sql - Oracle: '= ANY()' vs. 'IN ()'

Question

I just stumbled upon something in ORACLE SQL (not sure if it's in others), that I am curious about. I am asking here as a wiki, since it's hard to try to search symbols in google...

I just found that when checking a value against a set of values you can do

WHERE x = ANY (a, b, c)

As opposed to the usual

WHERE x IN (a, b, c)

So I'm curious, what is the reasoning for these two syntaxes? Is one standard and one some oddball Oracle syntax? Or are they both standard? And is there a preference of one over the other for performance reasons, or ?

Just curious what anyone can tell me about that '= ANY' syntax. CheerZ!

Answer 1

ANY (or its synonym SOME) is a syntax sugar for EXISTS with a simple correlation:

SELECT  *
FROM    mytable
WHERE   x <= ANY
        (
        SELECT  y
        FROM    othertable
        )

is the same as:

SELECT  *
FROM    mytable m
WHERE   EXISTS
        (
        SELECT  NULL
        FROM    othertable o
        WHERE   m.x <= o.y
        )

With the equality condition on a not-nullable field, it becomes similar to IN.

All major databases, including SQL Server, MySQL and PostgreSQL, support this keyword.