SELECT query

I have three table called table1, table2, table3 all having fields like: table1 contain id and username and id referencing table4 table2 contains id and parallel_username and id referencing table4 table3 contains id and other_username and id referencing table4 table4 is the main table containing id as primary key I want to develop a search engine which shows unique record after searching all the three table but shouldn't contain multiple answers for same SEARCH for username Pls help me, -Regards Sharmad -- The secret of the universe is @*&í!'ñ^#+ NO CARRIER __ _ _ _ _ |_|_||_||_||\/||_|| \ _|| || || \| || ||_/