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    <p>Whilst this doesn't help you on InnoDB, it's worth pointing out that MyISAM natively supports this functionality. As documented under <a href="http://dev.mysql.com/doc/en/example-auto-increment.html" rel="nofollow">Using <code>AUTO_INCREMENT</code></a>:</p> <blockquote> <h3>MyISAM Notes</h3> <p>For <code>MyISAM</code> tables, you can specify <code>AUTO_INCREMENT</code> on a secondary column in a multiple-column index. In this case, the generated value for the <code>AUTO_INCREMENT</code> column is calculated as <a href="http://dev.mysql.com/doc/en/group-by-functions.html#function_max" rel="nofollow"><code>MAX(<em>auto_increment_column</em>) + 1 WHERE prefix=<em>given-prefix</em></code></a>. This is useful when you want to put data into ordered groups.</p> <pre> CREATE TABLE animals ( grp ENUM('fish','mammal','bird') NOT NULL, id MEDIUMINT NOT NULL AUTO_INCREMENT, name CHAR(30) NOT NULL, PRIMARY KEY (grp,id) ) ENGINE=MyISAM; INSERT INTO animals (grp,name) VALUES ('mammal','dog'),('mammal','cat'), ('bird','penguin'),('fish','lax'),('mammal','whale'), ('bird','ostrich'); SELECT * FROM animals ORDER BY grp,id; </pre> <p>Which returns:</p> <pre> +--------+----+---------+ | grp | id | name | +--------+----+---------+ | fish | 1 | lax | | mammal | 1 | dog | | mammal | 2 | cat | | mammal | 3 | whale | | bird | 1 | penguin | | bird | 2 | ostrich | +--------+----+---------+ </pre> <p>In this case (when the <code>AUTO_INCREMENT</code> column is part of a multiple-column index), <code>AUTO_INCREMENT</code> values are reused if you delete the row with the biggest <code>AUTO_INCREMENT</code> value in any group. This happens even for <code>MyISAM</code> tables, for which <code>AUTO_INCREMENT</code> values normally are not reused.</p> </blockquote>
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    1. COLet me try that out.
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    2. COAwesome. That works.Thanks a lot
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