The way to do this is to create a copy of the table using In this example I will assume I have a table called apple in database plum, and the column you want to make unique is called fruit select * into tempdb..apple from plum..apple next create an identity column on this new table: alter table tempdb..apple add pip numeric(5,0) identity The following query will now eliminate the duplicate entries of fruit; delete from tempdb..apple where pip in (select a.pip from tempdb..apple a, tempdb..apple b where a.fruit = b.fruit and a.pip > b.pip) You will now have the table unique on the column fruit and you can put the data back into the original table (minus the identity column created with the following: First delete or truncate the original plum..apple then Select fruit,… , <columns in plum..apple> Into plum..apple From tempdb..apple