Question

SQL SELECT语句中嵌入多重选择，用if语句

我是这样写的，不知道哪里错了
USE YGGL
GO
SELECT EmployeeID,Name,Address,DepartmentID=
(
IF (SELECT DepartmentID FROM Employees)='1' BEGIN RETURN '财务部' END
IF (SELECT DepartmentID FROM Employees)='2' BEGIN RETURN '人力资源部' END
IF (SELECT DepartmentID FROM Employees)='3' BEGIN RETURN '经理办公室' END
IF (SELECT DepartmentID FROM Employees)='4' BEGIN RETURN '研发部' END
IF (SELECT DepartmentID FROM Employees)='5' BEGIN RETURN '市场部' END
)
FROM Employees
使用CASE对Employees表按部门进行分类：
USE YGGL
GO
SELECT EmployeeID ，Name，Address，DepartmentID=
CASE DepartmentID
WHEN 1 THEN ‘财务部’
WHEN 2 THEN ‘人力资源部’
WHEN 3 THEN ‘金理办公室’
WHEN 4 THEN ‘研发部’
WHEN 5 THEN ‘市场部’
END
FROM Employees
练习： 使用IF语句实现上述功能

Answer 1

SELECT EmployeeID,Name,Address,

case when DepartmentID ='1' then '财务部'
when DepartmentID ='2' then '人力资源部'
when DepartmentID = '3' then '经理办公室'
when DepartmentID ='4' then '研发部'
when DepartmentID = '5' then '市场部' END as DepartmentID
FROM Employees

Answer 2

用case,这样写就可以了

USE YGGL
GO
SELECT EmployeeID,Name,Address,
Department=
(
case DepartmentID
when '1' then '财务部'
when '2' then '人力资源部'
when '3' then '经理办公室'
when '4' then '研发部'
when '5' then '市场部'
end
)
FROM Employees

如果DepartmentID是int，那1，2，3，4，5不要加引号

Answer 3

SELECT EmployeeID,Name,Address,
decode(DepartmentID ,'1' ,'财务部'
,'2' ,'人力资源部'
,'3', '经理办公室'
,'4', '研发部'
,'5','市场部')as DepartmentID
FROM Employees

Answer 4

IF 后面要true或者false
IF EXISTS(SELECT DepartmentID FROM Employees='1') ....
看行不?

Answer 5

不要用等号，用as或者用空格试一下