如何在一个表中一起添加两个查询？

Question

我有两个SQL查询,我想在同一个表上一起添加.我想显示一个显示JuniorCount,SeniorCount和DeptID的表.

现在我的查询计算了部门ECE的年级/高级,但我不知道如何将它们一起添加到单独的列以及deptid中.

SELECT COUNT(*) as JuniorCount
FROM (SELECT Class, DeptID FROM tblStudent WHERE Class = "Junior" AND DeptID = "ECE")


SELECT COUNT(*) as SeniorCount
FROM (SELECT Class, DeptID FROM tblStudent WHERE Class = "Senior" AND DeptID = "ECE")

Answer 1

这就是你需要的

SELECT DeptID,
sum(case when Class = 'Junior' then 1 else 0 end) as JuniorCount,
sum(case when Class = 'Senior' then 1 else 0 end) as SeniorCount
FROM 
tblStudent WHERE DeptID = 'ECE'
Group by DeptID

在MS ACCESS中

SELECT DeptID,
sum(IIF(Class = 'Junior' ,1,0)) as JuniorCount,
sum(IIF(Class = 'Senior' ,1,0)) as JuniorCount
FROM 
tblStudent WHERE DeptID = 'ECE'
Group by DeptID