Re: Problems with distinct
| От | Owen Jacobson |
|---|---|
| Тема | Re: Problems with distinct |
| Дата | |
| Msg-id | 144D12D7DD4EC04F99241498BB4EEDCC20D48B@nelson.osl.com обсуждение исходный текст |
| Ответ на | Problems with distinct (Andreas Joseph Krogh <andreak@officenet.no>) |
| Список | pgsql-sql |
Andreas Joseph Krogh wrote: > Any idea why this works: > > SELECT distinct(g.groupname), g.id, g.p_id FROM onp_group g, > onp_group g2 > WHERE g.id IN(SELECT g2.id UNION SELECT group_id FROM > onp_group_children WHERE > child_id = g2.id) > AND g2.id IN(1,2,109,105, 112); > > And not this: > > SELECT g.id, g.p_id, distinct(g.groupname) FROM onp_group g, > onp_group g2 > WHERE g.id IN(SELECT g2.id UNION SELECT group_id FROM > onp_group_children WHERE > child_id = g2.id) > AND g2.id IN(1,2,109,105, 112); Distinct is an SQL keyword, not a function. The former is exactly equivalent to SELECT DISTINCT g.groupname, g.id, .... FROM .... except that the first field is inside a (trivial) expression that makes it look like a function call.
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