NAME
    "DBIx::Table2Hash" - Read a database table into a hash

Version
    This document refers to version 1.00 of "DBIx::Table2Hash", released
    8-Jan-2003.

Synopsis
            #!/usr/bin/perl

            my($hash_ref) = DBIx::Table2Hash -> new
            (
                    dbh          => $dbh,
                    table_name   => $table_name,
                    key_column   => 'name',
                    value_column => 'id'
            ) -> select();

Description
    "DBIx::Table2Hash" is a pure Perl module.

    This module reads a database table and stores keys and values in a hash.
    The resultant hash is not nested in any way.

    The aim is to create a hash which is a simple look-up table. To this
    end, the module allows the key_column to point to an SQL expression.

Constructor and initialization
    new(...) returns a "DBIx::Table2Hash" object.

    This is the class's contructor.

    Parameters:

    *   dbh

        A database handle.

    *   table_name

        The name of the table to select from.

    *   key_column

        The name of the column, or SQL expression, to use for hash keys.

        Say you have 2 columns, called col_a and col_b. Then you can
        concatenate them with:

        key_column => 'concat(col_a, col_b)'

        or, even fancier,

        key_column => "concat(col_a, '-', col_b)"

    *   value_column

        The name of the column to use for hash values.

    *   where

        The optional where clause, including the word 'where', to add to the
        select.

Method: new(...)
    Returns a object of type "DBIx::Table2Hash".

    See above, in the section called 'Constructor and initialization'.

Method: select()
    Returns a hash ref.

    Calling select() actually executes the SQL select statement, and builds
    the hash.

Required Modules
    DBI, so you can provide a database handle.

Changes
    See Changes.txt.

FAQ
    Q: What is the point of this module?

    A: To be able to restore a hash from a database rather than from a file.

    Q: Can your other module "DBIx::Hash2Table" be used to save the hash
    back to the database?

    A: Sure.

    Q: Are there any other modules with similar capabilities?

    A: Yes:

    *   "DBIx::Lookup::Field"

        Quite similar.

    *   "DBIx::TableHash"

        This module takes a very long set of parameters, but unfortunately
        does not take a database handle.

        It does mean the module, being extremely complex, can read in more
        than one column as the value of a hash key, and it has caching
        abilities too.

        It works by tieing a hash to an MySQL table, and hence supports
        writing to the table. It uses MySQL-specific code, for example, when
        it locks tables.

        Unfortunately, it does not use data binding, so it cannot handle
        data which contains single quotes!

        Further, it uses /^\w+$/ to 'validate' column names, so it cannot
        accept an SQL expression instead of a column name.

        Lastly, it also uses /^\w+$/ to 'validate' table names, so it cannot
        accept table names and views containing spaces and other 'funny'
        characters, eg '&' (both of which I have to deal with under MS
        Access).

    *   "DBIx::Tree"

        This module is more like the inverse of "DBIx::Hash2Table", in that
        it assumes you are building a nested hash.

        As it reads the database table it calls a call-back sub, which you
        use to process the rows of the table.

Author
    "DBIx::Table2Hash" was written by Ron Savage *<ron@savage.net.au>* in
    2003.

    Home page: http://savage.net.au/index.html

Copyright
    Australian copyright (c) 2003, Ron Savage. All rights reserved.

            All Programs of mine are 'OSI Certified Open Source Software';
            you can redistribute them and/or modify them under the terms of
            The Artistic License, a copy of which is available at:
            http://www.opensource.org/licenses/index.html