DBD::File

DBD::File(3)	     User Contributed Perl Documentation	 DBD::File(3)



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::State-
       ment 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 cur-
	   rent directory ("."). However, it is overwritable in the statement
	   handles.

       f_ext
	   This attribute is used for setting the file extension where (CSV)
	   files are opened. There are several possibilities.

	       DBI:CSV:f_dir=data;f_ext=.csv

	   In this case, DBD::File will open only "table.csv" if both "ta-
	   ble.csv" and "table" exist in the datadir. The table will still be
	   named "table". If your datadir has files with extensions, and you
	   do not pass this attribute, your table is named "table.csv", which
	   is probably not what you wanted. The extension is always
	   case-insensitive. The table names are not.

	       DBI:CSV:f_dir=data;f_ext=.csv/r

	   In this case the extension is required, and all filenames that do
	   not match are ignored.

       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 func-
	       tion is not available on all platforms. Using flock () is dis-
	       abled on MacOS and Windows 95: There’s no locking at all (per-
	       haps not so important on MacOS and Windows 95, as there’s a
	       single user anyways).

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 author is Jochen Wiedmann.

COPYRIGHT AND LICENSE
       Copyright (C) 2009 by H.Merijn Brand & Jens Rehsack 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, Text::CSV, Text::CSV_XS, SQL::Statement



perl v5.8.8			  2009-05-02			 DBD::File(3)