SQL left join vs multiple tables on FROM line?

Question

Most SQL dialects accept both the following queries:

SELECT a.foo, b.foo
FROM a, b
WHERE a.x = b.x

SELECT a.foo, b.foo
FROM a
LEFT JOIN b ON a.x = b.x
         


        

Answer 1

To the database, they end up being the same. For you, though, you'll have to use that second syntax in some situations. For the sake of editing queries that end up having to use it (finding out you needed a left join where you had a straight join), and for consistency, I'd pattern only on the 2nd method. It'll make reading queries easier.