IN Clause with NULL or IS NULL

Question

Postgres is the database

Can I use a NULL value for a IN clause? example:

SELECT *
FROM tbl_name
WHERE id_field IN (\'value1\', \'value2\', \'value3\         


        

Answer 1

Your query fails due to operator precedence. AND binds before OR!
You need a pair of parentheses, which is not a matter of "clarity", but pure logic necessity.

SELECT *
FROM   tbl_name
WHERE  other_condition = bar
AND    another_condition = foo
AND   (id_field IN ('value1', 'value2', 'value3') OR id_field IS NULL)

The added parentheses prevent AND binding before OR. If there were no other WHERE conditions (no AND) you would not need parentheses. The accepted answer is a bit misleading in this respect.