COUN（*），不同的和列

Question

如何完成这样的在SQLSERVER

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

这工作在oracle中。

Answer 1

我不明白你有什么做的，但你的查询可以这样写：

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

或者：

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

您也可以使用关键字DISTINCT在COUNT之内;像这样：COUNT(DISTINCT columnanme)。

---

或者：

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

Answer 2

下面是一些东西的例子，我的工作，基本上做同样的事情：

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