--On Thursday, September 25, 2003 20:09:35 +0100 Richard Huxton <[EMAIL PROTECTED]> wrote:
On Thursday 25 September 2003 19:51, Larry Rosenman wrote:I wasn't sure I could do that. Thanks!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
LER
-- Larry Rosenman http://www.lerctr.org/~ler Phone: +1 972-414-9812 E-Mail: [EMAIL PROTECTED] US Mail: 1905 Steamboat Springs Drive, Garland, TX 75044-6749
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