如何返回计数而不计入SQL查询？

Question

如果我有一张桌子

AgentID | IsNew | TeamID
1         N       1
2         Y       2
3         Y       2
4         N       2
5         Y       1

我想从查询中返回以下内容：

Team | CountIsNew = N | CountIsNew = Y
1      1                1
2      1                2

有没有办法可以做到这一点？
使用Oracle 10

Answer 1

SELECT  team, SUM(DECODE(IsNew, 'N', 1, 0)), SUM(DECODE(IsNew, 'Y', 1, 0))
FROM    mytable
GROUP BY
        team

Answer 2

SELECT TeamId
     , SUM(CASE WHEN IsNew = 'N' THEN 1 ELSE 0 END) AS CountIsNotNew
     , SUM(CASE WHEN IsNew = 'Y' THEN 1 ELSE 0 END) AS CountIsNew
FROM Agent
GROUP BY TeamId

Answer 3

另一种方式 - COUNT不计算NULL（ COUNT(*)除外）：

SELECT TeamId,
       COUNT(DECODE(IsNew,'N',1)) CountIsNotNew,
       COUNT(DECODE(IsNew,'Y',1)) CountIsNew
FROM Agent
GROUP BY TeamId;

或者，如果您更喜欢CASE：

SELECT TeamId,
       COUNT(CASE IsNew WHEN 'N' THEN 1 END) CountIsNotNew,
       COUNT(CASE IsNew WHEN 'Y' THEN 1 END) CountIsNew
FROM Agent
GROUP BY TeamId;

（注意：“1”可以是任何字面值）