Hi I have two tables. There are users informations from two sites: p_users p_users2 There are 3726 users in first and 13717 in second. Some users in p_users2 are in p_users. I want merge this two tables to the one big table - but rows with same usernames can't be doubled. How can I do this? I tried something like this: DELETE FROM p_users2 WHERE user_id IN ( select p.user_id from p_users p join p_users2 p2 on p.username=p2.username ) After that I should receive a table with unique usernames, which I want to export and import to the first one. But when I execute my query I got error: SQL Error (1093): You can't specify target table 'p_users2' for update in FROM clause. (MYSQL)