On Thu, Dec 19, 2002 at 09:15:36AM -0800, Josh Berkus wrote:
> > -select * from some_table t
> > left join filter f using (id)
> > where f.id is [not] null;
>
> This will not get you the same result as the above. It will get you
> all rows from t+f where a record is present in f and has (or does not
> have) a NULL value for f.id. While this type of query works in MS
> Access, it will not work in SQL92/99-commpliant databases.
filter_table does not contain null fields. It has only two states: it
has row
or it hasn't row coresponding to row in some_table.
And now, which one is better?
Tomasz Myrta
