Re: [GENERAL] Turning a subselect into an array

Thanks again for the help. I did manage to find that after a bunch of
searching in the mailing list. There should really be a portion of the
docs dedicated to array handling.

On Fri, Oct 29, 2004 at 10:40:57PM -0600, Michael Fuhr wrote:
> On Fri, Oct 29, 2004 at 05:13:02PM -0500, Jim C. Nasby wrote:
> > Ok, next stupid question that I can't find in the docs... How would I
> > join a table to an array? IE: if I have an array of primary keys for
> > some table and I want to get the name field from that table and turn it
> > back into an array, how would I do that?
>
> See the "Subquery Expressions" and "Row and Array Comparisons"
> sections in the PostgreSQL documentation:
>
> http://www.postgresql.org/docs/7.4/static/functions-subquery.html
> http://www.postgresql.org/docs/7.4/static/functions-comparisons.html
>
> If I understand you correctly, this should work:
>
> SELECT ARRAY(SELECT name FROM foo WHERE id = ANY(ARRAY[1,2,3]));
>
> A test I just ran showed "id = ANY(ARRAY[1,2,3])" doing a sequential
> scan whereas "id IN (1,2,3)" did an index scan, so you might want to
> use the latter if possible.
>
> --
> Michael Fuhr
> http://www.fuhr.org/~mfuhr/
>
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--
Jim C. Nasby, Database Consultant decibel(at)decibel(dot)org
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