SQL質疑応答スレ 18問目

[0045 NAME IS NULL 2018/02/22(木) 18:10:39.74 ID:???]

>>44
CASE式で

SELECT c1,
CASE (SELECT count( * ) FROM t1 AS a WHERE a.c1 = b.c1 AND c2 IS NULL)
WHEN 0 THEN sum(c2)
ELSE 0 END
FROM t1 AS b
GROUP BY c1

設計見なおしたほうがいいパターンだと思う