SQL在分支条件下联接表

Question

I'm trying to perform an SQL join "with a twist", something like this:

SELECT *
FROM a
JOIN b ON /* a.type == 'any' ? b.id IS NULL : b.id = a.id */

where the comment is written in C-like syntax. How can I express what I want in SQL? (Preferably ANSI, but specific to Oracle Database is fine too.)

Answer 1

SELECT *
FROM a
JOIN b ON (a.type  = 'any' AND b.id IS NULL) 
       OR (a.type <> 'any' AND b.id = a.id)