On Thursday 25 September 2003 19:51, Larry Rosenman wrote: > I have the following rows (in addition to others): > > acct_num text, > master_acct_num text, > > > These are in the same table. > > What I want to enforce is that if the master_acct_num field is NOT NULL (it > can be NULL, and > that's fine), that the value appears in some row as acct_num. acct_num has > a unique index on it, so that's fine. > > I'm not sure how to do this....
ALTER TABLE my_table ADD CONSTRAINT my_self_fk FOREIGN KEY (master_acct_num) REFERENCES my_table (acct_num); It's really just a foreign-key to yourself -- Richard Huxton Archonet Ltd ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend
