计数（*），不同和列

Question

如何在sqlserver中实现这一点

select firstname,count(*) from
(select distinct firstname,lastname,amount 
from emp)
group by firstname

这适用于oracle。

Answer 1

我不明白你想做什么，但你的查询可以这样写：

SELECT firstname, COUNT(*) 
FROM emp
GROUP BY firstname;

或

select firstname, count(*) 
from 
(
  select distinct firstname, lastname, amount 
  from emp
) AS t
group by firstname;

您还可以使用DISTINCT内的COUNT关键字;像这样：COUNT(DISTINCT columnanme)代替。

---

或

select firstname, lastname, amount, COUNT(*)
from emp
group by firstname, lastname, amount;

Answer 2

以下是一些我工作的东西的例子基本上是一样的：

SELECT SYS_CSL, COUNT(SYS_CSL)
FROM (
    SELECT SYS_CSL 
    FROM [VANTAGE_READ].CSL_SERV_RANK
    WHERE AGNT_CSL = 0
    AND (STOP_DTE_CSL > GETDATE() OR STOP_DTE_CSL IS NULL)
    ) t1 GROUP BY sys_csl

Answer 3

您需要命名派生表

select firstname, count(*)  
from  (select distinct firstname,lastname,amount from emp) derived 
group by firstname