用户登录存储过程

UserPower为用户的权限，我这里是int类型的。学生为0，老师为1，专家为3，管理员为4。

返回值是用户的状态，只不过状态中的值，有部分是用户的权限值。

CREATE proc Proc_UserLogin 
@UserName varchar(10),@UserPwd varchar(10),@UserPower int,@ReturnValues int output 
as 
begin
if @UserPower=0
if exists(select * from Student where Stu_ID=@UserName and Stu_Pwd=@UserPwd) 
begin 
select @ReturnValues=Stu_Power from Student where Stu_ID=@UserName and Stu_Pwd=@UserPwd
end 
else 
begin 
select @ReturnValues = -1 
end 

else if @UserPower=1
if exists(select * from Teacher where Tea_ID=@UserName and Tea_Pwd=@UserPwd) 
begin 
select @ReturnValues=Tea_Power from Teacher where Tea_ID=@UserName and Tea_Pwd=@UserPwd 
end 
else 
begin 
select @ReturnValues = -1 
end 

else if @UserPower=2
if exists(select * from Expert where Exp_ID=@UserName and Exp_Pwd=@UserPwd) 
begin 
select @ReturnValues=Exp_Power from Expert where Exp_ID=@UserName and Exp_Pwd=@UserPwd 
end 
else 
begin 
select @ReturnValues = -1 
end 

else if @UserPower=3
if exists(select * from Admin where Adm_ID=@UserName and Adm_Pwd=@UserPwd) 
begin 
select @ReturnValues=Adm_Power from Admin where Adm_ID=@UserName and Adm_Pwd=@UserPwd 
end 
else 
begin 
select @ReturnValues = -1 
end 

else
begin 
select @ReturnValues = -1 
end 

select @ReturnValues
end

declare @uid int 
exec Proc_UserLogin 'admin','admin',3,@uid