The Merge Table
Options section is used to
configure MERGE tables in MyISAM. To create a MERGE table,
select MERGE as your storage engine in the
Table Options
Tab and then specify the tables you wish to MERGE in the
Union Tables dialog.
You can also specify the action the server should take when users attempt to perform INSERT statements on the merge table. See http://dev.mysql.com/doc/mysql/en/MERGE.html for more information on MERGE tables.