SELECT a.sn, nvl(MAX(t.ok), 0) ok, a.name
FROM tb_A a,
(SELECT b.sn,
SUM(CASE WHEN b.ok = 'Y' THEN 1 ELSE 0 END) as ok
FROM TB_B b
WHERE ok IS not NULL
GROUP BY b.sn) c
WHERE a.sn = c.sn(+)
and ok > 0
GROUP BY a.sn;
1행에 a.name 이란걸 추가하면
ORA-00979: not a GROUP BY expression
00979. 00000 - "not a GROUP BY expression"
그룹바이 표현이 아니라고 뜨는데 어떻게 해줘야 name을 추가할수 있나요??