sql: where 中 case

select count(*)
  from change_record cr
 where 1 = 1
   and cr.change_status_id = 29
   and cr.testers = 'yhl'
   and (case cr.change_record_res_id when 1 then
        (select bug.bug_status_id
           from bug_record bug
          where bug.bug_id = cr.origin_source_id) when 2 then
        (select req.req_status_id
           from requirement_record req
          where req.req_id = cr.origin_source_id) else 0 end) in (4, 24)