Question

When trying to select fields from a subquery if ANY of the subqueries do not return any rows then nothing is returned (not even an empty result set)

SELECT sub1.field, sub2.another_field
    FROM (
        (
            SELECT field
            FROM table
            WHERE id=1
        ) AS sub1, (
            SELECT another_field
            FROM table
            WHERE id=2
        ) AS sub2
    )

I was hoping for a row containing a NULL value when a subquery return 0 rows.

Answer 1

You need to do an outer join as follows

SELECT sub1.field, sub2.another_field
FROM (
        SELECT field, id
        FROM tab1
        WHERE id=1
    ) AS sub1 LEFT OUTER JOIN (
        SELECT another_field, id
        FROM tab1
        WHERE id=2
    ) AS sub2
  ON sub1.id = 1 and sub2.id = 2