Hi,
I've managed to copy and change the ajax-validate-plugin such that it will check two form-fields against two corresponding database-fields in one table.
A simple sql count(*) returns 0 or more rows. If > 0 => error-label should be shown and save should be prevented...
SQL-execution works fine and field-logic works also (formfield1 = dbfield1 AND formfield2 = dbfield2).However the content-item always gets saved (created) and no error is thrown...
I can provide current plugin if desired.
This plugin is handy in checking existence before storing M=>N relation-types.
Thanks in advance
Mark