Hey, I've just find out what's happening. The problem is the "serial" datatype creates a sequence in the background (project_id_seq). If the sequence current numeber is 1, and I manually insert a new entry whit ID=2, the sequence doesn't "know" it. So when I try the INSERT statement, the next value in sequence is 2, and I get the error. The thing is, I'm migrating my system from mysql to postgresql, and that's why I was inserting directely the numbers (importing the .sql file), without respecting the backgroud sequence. Thanks a lot for those who answered me. Regards, Verônica
