| From: | "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com> |
|---|---|
| To: | jonathan vanasco <postgres(at)2xlp(dot)com> |
| Cc: | pgsql-general general <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: why isn't this subquery wrong? |
| Date: | 2017-04-20 23:16:56 |
| Message-ID: | CAKFQuwY4o3G323LtKe_NWjBA+TEE99J01=w17vcdEcB=yZwOXA@mail.gmail.com |
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| Lists: | pgsql-general |
On Thu, Apr 20, 2017 at 3:17 PM, jonathan vanasco <postgres(at)2xlp(dot)com> wrote:
>
> SELECT foo_id
> FROM example_a__data
> WHERE foo_id IN (SELECT bar_id FROM example_a__rollup)
> ;
>
>
>
Or write it the idiomatic way (i.e., as a proper semi-join):
SELECT foo_id
FROM example_a__data
WHERE EXISTS (SELECT 1
FROM example_a__rollup
WHERE example_a__rollup.bar_id =
example_a__data.foo_id)
IME its harder to forget the table prefix when using this form.
David J.
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