IF语句中的简单赋值问题

[zjroland]

create PROCEDURE [dbo].[up_Teachers_GetUserDemandInfoByUserID]
@UserID int
AS

DECLARE @GroupUserID int,@TeacherUserID int,@Occupation NVARCHAR(50)
SELECT @GroupUserID = UserID FROM Groups_Groups WHERE UserID=@UserID
SELECT @TeacherUserID = UserID FROM Teachers_Teachers WHERE UserID=@UserID
IF (@GroupUserID>0)
@Occupation = '商户'
ELSE IF (@TeacherUserID>0)
@Occupation = '老师'
ELSE
@Occupation = '学生'

这么简单的存储过程竟然报错：
消息 102，级别 15，状态 1，“@Occupation”附近有语法错误。
消息 102，级别 15，状态 1，“@Occupation”附近有语法错误。

这是怎么回事？正确的应该怎么写？

[中国风]

或用CASE WHEN ...END e.g.

create PROCEDURE [dbo].[up_Teachers_GetUserDemandInfoByUserID]
@UserID int
AS

DECLARE @GroupUserID int,@TeacherUserID int,@Occupation NVARCHAR(50)
SELECT @GroupUserID = UserID FROM Groups_Groups WHERE UserID=@UserID 
SELECT @TeacherUserID = UserID FROM Teachers_Teachers WHERE UserID=@UserID 

SET @Occupation=CASE WHEN @GroupUserID>0 THEN '商户' WHEN @TeacherUserID>0 THEN '老师' ELSE '学生'  END

[二月十六]

CREATE PROCEDURE [dbo].[up_Teachers_GetUserDemandInfoByUserID] @UserID INT
AS
    DECLARE @GroupUserID INT ,
        @TeacherUserID INT ,
        @Occupation NVARCHAR(50)
    SELECT  @GroupUserID = UserID
    FROM    Groups_Groups
    WHERE   UserID = @UserID 
    SELECT  @TeacherUserID = UserID
    FROM    Teachers_Teachers
    WHERE   UserID = @UserID 
    IF ( @GroupUserID > 0 )
        SET @Occupation = '商户'
    ELSE
        IF ( @TeacherUserID > 0 )
            SET @Occupation = '老师'
        ELSE
            SET @Occupation = '学生' 

[zjroland]

原来是少了个SET，我把C#的编程习惯用到SQL 了，多谢

[zjroland]

原来是少了个SET，我把C#的编程习惯用到SQL 了，多谢