Hi,

Generally speaking which is the quicker option

select x
from table a, table b
where a.x = b.x
or
select x
from table a
where a.x IN
(select b.x
from table b)

Also if there are 2 join conditions such as a.x = b.x AND a.c = b.c

Thanx.

The first way is quicker, since it doesn't build a temporary table in memory for the set.

BUT - most database engines will perform even faster if you use the JOIN syntax.

Select a.x
FROM tablea a
JOIN tableb b
WHERE a.x=b.x

And make sure that a.x and b.x are primary keys !!!

-Chris
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