Question

让我们说我在呼叫中心工作，我关闭了10个电话但当天打了20个电话。 “真实”的数字实际上是-10。即使目标是10次关闭调用，工作人员也会失败，因为打开了20个调用。

我想写一份SQL报告来反映这一点。但我的问题似乎是我无法从总计数中计算数字。

SELECT workername                       AS Name, 
       (SELECT Count(closeddate) 
        FROM   mybanksupport 
        WHERE  closeddate = NULL)       OPENCALLS, 
       (SELECT Count(closeddate) 
        FROM   mybanksupport 
        WHERE  closeddate = NOT NULL)   CLOSEDCALLS, 
       (SELECT opencalls - closedcalls) REALCALLS 
FROM   mybanksupport

简而言之，我想计算2个列计数值，然后使用该值生成另一个名为Real Calls的计算列

Answer 1

COUNT仅计算值，即忽略NULL s。此属性可用于简单表达：

SELECT workername, closedCalls, totalCalls - closedCalss AS openCalls
FROM   (SELECT   workername, COUNT(closeddate) AS closedcalls, COUNT(*) totalCalls
        FROM     mybanksupport
        GROUP BY workername) t

Answer 2

写为子查询，然后您可以根据需要使用字段表单

Select
  workername
, OPENCALLS
, CLOSEDCALLS
, (OPENCALLS - CLOSEDCALLS)  REALCALLS
From
(
SELECT workername                       AS Name, 
       (SELECT Count(closeddate) 
        FROM   mybanksupport 
        WHERE  closeddate = NULL)       OPENCALLS, 
       (SELECT Count(closeddate) 
        FROM   mybanksupport 
        WHERE  closeddate = NOT NULL)   CLOSEDCALLS, 
FROM   mybanksupport 
) T1

使用SQL COUNT创建计算列

2 个答案: