> >>>> 2011/08/02 12:11 +0530, Adarsh Sharma >>>>
>
> select p.* from table A p, B q where p.id=q.id
>
> or
>
> select p.* from table B q , A p where q.id=p.id
> <<<<<<<<
> Why do people constantly change table names for queries, although, as here,
> it gain them nothing? It often makes for less clarity (for which table is
> this an alias???).
Depens on your table names. I rather like being able to give a short
description rather then long table names if someone decided that as a
tablename. I doubt your example with already short tablenames is one from real
life, but if you saw someone doing it would indeed be a waste of time. But the
main thing is it helps to distinguish tables in joins having the same table
more then once (and of course results from subqueries etc.):
SELECT first.*
FROM tablename first
LEFT JOIN tablename second
ON first.some_id = second.some_id
AND first.id != second.id
WHERE second.id IS NULL
--
Rik Wasmus
