On Tue, Jan 12, 2010 at 7:45 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> "Vee" <sefer@hotmail.com> writes:
>> -- The problem query
>> select data, regexp_matches(data, '(h..l)')
>> from test;
>
>>> hello =A0 =A0 =A0 =A0{hell}
>
>> Since I have no "where" clause, I would expect to see all the rows in the
>> result of the second case, with possibly a NULL value for the non-matched
>> rows.
>
> No. =A0regexp_matches() returns setof something, meaning a row per match.
> When you have no match, you get no rows. =A0And that in turn means that
> the calling select produces no rows --- just as it could also produce
> more than one row from a given table row.
>
> I think the behavior you are after is probably more like that of
> substring().
Or maybe the ~ operator.
...Robert
