[SQL] Add Constraint

[Sivagami .]

Hi all,   I am a newbie to Postgresql, but I am familiar with SQL. I am trying to add a constraint to my table using the ALTER TABLE command. The command goes like this :   ALTER TABLE USER_SIGNUP ADD CONSTRAINT P_USER_SIGNUP_USER_ID PRIMARY KEY(user_id);   But it is returning the error ERROR:  ALTER TABLE / ADD CONSTRAINT is not implemented   Can anyone guide me in the right direction???   Thanks. Shiva