加入计数功能？ [英] count function in joining?

问题描述

  SELECT  tbl_Departments.DepartmentID，tbl_Departments.DepartmentName，count（tbl_LabourDetails.DepartmentID） as  labor 
  FROM  tbl_LabourDetails  RIGHT   OUTER   JOIN  
 tbl_Departments  ON  tbl_LabourDetails.DepartmentID = tbl_Departments.DepartmentID 

我试过这样但有一个例外：

列'tbl_Departments.DepartmentID'在选择列表，因为它不包含在聚合函数或GROUP BY子句中。

解决方案

您忘记了 GROUP BY 子句;添加

  GROUP   BY  tbl_Departments.DepartmentID，tbl_Departments.DepartmentName 

SELECT tbl_Departments.DepartmentID, tbl_Departments.DepartmentName, count(tbl_LabourDetails.DepartmentID ) as labour
FROM tbl_LabourDetails RIGHT OUTER JOIN
tbl_Departments ON tbl_LabourDetails.DepartmentID = tbl_Departments.DepartmentID

I have tried like this but there is an exception:

Column 'tbl_Departments.DepartmentID' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.

解决方案

You forgot the GROUP BY clause; add

GROUP BY tbl_Departments.DepartmentID, tbl_Departments.DepartmentName

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