Garrett,

> LEFT JOIN b ON a.key = b.key*AND b.field = 'Value'*

is it the conditions/filters (AND b.field = 'Value') that you are asking

about, not the difference between WHERE and JOIN?

If so, then this might help:

https://stackoverflow.com/questions/10517225/filtering-joins-where-vs-on

or this:

https://stackoverflow.com/questions/10297231/where-clause-vs-on-when-using-join

Frank.

Frank Cazabon

On 02/04/2019 06:05 PM, Garrett Fitzgerald wrote:

> Hey, all. I had a general SQL question. Often, I find myself needing to use

> the syntax:

>

> FROM a

> LEFT JOIN b ON a.key = b.key AND b.field = 'Value'

>

> because if I filter b.field in the WHERE clause, I've effectively made the

> LEFT JOIN an inner one.

>

> That makes me wonder, at what point do we stop moving conditions to the

> JOIN clause? Obviously, some can't move for syntactical reasons, such as

> subqueries. But short of that, when does it make sense to limit a non-outer

> join in the join criteria? Never?

>

>

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