Re: Using regexp_matches in the WHERE clause

> > So I tried:
> >
> > SELECT *
> > FROM some_table
> > WHERE regexp_matches(somecol, 'foobar') is not null;
> >
> > However that resulted in: ERROR: argument of WHERE must not return a set
> >
> > Hmm, even though an array is not a set I can partly see what the problem is
> > (although given the really cool array implementation in PostgreSQL I was a bit surprised).
> >
> >
> > So I though, if I convert this to an integer, it should work:
> >
> > SELECT *
> > FROM some_table
> > WHERE array_length(regexp_matches(somecol, 'foobar'), 1) > 0
> >
> > but that still results in the same error.
> >
> > But array_length() clearly returns an integer, so why does it still throw this error?
> >
> >
> > I'm using 9.2.1
> >

> Sounds to me like this:
>
> http://joecelkothesqlapprentice.blogspot.nl/2007/12/using-where-clause-parameter.html
>

Thanks, but my question is not related to the underlying problem.

My question is: why I cannot use regexp_matches() in the WHERE clause, even when the result is clearly an integer value?

Regards
Thomas