DBI::DBD::SqlEngine(3)

NAME
DBI::DBD::SqlEngine - Base class for DBI drivers without their own SQL engine

SYNOPSIS
    package DBD::myDriver;

    use base qw(DBI::DBD::SqlEngine);

    sub driver
    {
        ...
        my $drh = $proto->SUPER::driver($attr);
        ...
        return $drh->{class};
        }

    package DBD::myDriver::dr;

    @ISA = qw(DBI::DBD::SqlEngine::dr);

    sub data_sources { ... }
    ...

    package DBD::myDriver::db;

    @ISA = qw(DBI::DBD::SqlEngine::db);

    sub init_valid_attributes { ... }
    sub init_default_attributes { ... }
    sub set_versions { ... }
    sub validate_STORE_attr { my ($dbh, $attrib, $value) = @_; ... }
    sub validate_FETCH_attr { my ($dbh, $attrib) = @_; ... }
    sub get_myd_versions { ... }
    sub get_avail_tables { ... }

    package DBD::myDriver::st;

    @ISA = qw(DBI::DBD::SqlEngine::st);

    sub FETCH { ... }
    sub STORE { ... }

    package DBD::myDriver::Statement;

    @ISA = qw(DBI::DBD::SqlEngine::Statement);

    sub open_table { ... }

    package DBD::myDriver::Table;

    @ISA = qw(DBI::DBD::SqlEngine::Table);

    sub new { ... }

DESCRIPTION
DBI::DBD::SqlEngine abstracts the usage of SQL engines from the DBD. DBD authors can concentrate on the data retrieval they want to provide.

It is strongly recommended that you read DBD::File::Developers and DBD::File::Roadmap, because many of the DBD::File API is provided by DBI::DBD::SqlEngine.

Currently the API of DBI::DBD::SqlEngine is experimental and will likely change in the near future to provide the table meta data basics like DBD::File.

  Metadata
The following attributes are handled by DBI itself and not by DBI::DBD::SqlEngine, thus they all work as expected:

    Active
    ActiveKids
    CachedKids
    CompatMode             (Not used)
    InactiveDestroy
    AutoInactiveDestroy
    Kids
    PrintError
    RaiseError
    Warn                   (Not used)

The following DBI attributes are handled by DBI::DBD::SqlEngine:

AutoCommit

Always on.

ChopBlanks

Works.

NUM_OF_FIELDS

Valid after "$sth->execute".

NUM_OF_PARAMS

Valid after "$sth->prepare".

NAME

Valid after "$sth->execute"; probably undef for Non-Select statements.

NULLABLE

Not really working, always returns an array ref of ones, as DBD::CSV does not verify input data. Valid after "$sth->execute"; undef for non-select statements.

The following DBI attributes and methods are not supported:

bind_param_inout
CursorName
LongReadLen
LongTruncOk

DBI::DBD::SqlEngine specific attributes

In addition to the DBI attributes, you can use the following dbh attributes:

sql_engine_version

Contains the module version of this driver (readonly)

sql_nano_version

Contains the module version of DBI::SQL::Nano (readonly)

sql_statement_version

Contains the module version of SQL::Statement, if available (readonly)

sql_handler

Contains the SQL Statement engine, either DBI::SQL::Nano or SQL::Statement (readonly).

sql_parser_object

Contains an instantiated instance of SQL::Parser (readonly). This is filled when used first time (only when used with SQL::Statement).

sql_sponge_driver

Contains an internally used DBD::Sponge handle (readonly).

sql_valid_attrs

Contains the list of valid attributes for each DBI::DBD::SqlEngine based driver (readonly).

sql_readonly_attrs

Contains the list of those attributes which are readonly (readonly).

sql_identifier_case

Contains how DBI::DBD::SqlEngine deals with non-quoted SQL identifiers:

  * SQL_IC_UPPER (1) means all identifiers are internally converted
    into upper-cased pendants
  * SQL_IC_LOWER (2) means all identifiers are internally converted
    into lower-cased pendants
  * SQL_IC_MIXED (4) means all identifiers are taken as they are

These conversions happen if (and only if) no existing identifier matches. Once existing identifier is used as known.

The SQL statement execution classes doesn't have to care, so don't expect "sql_identifier_case" affects column names in statements like

  SELECT * FROM foo

sql_quoted_identifier_case

Contains how DBI::DBD::SqlEngine deals with quoted SQL identifiers (readonly). It's fixated to SQL_IC_SENSITIVE (3), which is interpreted as SQL_IC_MIXED.

sql_flags

Contains additional flags to instantiate an SQL::Parser. Because an SQL::Parser is instantiated only once, it's recommended to set this flag before any statement is executed.

sql_dialect

Controls the dialect understood by SQL::Parser. Possible values (delivery state of SQL::Statement):

  * ANSI
  * CSV
  * AnyData

Defaults to "CSV". Because an SQL::Parser is instantiated only once and SQL::Parser doesn't allow to modify the dialect once instantiated, it's strongly recommended to set this flag before any statement is executed (best place is connect attribute hash).

SUPPORT
You can find documentation for this module with the perldoc command.

    perldoc DBI::DBD::SqlEngine

You can also look for information at:

•   RT: CPAN's request tracker

    <http://rt.cpan.org/NoAuth/Bugs.html?Dist=DBI> http://rt.cpan.org/NoAuth/Bugs.html?Dist=SQL-Statement <http://rt.cpan.org/NoAuth/Bugs.html?Dist=SQL-Statement>

•   AnnoCPAN: Annotated CPAN documentation

    <http://annocpan.org/dist/DBI> http://annocpan.org/dist/SQL-Statement <http://annocpan.org/dist/SQL-Statement>

•   CPAN Ratings

    <http://cpanratings.perl.org/d/DBI>

•   Search CPAN

    <http://search.cpan.org/dist/DBI/>

  Where can I go for more help?
For questions about installation or usage, please ask on the dbi-dev@perl.org mailing list.

If you have a bug report, patch or suggestion, please open a new report ticket on CPAN, if there is not already one for the issue you want to report. Of course, you can mail any of the module maintainers, but it is less likely to be missed if it is reported on RT.

Report tickets should contain a detailed description of the bug or enhancement request you want to report and at least an easy way to verify/reproduce the issue and any supplied fix. Patches are always welcome, too.

ACKNOWLEDGEMENTS
Thanks to Tim Bunce, Martin Evans and H.Merijn Brand for their continued support while developing DBD::File, DBD::DBM and DBD::AnyData. Their support, hints and feedback helped to design and implement this module.

AUTHOR
This module is currently maintained by

H.Merijn Brand < h.m.brand at xs4all.nl > and Jens Rehsack < rehsack at googlemail.com >

The original authors are Jochen Wiedmann and Jeff Zucker.

COPYRIGHT AND LICENSE
 Copyright (C) 2009-2010 by H.Merijn Brand & Jens Rehsack
 Copyright (C) 2004-2009 by Jeff Zucker
 Copyright (C) 1998-2004 by Jochen Wiedmann

All rights reserved.

You may freely distribute and/or modify this module under the terms of either the GNU General Public License (GPL) or the Artistic License, as specified in the Perl README file.

SEE ALSO
DBI, DBD::File, DBD::AnyData and DBD::Sys.