This is Tie::DBI and Tie::RDBM, two modules that allow you to tie
associative arrays to relational databases using the DBI library.  The
hash is tied to a table in a local or networked database.  Reading
from the hash retrieves values from the datavbase.  Storing into the
hash updates the database (if you have sufficient privileges).

Tie::DBI implements a fully general binding between the hash and the
table, allowing you to access fields in this manner:

   $h{strawberries}->{quantity} = 228;

Tie::RDBM implements a more limited binding which gives you access to
only one column of the table.  However it is faster, can create and
destroy tables on the fly, and provides an interface whereby you can
store and retrieve complex Perl objects from the database table.

In addition to this package, you will need the DBI database interface
module, plus the DBD driver for the database of your choice.  To be
able to store and retrieve non-scalar values via the Tie::RDBM
interface you will also need Storable.pm These are all available at a
CPAN near you:

	http://www.perl.com/CPAN/

To install:

	1. perl Makefile.PL
	2. make
	3. make test [optional]
	4. make install

To read the documentation:

	perldoc Tie::DBI
        perldoc Tie::RDBM

"make test" requires you to have a database named "test" up and
running on the local machine.  The test script will search for an
installed DBD driver to use.  You can override its choice by
specifying DRIVER=<driver name> on the command line.  For example:
	
	make test DRIVER=mysql

Databases differ in their capabilities, and some can't support binary
data types.  On those databases, Tie::RDBM test #14 will fail.  The
same test will fail if you do not have Storable.pm installed on your
system.  This is nothing to worry about.

The home page for this module is
http://www.genome.wi.mit.edu/~lstein/Tie-DBI/.  See here for updates.

For more information, see the perldoc documentation.

Lincoln Stein
January 19, 1998