On Jul 1, 2006, at 6:55 , Richard Broersma Jr wrote:
CHECK ( 1 = ALL ( SELECT COUNT(STATUS)
FROM BADGES
WHERE STATUS = 'A'
GROUP BY EMPNO))
From the PostgreSQL docs (http://www.postgresql.org/docs/8.1/
interactive/sql-createtable.html)
Currently, CHECK expressions cannot contain subqueries nor refer to
variables other than columns of the current row.
This is why the the above won't work. You can probably do something
similar by creating UNIQUE index with a WHERE clause. For example (if
I'm understanding the intent),
CREATE UNIQUE INDEX one_a_badge_per_employee_idx
ON badges (empno)
WHERE status = 'A';
Here are links to more documentation on indexes:
http://www.postgresql.org/docs/8.1/interactive/sql-createindex.html
http://www.postgresql.org/docs/8.1/interactive/indexes-partial.html
Hope this helps.
Michael Glaesemann
grzm seespotcode net
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