This file is indexed.

/usr/share/perl5/Alzabo/Driver.pm is in libalzabo-perl 0.92-4.

This file is owned by root:root, with mode 0o644.

The actual contents of the file can be viewed below.

   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
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
package Alzabo::Driver;

use strict;
use vars qw($VERSION);

use Alzabo::Exceptions;

use Class::Factory::Util;
use DBI;
use Params::Validate qw( validate validate_pos UNDEF SCALAR ARRAYREF );
Params::Validate::validation_options( on_fail => sub { Alzabo::Exception::Params->throw( error => join '', @_ ) } );

$VERSION = 2.0;

1;

sub new
{
    shift;
    my %p = @_;

    eval "use Alzabo::Driver::$p{rdbms}";
    Alzabo::Exception::Eval->throw( error => $@ ) if $@;

    my $self = "Alzabo::Driver::$p{rdbms}"->new(@_);

    $self->{schema} = $p{schema};

    return $self;
}

sub available { __PACKAGE__->subclasses }

sub _ensure_valid_dbh
{
    my $self = shift;

    unless ( $self->{dbh} )
    {
        my $sub = (caller(1))[3];
        Alzabo::Exception::Driver->throw( error => "Cannot call $sub before calling connect." );
    }

    $self->{dbh} = $self->_dbi_connect( $self->{connect_params} )
        if $$ != $self->{connect_pid};
}

sub quote
{
    my $self = shift;

    $self->_ensure_valid_dbh;

    return $self->{dbh}->quote(@_);
}

sub quote_identifier
{
    my $self = shift;

    $self->_ensure_valid_dbh;

    return $self->{dbh}->quote_identifier(@_);
}

sub rows
{
    my $self = shift;

    $self->_ensure_valid_dbh;

    my %p = @_;

    my $sth = $self->_prepare_and_execute(%p);

    my @data;
    eval
    {
        my @row;
        $sth->bind_columns( \ (@row[ 0..$#{ $sth->{NAME_lc} } ] ) );

        push @data, [@row] while $sth->fetch;

        $sth->finish;
    };
    if ($@)
    {
        my @bind = exists $p{bind} ? ( ref $p{bind} ? $p{bind} : [$p{bind}] ) : ();
        Alzabo::Exception::Driver->throw( error => $@,
                                          sql => $p{sql},
                                          bind => \@bind );
    }

    return wantarray ? @data : $data[0];
}

sub rows_hashref
{
    my $self = shift;
    my %p = @_;

    $self->_ensure_valid_dbh;

    my $sth = $self->_prepare_and_execute(%p);

    my @data;

    eval
    {
        my %hash;
        $sth->bind_columns( \ ( @hash{ @{ $sth->{NAME_uc} } } ) );

        push @data, {%hash} while $sth->fetch;

        $sth->finish;
    };
    if ($@)
    {
        my @bind = exists $p{bind} ? ( ref $p{bind} ? $p{bind} : [$p{bind}] ) : ();
        Alzabo::Exception::Driver->throw( error => $@,
                                          sql => $p{sql},
                                          bind => \@bind );
    }

    return @data;
}

sub one_row
{
    my $self = shift;
    my %p = @_;

    $self->_ensure_valid_dbh;

    my $sth = $self->_prepare_and_execute(%p);

    my @row;
    eval
    {
        @row = $sth->fetchrow_array;
        $sth->finish;
    };
    if ($@)
    {
        my @bind = exists $p{bind} ? ( ref $p{bind} ? $p{bind} : [$p{bind}] ) : ();
        Alzabo::Exception::Driver->throw( error => $@,
                                          sql => $p{sql},
                                          bind => \@bind );
    }

    return wantarray ? @row : $row[0];
}

sub one_row_hash
{
    my $self = shift;
    my %p = @_;

    $self->_ensure_valid_dbh;

    my $sth = $self->_prepare_and_execute(%p);

    my %hash;
    eval
    {
        my @row = $sth->fetchrow_array;
        @hash{ @{ $sth->{NAME_uc} } } = @row if @row;
        $sth->finish;
    };
    if ($@)
    {
        my @bind = exists $p{bind} ? ( ref $p{bind} ? $p{bind} : [$p{bind}] ) : ();
        Alzabo::Exception::Driver->throw( error => $@,
                                          sql => $p{sql},
                                          bind => \@bind );
    }

    return %hash;
}

sub column
{
    my $self = shift;
    my %p = @_;

    $self->_ensure_valid_dbh;

    my $sth = $self->_prepare_and_execute(%p);

    my @data;
    eval
    {
        my @row;
        $sth->bind_columns( \ (@row[ 0..$#{ $sth->{NAME_lc} } ] ) );
        push @data, $row[0] while ($sth->fetch);
        $sth->finish;
    };
    if ($@)
    {
        my @bind = exists $p{bind} ? ( ref $p{bind} ? $p{bind} : [$p{bind}] ) : ();
        Alzabo::Exception::Driver->throw( error => $@,
                                          sql => $p{sql},
                                          bind => \@bind );
    }

    return wantarray ? @data : $data[0];
}

use constant _PREPARE_AND_EXECUTE_SPEC => { sql => { type => SCALAR },
                                            bind => { type => UNDEF | SCALAR | ARRAYREF,
                                                      optional => 1 },
                                          };

sub _prepare_and_execute
{
    my $self = shift;

    validate( @_, _PREPARE_AND_EXECUTE_SPEC );
    my %p = @_;

    Alzabo::Exception::Driver->throw( error => "Attempt to access the database without database handle.  Was ->connect called?" )
        unless $self->{dbh};

    my @bind = exists $p{bind} ? ( ref $p{bind} ? @{ $p{bind} } : $p{bind} ) : ();

    my $sth;
    eval
    {
        $sth = $self->{dbh}->prepare( $p{sql} );
        $sth->execute(@bind);
    };
    if ($@)
    {
        Alzabo::Exception::Driver->throw( error => $@,
                                          sql => $p{sql},
                                          bind => \@bind );
    }

    return $sth;
}

sub do
{
    my $self = shift;
    my %p = @_;

    $self->_ensure_valid_dbh;

    my $sth = $self->_prepare_and_execute(%p);

    my $rows;
    eval
    {
        $rows = $sth->rows;
        $sth->finish;
    };
    if ($@)
    {
        my @bind = exists $p{bind} ? ( ref $p{bind} ? $p{bind} : [$p{bind}] ) : ();
        Alzabo::Exception::Driver->throw( error => $@,
                                          sql => $p{sql},
                                          bind => \@bind );
    }

    return $rows;
}

sub tables
{
    my $self = shift;

    $self->_ensure_valid_dbh;

    my @t = eval {  $self->{dbh}->tables( '', '', '%', 'table' ); };
    Alzabo::Exception::Driver->throw( error => $@ ) if $@;

    return @t;
}

sub schemas
{
    my $self = shift;

    shift()->_virtual;
}

sub _make_dbh
{
    my $self = shift;

    return $self->_dbi_connect( $self->_connect_params(@_) );
}

sub _dbi_connect
{
    my $self = shift;
    my $connect = shift;

    my $dbh = eval { DBI->connect(@$connect) };

    Alzabo::Exception::Driver->throw( error => $@ ) if $@;
    Alzabo::Exception::Driver->throw( error => "Unable to connect to database\n" ) unless $dbh;

    $self->{connect_params} = $connect;
    $self->{connect_pid} = $$;

    return $dbh;
}

sub statement
{
    my $self = shift;

    $self->_ensure_valid_dbh;

    return Alzabo::DriverStatement->new( dbh => $self->{dbh},
                                         @_ );
}

sub statement_no_execute
{
    my $self = shift;

    $self->_ensure_valid_dbh;

    return Alzabo::DriverStatement->new_no_execute( dbh => $self->{dbh},
                                                    @_ );
}

sub func
{
    my $self = shift;

    $self->_ensure_valid_dbh;

    my @r;
    eval
    {
        if (wantarray)
        {
            @r = $self->{dbh}->func(@_);
            return @r;
        }
        else
        {
            $r[0] = $self->{dbh}->func(@_);
            return $r[0];
        }
    };
    Alzabo::Exception::Driver->throw( error => $self->{dbh}->errstr )
        if $self->{dbh}->errstr;
}

sub DESTROY
{
    my $self = shift;
    $self->disconnect;
}

sub disconnect
{
    my $self = shift;
    $self->{dbh}->disconnect if $self->{dbh};
    delete $self->{dbh};
}

sub handle
{
    my $self = shift;

    if (@_)
    {
        validate_pos( @_, { isa => 'DBI::db' } );
        $self->{dbh} = shift;
    }

    return $self->{dbh};
}

sub rdbms_version
{
    shift()->_virtual;
}

sub connect
{
    shift()->_virtual;
}

sub supports_referential_integrity
{
    shift()->_virtual;
}

sub create_database
{
    shift()->_virtual;
}

sub drop_database
{
    shift()->_virtual;
}

sub next_sequence_number
{
    shift()->_virtual;
}

sub begin_work
{
    my $self = shift;

    $self->_ensure_valid_dbh;

    $self->{tran_count} = 0 unless defined $self->{tran_count};

    $self->{dbh}->begin_work if $self->{dbh}->{AutoCommit};

    $self->{tran_count}++;
}

sub rollback
{
    my $self = shift;

    $self->_ensure_valid_dbh;

    $self->{tran_count} = undef;

    eval { $self->{dbh}->rollback unless $self->{dbh}->{AutoCommit} };

    Alzabo::Exception::Driver->throw( error => $@ ) if $@;

    $self->{dbh}->{AutoCommit} = 1;
}

sub commit
{
    my $self = shift;

    $self->_ensure_valid_dbh;

    my $callee = (caller(1))[3];

    # More commits than begin_tran.  Not correct.
    if ( defined $self->{tran_count} )
    {
        $self->{tran_count}--;
    }
    else
    {
        my $caller = (caller(1))[3];
        require Carp;
        Carp::cluck( "$caller called commit without corresponding begin_work call\n" );
    }

    # Don't actually commit until we reach 'uber-commit'
    return if $self->{tran_count};

    unless ( $self->{dbh}->{AutoCommit} )
    {
        $self->{dbh}->commit;
    }
    $self->{dbh}->{AutoCommit} = 1;

    $self->{tran_count} = undef;
}

sub get_last_id
{
    shift()->_virtual;
}

sub driver_id
{
    shift()->_virtual;
}

sub _virtual
{
    my $self = shift;

    my $sub = (caller(1))[3];
    Alzabo::Exception::VirtualMethod->throw( error =>
                                             "$sub is a virtual method and must be subclassed in " . ref $self );
}

package Alzabo::DriverStatement;

use strict;
use vars qw($VERSION);

use Alzabo::Exceptions;

use DBI;

use Params::Validate qw( validate UNDEF SCALAR ARRAYREF );
Params::Validate::validation_options( on_fail => sub { Alzabo::Exception::Params->throw( error => join '', @_ ) } );

$VERSION = '0.1';

sub new
{
    my $self = shift->new_no_execute(@_);

    $self->execute;

    return $self;
}

use constant NEW_NO_EXECUTE_SPEC => { dbh   => { can => 'prepare' },
                                      sql   => { type => SCALAR },
                                      bind  => { type => SCALAR | ARRAYREF,
                                                 optional => 1 },
                                      limit => { type => UNDEF | ARRAYREF,
                                                 optional => 1 },
                                    };

sub new_no_execute
{
    my $proto = shift;
    my $class = ref $proto || $proto;

    my %p = validate( @_, NEW_NO_EXECUTE_SPEC );

    my $self = bless {}, $class;

    $self->{limit} = $p{limit} ? $p{limit}[0] : 0;
    $self->{offset} = $p{limit} && $p{limit}[1] ? $p{limit}[1] : 0;
    $self->{rows_fetched} = 0;

    eval
    {
        $self->{sth} = $p{dbh}->prepare( $p{sql} );

        $self->{bind} = exists $p{bind} ? ( ref $p{bind} ? $p{bind} : [ $p{bind} ] ) : [];
    };

    Alzabo::Exception::Driver->throw( error => $@,
                                      sql => $p{sql},
                                      bind => $self->{bind} ) if $@;

    return $self;
}

sub execute
{
    my $self = shift;

    eval
    {
        $self->{sth}->finish if $self->{sth}->{Active};
        $self->{rows_fetched} = 0;
        $self->{sth}->execute( @_ ? @_ : @{ $self->{bind} } );

        $self->{result} = [];
        $self->{count} = 0;

        $self->{sth}->bind_columns
            ( \ ( @{ $self->{result} }[ 0..$#{ $self->{sth}->{NAME_lc} } ] ) );
    };
    Alzabo::Exception::Driver->throw( error => $@,
                                      sql => $self->{sth}{Statement},
                                      bind => $self->{bind} ) if $@;
}

sub execute_no_result
{
    my $self = shift;

    eval
    {
        $self->{sth}->execute(@_);
    };
    Alzabo::Exception::Driver->throw( error => $@,
                                      sql => $self->{sth}{Statement},
                                      bind => $self->{bind} ) if $@;
}

sub next
{
    my $self = shift;
    my %p = @_;

    return unless $self->{sth}->{Active};

    my $active;
    eval
    {
        do
        {
            $active = $self->{sth}->fetch;
        } while ( $active && $self->{rows_fetched}++ < $self->{offset} );
    };

    Alzabo::Exception::Driver->throw( error => $@,
                                      sql => $self->{sth}{Statement},
                                      bind => $self->{bind} ) if $@;

    return unless $active;

    $self->{count}++;

    return wantarray ? @{ $self->{result} } : $self->{result}[0];
}

sub next_as_hash
{
    my $self = shift;

    return unless $self->{sth}->{Active};

    my $active;
    eval
    {
        do
        {
            $active = $self->{sth}->fetch;
        } while ( $active && $self->{rows_fetched}++ < $self->{offset} );
    };
    Alzabo::Exception::Driver->throw( error => $@,
                                      sql => $self->{sth}{Statement},
                                      bind => $self->{bind} ) if $@;

    return unless $active;

    my %hash;
    @hash{ @{ $self->{sth}->{NAME_lc} } } = @{ $self->{result} };

    $self->{count}++;

    return %hash;
}
*next_hash = \&next_as_hash;

sub all_rows
{
    my $self = shift;

    my @rows;

    while (my @row = $self->next)
    {
        push @rows, @row > 1 ? \@row : $row[0];
    }

    $self->{count} = scalar @rows;

    return @rows;
}

sub all_rows_hash
{
    my $self = shift;

    my @rows;

    while (my %h = $self->next_as_hash)
    {
        push @rows, \%h;
    }

    $self->{count} = scalar @rows;

    return @rows;
}

sub bind
{
    my $self = shift;

    return @{ $self->{bind} };
}

sub count { $_[0]->{count} }

sub DESTROY
{
    my $self = shift;

    local $@;
    eval { $self->{sth}->finish if $self->{sth}; };
    Alzabo::Exception::Driver->throw( error => $@ ) if $@;
}

1;

__END__

=head1 NAME

Alzabo::Driver - Alzabo base class for RDBMS drivers

=head1 SYNOPSIS

  use Alzabo::Driver;

  my $driver = Alzabo::Driver->new( rdbms => 'MySQL',
                                    schema => $schema );

=head1 DESCRIPTION

This is the base class for all Alzabo::Driver modules.  To instantiate
a driver call this class's C<new()> method.  See L<SUBCLASSING
Alzabo::Driver> for information on how to make a driver for the RDBMS
of your choice.

This class throws several, exceptions, one of which,
C<Alzabo::Exception::Driver>, has additional methods not present in
other exception classes.  See L<Alzabo::Exception::Driver METHODS> for
a description of these methods.

=head1 METHODS

=head2 available

Returns a list of names representing the available C<Alzabo::Driver>
subclasses.  Any one of these names would be appropriate as the
"rdbms" parameter for the L<C<< Alzabo::Driver->new
>>|Alzabo::Driver/new> method.

=head2 new

The constructor takes the following parameters:

=over 4

=item * rdbms => $rdbms_name

The name of the RDBMS being used.

=item * schema => C<Alzabo::Schema> object

=back

It returns a new C<Alzabo::Driver> object of the appropriate subclass.

Throws: L<C<Alzabo::Exception::Eval>|Alzabo::Exceptions>

=head2 tables

Returns a list of strings containing the names of the tables in the
database.  See the C<DBI> documentation of the C<DBI-E<gt>tables>
method for more details.

Throws: L<C<Alzabo::Exception::Driver>|Alzabo::Exceptions>

=head2 handle ($optional_dbh)

This method takes one optional parameter, a connected DBI handle.  If
this is given, then this handle is the new handle for the driver.

It returns the active database handle.

Throws: L<C<Alzabo::Exception::Params>|Alzabo::Exceptions>

=head2 Data Retrieval methods

Some of these methods return lists of data (the
L<C<rows>|Alzabo::Driver/rows>,
L<C<rows_hashref>|Alzabo::Driver/rows_hashref>, and
L<C<column>|Alzabo::Driver/column> methods).  With large result sets,
this can use a lot memory as these lists are created in memory before
being returned to the caller.  To avoid this, it may be desirable to
use the functionality provided by the
L<C<Alzabo::DriverStatement>|Alzabo::DriverStatement> class, which
allows you to fetch results one row at a time.

These methods all accept the following parameters:

=over 4

=item * sql => $sql_string

=item * bind => $bind_value or \@bind_values

=item * limit => [ $max, optional $offset ] (optional)

The C<$offset> defaults to 0.

This parameter has no effect for the methods that return only one
row.  For the others, it causes the drivers to skip C<$offset> rows
and then return only C<$max> rows.  This is useful if the RDBMS being
used does not support C<LIMIT> clauses.

=back

=head2 rows

Returns an array of array references containing the data requested.

=head2 rows_hashref

Returns an array of hash references containing the data requested.
The hash reference keys are the columns being selected.  All the key
names are in uppercase.

=head2 one_row

Returns an array or scalar containing the data returned, depending on
context.

=head2 one_row_hash

Returns a hash containing the data requested.  The hash keys are the
columns being selected.  All the key names are in uppercase.

=head2 column

Returns an array containing the values for the first column of each
row returned.

=head2 do

Use this for non-SELECT SQL statements.

Returns the number of rows affected.

Throws: L<C<Alzabo::Exception::Driver>|Alzabo::Exceptions>

=head2 statement

This methods returns a new
L<C<Alzabo::DriverStatement>|Alzabo::DriverStatement> handle, ready to
return data via the L<C<< Alzabo::DriverStatement->next()
>>|Alzabo::DriverStatement/next> or L<C<<
Alzabo::DriverStatement->next_as_hash()
>>|Alzabo::DriverStatement/next_as_hash> methods.

Throws: L<C<Alzabo::Exception::Driver>|Alzabo::Exceptions>

=head2 rdbms_version

Returns the version string of the database backend currently in use.
The form of this string will vary depending on which driver subclass
is being used.

=head2 quote (@strings)

This methods calls the underlying DBI handles C<quote()> method on the
array of strings provided, and returns the quoted versions.

=head2 quote_identifier (@strings)

This methods calls the underlying DBI handles C<quote_identifier()>
method on the array of strings provided, and returns the quoted
versions.

=head1 Alzabo::DriverStatement

This class is a wrapper around C<DBI>'s statement handles.  It finishes
automatically as appropriate so the end user does need not worry about
doing this.

=head2 next

Use this method in a while loop to fetch all the data from a
statement.

Returns an array containing the next row of data for statement or an
empty list if no more data is available.

Throws: L<C<Alzabo::Exception::Driver>|Alzabo::Exceptions>

=head2 next_as_hash

For backwards compatibility, this is also available as C<next_hash()>.

Returns a hash containing the next row of data for statement or an
empty list if no more data is available.  All the keys of the hash
will be lowercased.

Throws: L<C<Alzabo::Exception::Driver>|Alzabo::Exceptions>

=head2 all_rows

If the select for which this statement is cursor was for a single
column (or aggregate value), then this method returns an array
containing each B<remaining> value from the database.

Otherwise, it returns an array of array references, each one
containing a returned row from the database.

Throws: L<C<Alzabo::Exception::Driver>|Alzabo::Exceptions>

=head2 all_rows_hash

Returns an array of hashes, each hash representing a single row
returned from the database.  The hash keys are all in lowercase.

Throws: L<C<Alzabo::Exception::Driver>|Alzabo::Exceptions>

=head2 execute (@bind_values)

Executes the associated statement handle with the given bound
parameters.  If the statement handle is still active (it was
previously executed and has more data left) then its C<finish()>
method will be called first.

Throws: L<C<Alzabo::Exception::Driver>|Alzabo::Exceptions>

=head2 count

Returns the number of rows returned so far.

=head1 Alzabo::Exception::Driver METHODS

In addition to the methods inherited from
L<C<Exception::Class::Base>|Exception::Class::Base>, objects in this
class also contain several methods specific to this subclass.

=head2 sql

Returns the SQL statement in use at the time the error occurred, if
any.

=head2 bind

Returns an array reference contaning the bound parameters for the SQL
statement, if any.

=head1 SUBCLASSING Alzabo::Driver

To create a subclass of C<Alzabo::Driver> for your particular RDBMS is
fairly simple.  First of all, there must be a C<DBD::*> driver for it,
as C<Alzabo::Driver> is built on top of C<DBI>.

Here's a sample header to the module using a fictional RDBMS called FooDB:

 package Alzabo::Driver::FooDB;

 use strict;
 use vars qw($VERSION);

 use Alzabo::Driver;

 use DBI;
 use DBD::FooDB;

 use base qw(Alzabo::Driver);

The next step is to implement a C<new> method and the methods listed
under L<Virtual Methods>.  The C<new> method should look a bit like
this:

 1:  sub new
 2:  {
 3:      my $proto = shift;
 4:      my $class = ref $proto || $proto;
 5:      my %p = @_;
 6:
 7:      my $self = bless {}, $class;
 8:
 9:      return $self;
 10:  }

The hash %p contains any values passed to the
C<Alzabo::Driver-E<gt>new> method by its caller.

Lines 1-7 should probably be copied verbatim into your own C<new>
method.  Line 5 can be deleted if you don't need to look at the
parameters.

Look at the included C<Alzabo::Driver> subclasses for examples.  Feel
free to contact me for further help if you get stuck.  Please tell me
what database you're attempting to implement, what its DBD::* driver
is, and include the code you've written so far.

=head2 Virtual Methods

The following methods are not implemented in C<Alzabo::Driver> itself
and must be implemented in a subclass.

=head3 Parameters for connect(), create_database(), and drop_database()

=over 4

=item * user => $db_username

=item * password => $db_pw

=item * host => $hostname

=item * port => $port

=back

All of these default to undef.  See the appropriate DBD driver
documentation for more details.

After the driver is created, it will have access to its associated
schema object in C<< $self->{schema} >>.

=head2 connect

Some drivers may accept or require more arguments than specified
above.

Note that C<Alzabo::Driver> subclasses are not expected to cache
connections.  If you want to do this please use C<Apache::DBI> under
mod_perl or don't call C<connect()> more than once per process.

=head2 create_database

Attempts to create a new database for the schema attached to the
driver.  Some drivers may accept or require more arguments than
specified above.

=head2 drop_database

Attempts to drop the database for the schema attached to the driver.

=head2 schemas

Returns a list of schemas in the specified RDBMS.  This method may
accept some or all of the parameters which can be given to
C<connect()>.

=head2 supports_referential_integrity

Should return a boolean value indicating whether or not the RDBMS
supports referential integrity constraints.

=head2 next_sequence_number (C<Alzabo::Column> object)

This method is expected to return the value of the next sequence
number based on a column object.  For some databases (MySQL, for
example), the appropriate value is C<undef>.  This is accounted for in
the Alzabo code that calls this method.

=head2 begin_work

Notify Alzabo that you wish to start a transaction.

=head2 rollback

Rolls back the current transaction.

=head2 commit

Notify Alzabo that you wish to finish a transaction.  This is
basically the equivalent of calling commit.

=head2 get_last_id

Returns the last primary key id created via a sequenced column.

=head2 rdbms_version

Returns the version of the server to which the driver is connected.

=head2 driver_id

Returns the driver's name.  This should be something that can be
passed to C<< Alzabo::Driver->new() >> as a "name" parameter.

=head1 AUTHOR

Dave Rolsky, <dave@urth.org>

=cut