如何在一个 SELECT 语句中使用两个或多个 ACCOUNT？答案

【问题标题】：How can I use two or more COUNT()s in one SELECT statament?如何在一个 SELECT 语句中使用两个或多个 ACCOUNT？
【发布时间】：2010-03-17 05:42:22
【问题描述】：

我开发了这段代码：

SELECT COUNT(NewEmployee.EmployeeID), NewEmployee.EmployeeId,EmployeeName 
FROM NewEmployee INNER JOIN NewTimeAttendance  
  ON NewEmployee.EmployeeID = NewTimeAttendance.EmployeeID 
  and NewTimeAttendance.TotalTime is  null 
  and (NewTimeAttendance.note = '' or NewTimeAttendance.note is null)
  and (month = 1 or month = 2 or month = 3)  
GROUP BY NewEmployee.EmployeeID, EmployeeName
order by EmployeeID

根据我之前的两个问题 selecting null stuff 和 counting issue...令人惊叹的代码运行良好...但现在我需要 select 更多不止一个count...

...搜索（谷歌）....找到alias...尝试：

SELECT COUNT(NewEmployee.EmployeeID) as attenddays, COUNT(NewEmployee.EmployeeID) as empabsent
 , NewEmployee.EmployeeId,EmployeeName 
 FROM NewEmployee INNER JOIN NewTimeAttendance  
  ON empabsent =NewEmployee.EmployeeID = NewTimeAttendance.EmployeeID 
  and NewTimeAttendance.TotalTime is  null 
  and (NewTimeAttendance.note = '' or NewTimeAttendance.note is null )
    and (month=1 or month =2 or month = 3) , 
    attenddays = NewTimeAttendance.EmployeeID 
  and NewTimeAttendance.TotalTime is  null 
  and (NewTimeAttendance.note = '' or NewTimeAttendance.note is null )
    and (month=1 or month =2 or month = 3)
GROUP BY NewEmployee.EmployeeID, EmployeeName  order by EmployeeID

Incorrect syntax near '='.

第二次尝试：

SELECT COUNT(NewEmployee.EmployeeID) as attenddays, COUNT(NewEmployee.EmployeeID) as absentdays,
NewEmployee.EmployeeId,EmployeeName 
FROM NewEmployee INNER JOIN NewTimeAttendance  
  ON attenddays(NewEmployee.EmployeeID = NewTimeAttendance.EmployeeID 
  and NewTimeAttendance.TotalTime is  null 
  and (NewTimeAttendance.note = '' or NewTimeAttendance.note is null )
  and (month=1 or month =2 or month = 3)) ,
  absentdays(NewEmployee.EmployeeID = NewTimeAttendance.EmployeeID 
  and NewTimeAttendance.TotalTime is  null 
  and (NewTimeAttendance.note = '' or NewTimeAttendance.note is null )
  and (month=1 or month =2 or month = 3))
GROUP BY NewEmployee.EmployeeID, EmployeeName  order by EmployeeID

Incorrect syntax near '='.

不是很好的想法...所以...帮助

我想要的只是count 不同条件的ID...

COUNT(NewEmployee.EmployeeID)
ON NewEmployee.EmployeeID = NewTimeAttendance.EmployeeID 
  and NewTimeAttendance.TotalTime is  null 
  and (NewTimeAttendance.note = '' or NewTimeAttendance.note is null )
  and (month=1 or month =2 or month = 3)

和

COUNT(NewEmployee.EmployeeID)
ON NewEmployee.EmployeeID = NewTimeAttendance.EmployeeID 
  and NewTimeAttendance.TotalTime is not  null 
  and (NewTimeAttendance.note = '' or NewTimeAttendance.note is null )
  and (month=1 or month =2 or month = 3)

在同一个选择语句中。

提前致谢

【问题讨论】：

标签： sql join count

【解决方案1】：

您似乎正试图找出每位员工出勤和缺勤的天数。我会推荐这样的查询：

SELECT EmployeeId, EmployeeName,
    (SELECT COUNT(*)
     FROM NewTimeAttendance
     WHERE NewTimeAttendance.EmployeeID = NewEmployee.EmployeeId
         /* include condition for employee in attendance */
         AND TotalTime IS NULL
         AND (Note = '' or Note IS NULL)
         AND Month BETWEEN 1 AND 3) AS AttendDays,
    (SELECT COUNT(*)
     FROM NewTimeAttendance
     WHERE NewTimeAttendance.EmployeeID = NewEmployee.EmployeeId
         /* include condition for employee absent */
         AND TotalTime IS NULL
         AND (Note = '' or Note IS NULL)
         AND Month BETWEEN 1 AND 3) AS AbsentDays
FROM NewEmployee
ORDER BY EmployeeID

【讨论】：

wooow..你理解我..谢谢你..还有很好的编码..谢谢你......你知道......我在考虑两个选择，但我使用了别名。 . 你很聪明....谢谢

【解决方案2】：

第一个查询由于 ON 子句中的一堆错误而引发语法错误。也就是说：

1. empabsent =NewEmployee.EmployeeID = NewTimeAttendance.EmployeeID 
2. and (month=1 or month =2 or month = 3) , attenddays = NewTimeAttendance.EmployeeID

在第二个查询中，AttendDays 和 AbsentDays 应该是用户定义的函数吗？如果是的话，我无法想象这种语法在任何 SQL 方言中都有效。

您到底想达到什么目的？你要数什么？您能否提供两条不同的 SQL 语句，分别为您提供所需的计数，然后我们可以尝试将它们组合起来？

编辑鉴于新信息，您应该能够在单个查询中执行此操作：

SELECT EmployeeId, EmployeeName
    , Sum(Case When NewTimeAttendence.TotalTime Is Null Then 1 Else 0 End) As AttendDays
    , Sum(Case When NewTimeAttendence.TotalTime Is Not Null Then 1 Else 0 End) As AbsentDays
FROM NewEmployee
    Join NewTimeAttendence
        On NewTimeAttendence.EmployeeId = NewEmployee.EmployeeeId
Where (NewTimeAttendence.Note = '' Or NewTimeAttendence.Note Is Null)
    And Month In(1,2,3)
Group By EmployeeId, EmployeeName

【讨论】：