
 * @package    DB
 * @author     Stig Bakken <ssb@php.net>
 * @author     Daniel Convissor <danielc@php.net>
 * @copyright  1997-2005 The PHP Group
 * @license    http://www.php.net/license/3_0.txt  PHP License 3.0
 * @version    Release: @package_version@
 * @link       http://pear.php.net/package/DB
 */
class DB_mysql extends DB_common
{
    // {{{ properties

    /**
     * The DB driver type (mysql, oci8, odbc, etc.)
     * @var string
     */
    var $phptype = 'mysql';

    /**
     * The database syntax variant to be used (db2, access, etc.), if any
     * @var string
     */
    var $dbsyntax = 'mysql';

    /**
     * The capabilities of this DB implementation
     *
     * The 'new_link' element contains the PHP version that first provided
     * new_link support for this DBMS.  Contains false if it's unsupported.
     *
     * Meaning of the 'limit' element:
     *   + 'emulate' = emulate with fetch row by number
     *   + 'alter'   = alter the query
     *   + false     = skip rows
     *
     * @var array
     */
    var $features = array(
        'limit'         => 'alter',
        'new_link'      => '4.2.0',
        'numrows'       => true,
        'pconnect'      => true,
        'prepare'       => false,
        'ssl'           => false,
        'transactions'  => true,
    );

    /**
     * A mapping of native error codes to DB error codes
     * @var array
     */
    var $errorcode_map = array(
        1004 => DB_ERROR_CANNOT_CREATE,
        1005 => DB_ERROR_CANNOT_CREATE,
        1006 => DB_ERROR_CANNOT_CREATE,
        1007 => DB_ERROR_ALREADY_EXISTS,
        1008 => DB_ERROR_CANNOT_DROP,
        1022 => DB_ERROR_ALREADY_EXISTS,
        1044 => DB_ERROR_ACCESS_VIOLATION,
        1046 => DB_ERROR_NODBSELECTED,
        1048 => DB_ERROR_CONSTRAINT,
        1049 => DB_ERROR_NOSUCHDB,
        1050 => DB_ERROR_ALREADY_EXISTS,
        1051 => DB_ERROR_NOSUCHTABLE,
        1054 => DB_ERROR_NOSUCHFIELD,
        1061 => DB_ERROR_ALREADY_EXISTS,
        1062 => DB_ERROR_ALREADY_EXISTS,
        1064 => DB_ERROR_SYNTAX,
        1091 => DB_ERROR_NOT_FOUND,
        1100 => DB_ERROR_NOT_LOCKED,
        1136 => DB_ERROR_VALUE_COUNT_ON_ROW,
        1142 => DB_ERROR_ACCESS_VIOLATION,
        1146 => DB_ERROR_NOSUCHTABLE,
        1216 => DB_ERROR_CONSTRAINT,
        1217 => DB_ERROR_CONSTRAINT,
    );

    /**
     * The raw database connection created by PHP
     * @var resource
     */
    var $connection;

    /**
     * The DSN information for connecting to a database
     * @var array
     */
    var $dsn = array();


    /**
     * Should data manipulation queries be committed automatically?
     * @var bool
     * @access private
     */
    var $autocommit = true;

    /**
     * The quantity of transactions begun
     *
     * {@internal  While this is private, it can't actually be designated
     * private in PHP 5 because it is directly accessed in the test suite.}}
     *
     * @var integer
     * @access private
     */
    var $transaction_opcount = 0;

    /**
     * The database specified in the DSN
     *
     * It's a fix to allow calls to different databases in the same script.
     *
     * @var string
     * @access private
     */
    var $_db = '';


    // }}}
    // {{{ constructor

    /**
     * This constructor calls <kbd>$this->DB_common()</kbd>
     *
     * @return void
     */
    function DB_mysql()
    {
        $this->DB_common();
    }

    // }}}
    // {{{ connect()

    /**
     * Connect to the database server, log in and open the database
     *
     * Don't call this method directly.  Use DB::connect() instead.
     *
     * PEAR DB's mysql driver supports the following extra DSN options:
     *   + new_link      If set to true, causes subsequent calls to connect()
     *                    to return a new connection link instead of the
     *                    existing one.  WARNING: this is not portable to
     *                    other DBMS's. Available since PEAR DB 1.7.0.
     *   + client_flags  Any combination of MYSQL_CLIENT_* constants.
     *                    Only used if PHP is at version 4.3.0 or greater.
     *                    Available since PEAR DB 1.7.0.
     *
     * @param array $dsn         the data source name
     * @param bool  $persistent  should the connection be persistent?
     *
     * @return int  DB_OK on success. A DB_Error object on failure.
     */
    function connect($dsn, $persistent = false)
    {
        if (!PEAR::loadExtension('mysql')) {
            return $this->raiseError(DB_ERROR_EXTENSION_NOT_FOUND);
        }

        $this->dsn = $dsn;
        if ($dsn['dbsyntax']) {
            $this->dbsyntax = $dsn['dbsyntax'];
        }

        $params = array();
        if ($dsn['protocol'] && $dsn['protocol'] == 'unix') {
            $params[0] = ':' . $dsn['socket'];
        } else {
            $params[0] = $dsn['hostspec'] ? $dsn['hostspec']
                         : 'localhost';
            if ($dsn['port']) {
                $params[0] .= ':' . $dsn['port'];
            }
        }
        $params[] = $dsn['username'] ? $dsn['username'] : null;
        $params[] = $dsn['password'] ? $dsn['password'] : null;

        if (!$persistent) {
            if (isset($dsn['new_link'])
                && ($dsn['new_link'] == 'true' || $dsn['new_link'] === true))
            {
                $params[] = true;
            } else {
                $params[] = false;
            }
        }
        if (version_compare(phpversion(), '4.3.0', '>=')) {
            $params[] = isset($dsn['client_flags'])
                        ? $dsn['client_flags'] : null;
        }

        $connect_function = $persistent ? 'mysql_pconnect' : 'mysql_connect';

        $ini = ini_get('track_errors');
        $php_errormsg = '';
        if ($ini) {
            $this->connection = @call_user_func_array($connect_function,
                                                      $params);
        } else {
            ini_set('track_errors', 1);
            $this->connection = @call_user_func_array($connect_function,
                                                      $params);
            ini_set('track_errors', $ini);
        }

        if (!$this->connection) {
            if (($err = @mysql_error()) != '') {
                return $this->raiseError(DB_ERROR_CONNECT_FAILED,
                                         null, null, null, 
                                         $err);
            } else {
                return $this->raiseError(DB_ERROR_CONNECT_FAILED,
                                         null, null, null,
                                         $php_errormsg);
            }
        }

        if ($dsn['database']) {
            if (!@mysql_select_db($dsn['database'], $this->connection)) {
                return $this->mysqlRaiseError();
            }
            $this->_db = $dsn['database'];
        }

        return DB_OK;
    }

    // }}}
    // {{{ disconnect()

    /**
     * Disconnects from the database server
     *
     * @return bool  TRUE on success, FALSE on failure
     */
    function disconnect()
    {
        $ret = @mysql_close($this->connection);
        $this->connection = null;
        return $ret;
    }

    // }}}
    // {{{ simpleQuery()

    /**
     * Sends a query to the database server
     *
     * Generally uses mysql_query().  If you want to use
     * mysql_unbuffered_query() set the "result_buffering" option to 0 using
     * setOptions().  This option was added in Release 1.7.0.
     *
     * @param string  the SQL query string
     *
     * @return mixed  + a PHP result resrouce for successful SELECT queries
     *                + the DB_OK constant for other successful queries
     *                + a DB_Error object on failure
     */
    function simpleQuery($query)
    {
        $ismanip = DB::isManip($query);
        $this->last_query = $query;
        $query = $this->modifyQuery($query);
        if ($this->_db) {
            if (!@mysql_select_db($this->_db, $this->connection)) {
                return $this->mysqlRaiseError(DB_ERROR_NODBSELECTED);
            }
        }
        if (!$this->autocommit && $ismanip) {
            if ($this->transaction_opcount == 0) {
                $result = @mysql_query('SET AUTOCOMMIT=0', $this->connection);
                $result = @mysql_query('BEGIN', $this->connection);
                if (!$result) {
                    return $this->mysqlRaiseError();
                }
            }
            $this->transaction_opcount++;
        }
        if (!$this->options['result_buffering']) {
            $result = @mysql_unbuffered_query($query, $this->connection);
        } else {
            $result = @mysql_query($query, $this->connection);
        }
        if (!$result) {
            return $this->mysqlRaiseError();
        }
        if (is_resource($result)) {
            return $result;
        }
        return DB_OK;
    }

    // }}}
    // {{{ nextResult()

    /**
     * Move the internal mysql result pointer to the next available result
     *
     * This method has not been implemented yet.
     *
     * @param a valid sql result resource
     *
     * @return false
     */
    function nextResult($result)
    {
        return false;
    }

    // }}}
    // {{{ fetchInto()

    /**
     * Places a row from the result set into the given array
     *
     * Formating of the array and the data therein are configurable.
     * See DB_result::fetchInto() for more information.
     *
     * This method is not meant to be called directly.  Use
     * DB_result::fetchInto() instead.  It can't be declared "protected"
     * because DB_result is a separate object.
     *
     * @param resource $result    the query result resource
     * @param array    $arr       the referenced array to put the data in
     * @param int      $fetchmode how the resulting array should be indexed
     * @param int      $rownum    the row number to fetch (0 = first row)
     *
     * @return mixed  DB_OK on success, NULL when the end of a result set is
     *                 reached or on failure
     *
     * @see DB_result::fetchInto()
     */
    function fetchInto($result, &$arr, $fetchmode, $rownum = null)
    {
        if ($rownum !== null) {
            if (!@mysql_data_seek($result, $rownum)) {
                return null;
            }
        }
        if ($fetchmode & DB_FETCHMODE_ASSOC) {
            $arr = @mysql_fetch_array($result, MYSQL_ASSOC);
            if ($this->options['portability'] & DB_PORTABILITY_LOWERCASE && $arr) {
                $arr = array_change_key_case($arr, CASE_LOWER);
            }
        } else {
            $arr = @mysql_fetch_row($result);
        }
        if (!$arr) {
            return null;
        }
        if ($this->options['portability'] & DB_PORTABILITY_RTRIM) {
            /*
             * Even though this DBMS already trims output, we do this because
             * a field might have intentional whitespace at the end that
             * gets removed by DB_PORTABILITY_RTRIM under another driver.
             */
            $this->_rtrimArrayValues($arr);
        }
        if ($this->options['portability'] & DB_PORTABILITY_NULL_TO_EMPTY) {
            $this->_convertNullArrayValuesToEmpty($arr);
        }
        return DB_OK;
    }

    // }}}
    // {{{ freeResult()

    /**
     * Deletes the result set and frees the memory occupied by the result set
     *
     * This method is not meant to be called directly.  Use
     * DB_result::free() instead.  It can't be declared "protected"
     * because DB_result is a separate object.
     *
     * @param resource $result  PHP's query result resource
     *
     * @return bool  TRUE on success, FALSE if $result is invalid
     *
     * @see DB_result::free()
     */
    function freeResult($result)
    {
        return @mysql_free_result($result);
    }

    // }}}
    // {{{ numCols()

    /**
     * Gets the number of columns in a result set
     *
     * This method is not meant to be called directly.  Use
     * DB_result::numCols() instead.  It can't be declared "protected"
     * because DB_result is a separate object.
     *
     * @param resource $result  PHP's query result resource
     *
     * @return int  the number of columns.  A DB_Error object on failure.
     *
     * @see DB_result::numCols()
     */
    function numCols($result)
    {
        $cols = @mysql_num_fields($result);
        if (!$cols) {
            return $this->mysqlRaiseError();
        }
        return $cols;
    }

    // }}}
    // {{{ numRows()

    /**
     * Gets the number of rows in a result set
     *
     * This method is not meant to be called directly.  Use
     * DB_result::numRows() instead.  It can't be declared "protected"
     * because DB_result is a separate object.
     *
     * @param resource $result  PHP's query result resource
     *
     * @return int  the number of rows.  A DB_Error object on failure.
     *
     * @see DB_result::numRows()
     */
    function numRows($result)
    {
        $rows = @mysql_num_rows($result);
        if ($rows === null) {
            return $this->mysqlRaiseError();
        }
        return $rows;
    }

    // }}}
    // {{{ autoCommit()

    /**
     * Enables or disables automatic commits
     *
     * @param bool $onoff  true turns it on, false turns it off
     *
     * @return int  DB_OK on success.  A DB_Error object if the driver
     *               doesn't support auto-committing transactions.
     */
    function autoCommit($onoff = false)
    {
        // XXX if $this->transaction_opcount > 0, we should probably
        // issue a warning here.
        $this->autocommit = $onoff ? true : false;
        return DB_OK;
    }

    // }}}
    // {{{ commit()

    /**
     * Commits the current transaction
     *
     * @return int  DB_OK on success.  A DB_Error object on failure.
     */
    function commit()
    {
        if ($this->transaction_opcount > 0) {
            if ($this->_db) {
                if (!@mysql_select_db($this->_db, $this->connection)) {
                    return $this->mysqlRaiseError(DB_ERROR_NODBSELECTED);
                }
            }
            $result = @mysql_query('COMMIT', $this->connection);
            $result = @mysql_query('SET AUTOCOMMIT=1', $this->connection);
            $this->transaction_opcount = 0;
            if (!$result) {
                return $this->mysqlRaiseError();
            }
        }
        return DB_OK;
    }

    // }}}
    // {{{ rollback()

    /**
     * Reverts the current transaction
     *
     * @return int  DB_OK on success.  A DB_Error object on failure.
     */
    function rollback()
    {
        if ($this->transaction_opcount > 0) {
            if ($this->_db) {
                if (!@mysql_select_db($this->_db, $this->connection)) {
                    return $this->mysqlRaiseError(DB_ERROR_NODBSELECTED);
                }
            }
            $result = @mysql_query('ROLLBACK', $this->connection);
            $result = @mysql_query('SET AUTOCOMMIT=1', $this->connection);
            $this->transaction_opcount = 0;
            if (!$result) {
                return $this->mysqlRaiseError();
            }
        }
        return DB_OK;
    }

    // }}}
    // {{{ affectedRows()

    /**
     * Determines the number of rows affected by a data maniuplation query
     *
     * 0 is returned for queries that don't manipulate data.
     *
     * @return int  the number of rows.  A DB_Error object on failure.
     */
    function affectedRows()
    {
        if (DB::isManip($this->last_query)) {
            return @mysql_affected_rows($this->connection);
        } else {
            return 0;
        }
     }

    // }}}
    // {{{ nextId()

    /**
     * Returns the next free id in a sequence
     *
     * @param string  $seq_name  name of the sequence
     * @param boolean $ondemand  when true, the seqence is automatically
     *                            created if it does not exist
     *
     * @return int  the next id number in the sequence.
     *               A DB_Error object on failure.
     *
     * @see DB_common::nextID(), DB_common::getSequenceName(),
     *      DB_mysql::createSequence(), DB_mysql::dropSequence()
     */
    function nextId($seq_name, $ondemand = true)
    {
        $seqname = $this->getSequenceName($seq_name);
        do {
            $repeat = 0;
            $this->pushErrorHandling(PEAR_ERROR_RETURN);
            $result = $this->query("UPDATE ${seqname} ".
                                   'SET id=LAST_INSERT_ID(id+1)');
            $this->popErrorHandling();
            if ($result === DB_OK) {
                // COMMON CASE
                $id = @mysql_insert_id($this->connection);
                if ($id != 0) {
                    return $id;
                }
                // EMPTY SEQ TABLE
                // Sequence table must be empty for some reason, so fill
                // it and return 1 and obtain a user-level lock
                $result = $this->getOne("SELECT GET_LOCK('${seqname}_lock',10)");
                if (DB::isError($result)) {
                    return $this->raiseError($result);
                }
                if ($result == 0) {
                    // Failed to get the lock
                    return $this->mysqlRaiseError(DB_ERROR_NOT_LOCKED);
                }

                // add the default value
                $result = $this->query("REPLACE INTO ${seqname} (id) VALUES (0)");
                if (DB::isError($result)) {
                    return $this->raiseError($result);
                }

                // Release the lock
                $result = $this->getOne('SELECT RELEASE_LOCK('
                                        . "'${seqname}_lock')");
                if (DB::isError($result)) {
                    return $this->raiseError($result);
                }
                // We know what the result will be, so no need to try again
                return 1;

            } elseif ($ondemand && DB::isError($result) &&
                $result->getCode() == DB_ERROR_NOSUCHTABLE)
            {
                // ONDEMAND TABLE CREATION
                $result = $this->createSequence($seq_name);
                if (DB::isError($result)) {
                    return $this->raiseError($result);
                } else {
                    $repeat = 1;
                }

            } elseif (DB::isError($result) &&
                      $result->getCode() == DB_ERROR_ALREADY_EXISTS)
            {
                // BACKWARDS COMPAT
                // see _BCsequence() comment
                $result = $this->_BCsequence($seqname);
                if (DB::isError($result)) {
                    return $this->raiseError($result);
                }
                $repeat = 1;
            }
        } while ($repeat);

        return $this->raiseError($result);
    }

    // }}}
    // {{{ createSequence()

    /**
     * Creates a new sequence
     *
     * @param string $seq_name  name of the new sequence
     *
     * @return int  DB_OK on success.  A DB_Error object on failure.
     *
     * @see DB_common::createSequence(), DB_common::getSequenceName(),
     *      DB_mysql::nextID(), DB_mysql::dropSequence()
     */
    function createSequence($seq_name)
    {
        $seqname = $this->getSequenceName($seq_name);
        $res = $this->query('CREATE TABLE ' . $seqname
                            . ' (id INTEGER UNSIGNED AUTO_INCREMENT NOT NULL,'
                            . ' PRIMARY KEY(id))');
        if (DB::isError($res)) {
            return $res;
        }
        // insert yields value 1, nextId call will generate ID 2
        $res = $this->query("INSERT INTO ${seqname} (id) VALUES (0)");
        if (DB::isError($res)) {
            return $res;
        }
        // so reset to zero
        return $this->query("UPDATE ${seqname} SET id = 0");
    }

    // }}}
    // {{{ dropSequence()

    /**
     * Deletes a sequence
     *
     * @param string $seq_name  name of the sequence to be deleted
     *
     * @return int  DB_OK on success.  A DB_Error object on failure.
     *
     * @see DB_common::dropSequence(), DB_common::getSequenceName(),
     *      DB_mysql::nextID(), DB_mysql::createSequence()
     */
    function dropSequence($seq_name)
    {
        return $this->query('DROP TABLE ' . $this->getSequenceName($seq_name));
    }

    // }}}
    // {{{ _BCsequence()

    /**
     * Backwards compatibility with old sequence emulation implementation
     * (clean up the dupes)
     *
     * @param string $seqname  the sequence name to clean up
     *
     * @return bool  true on success.  A DB_Error object on failure.
     *
     * @access private
     */
    function _BCsequence($seqname)
    {
        // Obtain a user-level lock... this will release any previous
        // application locks, but unlike LOCK TABLES, it does not abort
        // the current transaction and is much less frequently used.
        $result = $this->getOne("SELECT GET_LOCK('${seqname}_lock',10)");
        if (DB::isError($result)) {
            return $result;
        }
        if ($result == 0) {
            // Failed to get the lock, can't do the conversion, bail
            // with a DB_ERROR_NOT_LOCKED error
            return $this->mysqlRaiseError(DB_ERROR_NOT_LOCKED);
        }

        $highest_id = $this->getOne("SELECT MAX(id) FROM ${seqname}");
        if (DB::isError($highest_id)) {
            return $highest_id;
        }
        // This should kill all rows except the highest
        // We should probably do something if $highest_id isn't
        // numeric, but I'm at a loss as how to handle that...
        $result = $this->query('DELETE FROM ' . $seqname
                               . " WHERE id <> $highest_id");
        if (DB::isError($result)) {
            return $result;
        }

        // If another thread has been waiting for this lock,
        // it will go thru the above procedure, but will have no
        // real effect
        $result = $this->getOne("SELECT RELEASE_LOCK('${seqname}_lock')");
        if (DB::isError($result)) {
            return $result;
        }
        return true;
    }

    // }}}
    // {{{ quoteIdentifier()

    /**
     * Quotes a string so it can be safely used as a table or column name
     *
     * MySQL can't handle the backtick character (<kbd>`</kbd>) in
     * table or column names.
     *
     * @param string $str  identifier name to be quoted
     *
     * @return string  quoted identifier string
     *
     * @see DB_common::quoteIdentifier()
     * @since Method available since Release 1.6.0
     */
    function quoteIdentifier($str)
    {
        return '`' . $str . '`';
    }

    // }}}
    // {{{ quote()

    /**
     * @deprecated  Deprecated in release 1.6.0
     */
    function quote($str)
    {
        return $this->quoteSmart($str);
    }

    // }}}
    // {{{ escapeSimple()

    /**
     * Escapes a string according to the current DBMS's standards
     *
     * @param string $str  the string to be escaped
     *
     * @return string  the escaped string
     *
     * @see DB_common::quoteSmart()
     * @since Method available since Release 1.6.0
     */
    function escapeSimple($str)
    {
        if (function_exists('mysql_real_escape_string')) {
            return @mysql_real_escape_string($str, $this->connection);
        } else {
            return @mysql_escape_string($str);
        }
    }

    // }}}
    // {{{ modifyQuery()

    /**
     * Changes a query string for various DBMS specific reasons
     *
     * This little hack lets you know how many rows were deleted
     * when running a "DELETE FROM table" query.  Only implemented
     * if the DB_PORTABILITY_DELETE_COUNT portability option is on.
     *
     * @param string $query  the query string to modify
     *
     * @return string  the modified query string
     *
     * @access protected
     * @see DB_common::setOption()
     */
    function modifyQuery($query)
    {
        if ($this->options['portability'] & DB_PORTABILITY_DELETE_COUNT) {
            // "DELETE FROM table" gives 0 affected rows in MySQL.
            // This little hack lets you know how many rows were deleted.
            if (preg_match('/^\s*DELETE\s+FROM\s+(\S+)\s*$/i', $query)) {
                $query = preg_replace('/^\s*DELETE\s+FROM\s+(\S+)\s*$/',
                                      'DELETE FROM \1 WHERE 1=1', $query);
            }
        }
        return $query;
    }

    // }}}
    // {{{ modifyLimitQuery()

    /**
     * Adds LIMIT clauses to a query string according to current DBMS standards
     *
     * @param string $query   the query to modify
     * @param int    $from    the row to start to fetching (0 = the first row)
     * @param int    $count   the numbers of rows to fetch
     * @param mixed  $params  array, string or numeric data to be used in
     *                         execution of the statement.  Quantity of items
     *                         passed must match quantity of placeholders in
     *                         query:  meaning 1 placeholder for non-array
     *                         parameters or 1 placeholder per array element.
     *
     * @return string  the query string with LIMIT clauses added
     *
     * @access protected
     */
    function modifyLimitQuery($query, $from, $count, $params = array())
    {
        if (DB::isManip($query)) {
            return $query . " LIMIT $count";
        } else {
            return $query . " LIMIT $from, $count";
        }
    }

    // }}}
    // {{{ mysqlRaiseError()

    /**
     * Produces a DB_Error object regarding the current problem
     *
     * @param int $errno  if the error is being manually raised pass a
     *                     DB_ERROR* constant here.  If this isn't passed
     *                     the error information gathered from the DBMS.
     *
     * @return object  the DB_Error object
     *
     * @see DB_common::raiseError(),
     *      DB_mysql::errorNative(), DB_common::errorCode()
     */
    function mysqlRaiseError($errno = null)
    {
        if ($errno === null) {
            if ($this->options['portability'] & DB_PORTABILITY_ERRORS) {
                $this->errorcode_map[1022] = DB_ERROR_CONSTRAINT;
                $this->errorcode_map[1048] = DB_ERROR_CONSTRAINT_NOT_NULL;
                $this->errorcode_map[1062] = DB_ERROR_CONSTRAINT;
            } else {
                // Doing this in case mode changes during runtime.
                $this->errorcode_map[1022] = DB_ERROR_ALREADY_EXISTS;
                $this->errorcode_map[1048] = DB_ERROR_CONSTRAINT;
                $this->errorcode_map[1062] = DB_ERROR_ALREADY_EXISTS;
            }
            $errno = $this->errorCode(mysql_errno($this->connection));
        }
        return $this->raiseError($errno, null, null, null,
                                 @mysql_errno($this->connection) . ' ** ' .
                                 @mysql_error($this->connection));
    }

    // }}}
    // {{{ errorNative()

    /**
     * Gets the DBMS' native error code produced by the last query
     *
     * @return int  the DBMS' error code
     */
    function errorNative()
    {
        return @mysql_errno($this->connection);
    }

    // }}}
    // {{{ tableInfo()

    /**
     * Returns information about a table or a result set
     *
     * @param object|string  $result  DB_result object from a query or a
     *                                 string containing the name of a table.
     *                                 While this also accepts a query result
     *                                 resource identifier, this behavior is
     *                                 deprecated.
     * @param int            $mode    a valid tableInfo mode
     *
     * @return array  an associative array with the information requested.
     *                 A DB_Error object on failure.
     *
     * @see DB_common::tableInfo()
     */
    function tableInfo($result, $mode = null)
    {
        if (is_string($result)) {
            /*
             * Probably received a table name.
             * Create a result resource identifier.
             */
            $id = @mysql_list_fields($this->dsn['database'],
                                     $result, $this->connection);
            $got_string = true;
        } elseif (isset($result->result)) {
            /*
             * Probably received a result object.
             * Extract the result resource identifier.
             */
            $id = $result->result;
            $got_string = false;
        } else {
            /*
             * Probably received a result resource identifier.
             * Copy it.
             * Deprecated.  Here for compatibility only.
             */
            $id = $result;
            $got_string = false;
        }

        if (!is_resource($id)) {
            return $this->mysqlRaiseError(DB_ERROR_NEED_MORE_DATA);
        }

        if ($this->options['portability'] & DB_PORTABILITY_LOWERCASE) {
            $case_func = 'strtolower';
        } else {
            $case_func = 'strval';
        }

        $count = @mysql_num_fields($id);
        $res   = array();

        if ($mode) {
            $res['num_fields'] = $count;
        }

        for ($i = 0; $i < $count; $i++) {
            $res[$i] = array(
                'table' => $case_func(@mysql_field_table($id, $i)),
                'name'  => $case_func(@mysql_field_name($id, $i)),
                'type'  => @mysql_field_type($id, $i),
                'len'   => @mysql_field_len($id, $i),
                'flags' => @mysql_field_flags($id, $i),
            );
            if ($mode & DB_TABLEINFO_ORDER) {
                $res['order'][$res[$i]['name']] = $i;
            }
            if ($mode & DB_TABLEINFO_ORDERTABLE) {
                $res['ordertable'][$res[$i]['table']][$res[$i]['name']] = $i;
            }
        }

        // free the result only if we were called on a table
        if ($got_string) {
            @mysql_free_result($id);
        }
        return $res;
    }

    // }}}
    // {{{ getSpecialQuery()

    /**
     * Obtains the query string needed for listing a given type of objects
     *
     * @param string $type  the kind of objects you want to retrieve
     *
     * @return string  the SQL query string or null if the driver doesn't
     *                  support the object type requested
     *
     * @access protected
     * @see DB_common::getListOf()
     */
    function getSpecialQuery($type)
    {
        switch ($type) {
            case 'tables':
                return 'SHOW TABLES';
            case 'users':
                return 'SELECT DISTINCT User FROM mysql.user';
            case 'databases':
                return 'SHOW DATABASES';
            default:
                return null;
        }
    }

    // }}}

}

/*
 * Local variables:
 * tab-width: 4
 * c-basic-offset: 4
 * End:
 */

?>