Duplicate Rows Blues

Hello,
I would like to prevent Contacts being inserted into the database when inserted Contact:

firstname + ', ' + lastname + ', ' + workphone

is identical with existing Contacts:

firstname + ', ' + lastname + ', ' + workphone

Can this be done with an Insert Trigger and if so, how? Thank you in advance,
LarsYou could add an alternate key to the entity on those attributes. In your physical implementation, add a "UNIQUE" constraint and a unique index on those columns. It could be done with a trigger, but it will probably not preform as well.|||I'll second that recommendation. A UNIQUE constraint should be more efficient (and simpler) than any trigger you could write.

-PatPsql