Record Insert only if field entry doesn't already exist
I am trying to figure out how to insert a new record into a table, but only if one of the fields in that table doesn't contain the same informtion already. The intent here is to eliminate duplicate data entries. So I need to validate or check to make sure that table1.field1 isn't the same as the data being entered into the new record in table1.field1 from the insert new record form page. I guess I could make the field unique in MySQL, but I'd like to have a formatted dialog error response instead.
Example: Email Address List
Insert new email address into new record into email table, only if the the new email address doesn't already exist in the email table.
I own both DataAssist Pro and the Validation Tool Kit.
Thanks in advance for your comments.