> Hi all, > I guess this is an already asked question, but I didn't found an answer, so > apologize me. Imagine I've got two tables: > skill(id,description) // primary key => id > family(id,description) // primary key => id > and I want to associate skills to families: > ass_sf(id_skill,id_family) // appropriate foreign keys > > Tables are already created and the database is running. Now I'd like to > implement a delete cascade, thus when I delete a skill also its association > with the family must be deleted. I gues I should have declared the skill > table as follows: > CREATE TABLE skill > ( > id varchar(20) on delete cascade, > description varchar(50), > primary key(id) > ); > > right? The problem is: how can I alter the table to add the column constraint > now, without redeclaring the table? > Thanks very much for helping me.
This link has one line that is very similar to what you want to do. You will probably have to start a transaction, drop the foriegn key contraint and then add a new foriegn key contraint with the on drop cascade . http://archives.postgresql.org/pgsql-general/2006-10/msg00467.php Regards, Richard Broersma Jr. ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match
