DBD::File - Base class for writing DBI drivers

- NAME
- SYNOPSIS
- DESCRIPTION

- Metadata
- Driver private methods

- KNOWN BUGS
- AUTHOR AND COPYRIGHT
- SEE ALSO

# NAME

DBD::File - Base class for writing DBI drivers

# SYNOPSIS

     This module is a base class for writing other DBDs.
     It is not intended to function as a DBD itself.
     If you want to access flatfiles, use DBD::AnyData, or DBD::CSV,
     (both of which are subclasses of DBD::File).

# DESCRIPTION

The DBD::File module is not a true DBI driver, but an abstract base class for deriving concrete DBI drivers from it. The implication is, that these drivers work with plain files, for example CSV files or INI files. The module is based on the SQL::Statement module, a simple SQL engine.

See DBI for details on DBI, the SQL::Statement manpage for details on SQL::Statement and the DBD::CSV manpage or the DBD::IniFile manpage for example drivers.

## Metadata

The following attributes are handled by DBI itself and not by DBD::File, thus they all work like expected:

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

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

AutoCommit
  Always on

ChopBlanks
  Works

NUM_OF_FIELDS
  Valid after `$sth-`execute>

NUM_OF_PARAMS
  Valid after `$sth-`prepare>

NAME
  Valid after `$sth-`execute>; undef for Non-Select statements.

NULLABLE
  Not really working, always returns an array ref of one's, as DBD::CSV doesn't verify input data. Valid after `$sth-`execute>; undef for Non-Select statements.

These attributes and methods are not supported:

        bind_param_inout
        CursorName
        LongReadLen
        LongTruncOk

Additional to the DBI attributes, you can use the following dbh attribute:

f_dir
  This attribute is used for setting the directory where CSV files are opened. Usually you set it in the dbh, it defaults to the current directory (``.''). However, it is overwritable in the statement handles.

## Driver private methods

data_sources
  The `data_sources` method returns a list of subdirectories of the current directory in the form ``DBI:CSV:f_dir=$dirname''.

  If you want to read the subdirectories of another directory, use

          my($drh) = DBI->install_driver("CSV");
          my(@list) = $drh->data_sources('f_dir' => '/usr/local/csv_data' );

list_tables
  This method returns a list of file names inside $dbh->{'f_dir'}. Example:

          my($dbh) = DBI->connect("DBI:CSV:f_dir=/usr/local/csv_data");
          my(@list) = $dbh->func('list_tables');

  Note that the list includes all files contained in the directory, even those that have non-valid table names, from the view of SQL.

# KNOWN BUGS

The module is using `flock()` internally. However, this function is not available on all platforms. Using `flock()` is disabled on MacOS and Windows 95: There's no locking at all (perhaps not so important on MacOS and Windows 95, as there's a single user anyways).

# AUTHOR AND COPYRIGHT

This module is currently maintained by

Jeff Zucker < jzucker @ cpan.org >

The original author is Jochen Wiedmann.

Copyright (C) 2004 by Jeff Zucker Copyright (C) 1998 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, the Text::CSV_XS manpage, the SQL::Statement manpage

DBD::File - Base class for writing DBI drivers