Re: SQL compatibility reminder: MySQL vs PostgreSQL

Andrew Dunstan wrote:

> But AIUI that won't be the same as the MySQL behaviour, as documented at
> <http://dev.mysql.com/doc/refman/5.5/en/group-by-hidden-columns.html>:
> 
>    When using this feature, all rows in each group should have the same
>    values for the columns that are ommitted from the |GROUP BY| part.
>    The server is free to return any value from the group, so the
>    results are indeterminate unless all values are the same.

That sounds a lot like the behavior of `DISTINCT ON (...)' and it'd
actually be really rather useful to have under some circumstances.

Whether it should be written as 'GROUP BY', though, isn't so clear.

--
Craig Ringer