Hi, I´m a brazilian programmer! I have a question about Postgres UNIQUE KEY. Look: (Step 1) CREATE TABLE test ( id integer not null primary key, id_uni integer not null, cod integer, name varchar(40), constraint test_uk unique(id_uni, cod) ) (Step 2) insert into test (id, id_uni, cod, name) values (1, 1, null, 'A') (Step 3) insert into test (id, id_uni, cod, name) values (2, 1, null, 'B') =========> [Have the same UNIQUE KEY] Why postgresql don´t break insertion in this case???? Thanks Diego Ziquinatti Brazil ---------------------------(end of broadcast)--------------------------- TIP 4: Have you searched our list archives? http://archives.postgresql.org