Question

我有一个表c，其中包含以下列

T1

我必须选择C1 SeqNo C2 ID 1 1 10 abc 1 1 20 xyz 1 1 30 mn0 1 2 10 123 1 3 10 abc 1 3 20 xyz 2 1 10 a1c 2 2 10 x1z 2 2 20 m10 2 2 30 1k3 2 3 10 a1c 2 3 20 x1z其中ID为最大值，SeqNo为每个不同值C1的最大值C2

结果应该是：

seqNo

如果有人可以提供帮助，请

Answer 1

您需要的只是具有MAX聚合函数的GROUP BY子句：

SELECT id, MAX(rev) FROM YourTable GROUP BY id ...

Answer 2

SELECT C1, SeqNo, MAX(C2), ID
  FROM T1
 WHERE C1 = 1
 GROUP BY SeqNo
 ORDER BY SeqNo DESC
 LIMIT 1;

Answer 3

db2中的

select C1, ID, Max(SeqNo) as SeqNo, Max(C2) as C2
from yourtable
where C1=1
group by C1, ID
order by 3 desc, 4 desc, 2 desc
fetch first rows only

Answer 4

DB2中的其他解决方案

select * from (
select f1.*, rownumber() over(order by SeqNo desc, C2 desc, ID desc) rang
from yourtable f1 where f1.C1=1
) tmp where tmp.rang=1

选择具有最大值的行

4 个答案: