The former syntax is an implicit inner join. It is more common in industry where programmers are building queries on a daily basis because it is easier for programmers to read, but it is identical in function to the explicit join syntax you are asking about.

The explicit syntax allows easier refactoring to outer joins, and may give the optimizer better direction in binding complex queries, but once the binding (prepare) is done the performance should be the same.

----- Original Message -----
From: Steffen Heil
To: firebird-support@yahoogroups.com
Sent: Wednesday, March 10, 2004 1:47 AM
Subject: [firebird-support] JOINs vs WHERE


Hi

I have a question. It is very SQL-basic.

What are JOINs good for?

From what I read, I can do

select a.avalue, b.bvalue
from atable a, btable b
where a.id = b.id

as

select a.avalue, b.bvalue
from atable a join btable b
on a.id = b.id

Is there a difference? Until now, I only used the former approch, as it
seems more "natural" to me.

I also read about differences between diffent kinds of JOINS [left, inner,
outer, ..?]
Is there a good place to read about the differences?

Thanks,
Steffen


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