DBD::File - Base class for writing DBI drivers
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).
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.
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:
Always on
Works
Valid after $sth-execute>
$sth-
Valid after $sth-prepare>
Valid after $sth-execute>; undef for Non-Select statements.
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:
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.
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 table.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.
table.csv
table
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.
This will set the schema name. Default is the owner of the folder in which the table file resides. undef is allowed.
undef
my $dbh = DBI->connect ("dbi:CSV:", "", "", { f_schema => undef, f_dir => "data", f_ext => ".csv/r", }) or die $DBI::errstr;
The effect is that when you get table names from DBI, you can force all tables into the same (or no) schema:
my @tables $dbh->tables (); # no f_schema "merijn".foo "merijn".bar # f_schema => "dbi" "dbi".foo "dbi".bar # f_schema => undef foo bar
The data_sources method returns a list of subdirectories of the current directory in the form "DBI:CSV:f_dir=$dirname".
data_sources
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" );
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.
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).
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 (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.
DBI, Text::CSV, Text::CSV_XS, SQL::Statement
To install DBI, copy and paste the appropriate command in to your terminal.
cpanm
cpanm DBI
CPAN shell
perl -MCPAN -e shell install DBI
For more information on module installation, please visit the detailed CPAN module installation guide.