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

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.

Answer 2

This is a standard. The SQL 1992 standard states

8.4 <in predicate>

[...]

<in predicate> ::=
    <row value constructor>
      [ NOT ] IN <in predicate value>

[...]

2) Let RVC be the <row value constructor> and let IPV be the <in predicate value>.

[...]

4) The expression

  RVC IN IPV

is equivalent to

  RVC = ANY IPV  

So in fact, the <in predicate> behaviour definition is based on the 8.7 <quantified comparison predicate>. In Other words, Oracle correctly implements the SQL standard here

Answer 3

I believe that what you are looking for is this:

http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96533/opt_ops.htm#1005298 (Link found on Eddie Awad's Blog) To sum it up here:

last_name IN ('SMITH', 'KING', 'JONES')

is transformed into

last_name = 'SMITH' OR last_name = 'KING' OR last_name = 'JONES'

while

salary > ANY (:first_sal, :second_sal)

is transformed into

salary > :first_sal OR salary > :second_sal

The optimizer transforms a condition that uses the ANY or SOME operator followed by a subquery into a condition containing the EXISTS operator and a correlated subquery