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, SQL::Statement for details on SQL::Statement and DBD::CSV or DBD::IniFile 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.

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.