问PostgreSQL子查询

EN

SELECT y.*
FROM (
   SELECT distinct subject
   FROM table1
) x,
LATERAL (
  SELECT * FROM table1 t
  WHERE t.subject = x.subject
  ORDER BY id, num
  LIMIT 1
) y
order by 1

| subject | id | num | code |
|---------|----|-----|------|
|       2 | 34 |   3 | 1267 |
|       3 | 23 |  16 | 4568 |
|       5 | 29 |  53 | 2354 |

SELECT * 
FROM ztable zt
WHERE NOT EXISTS(
        SELECT * FROM ztable nx
        WHERE nx.subject = zt.subject
        AND nx.num < zt.num
        AND nx.id < zt.id
        );