On Apr 20, 2006, at 4:51 AM, Robert Zeigler wrote:
> Hm. That's interesting... I haven't looked at the queries generated
> for
> the new stuff... if I was writing raw sql, I probably would have
> done a
> left outer join (but maybe not enough db vendors support it???) and
> used
> an "ON" clause for the join, rather than a where clause... I always
> thought that "Where" is for winnowing results, and "on" is for joining
> tables...? I'll confess to being curious as to the rational for using
> "where" for a joint prefetch rather than "on".
ON is supposedly a standard SQL syntax for both INNER and OUTER
joins, however historically most databases did the joins as a part of
WHERE clause. For instance an OUTER join on Oracle could be done like
this:
select t1.* from painting t1, artist t2
where t1.artist_id = t2.artist_id (+)
We'll be considering the "standard" syntax of with ON when we start
work on OUTER joins support in relationships.
Andrus
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