存储过程的问题

Question

请帮我看看这个存储过程有什么语法问题，应该改成什么样子呢?其实，我是想如果没有用户名/密码的话返回一个0，还有别的方法吗？谢谢！

ALTER PROCEDURE IsHaveUser
 (
 @UserName varchar(50),
 @Password varchar(50) OUTPUT
 )
AS
    declare @count int
 SET @Password= (SELECT Password FROM UserAndPassword WHERE UserName=@UserName)
 SET @count = (SELECT count(Password)
               FROM (SELECT (*)
                       FROM UserAndPassword
                       WHERE UserName = @UserName))
 RETURN @count

Answer 1

select 本就可以为变量赋值,既用set 又用select显然不对.将SET @count = (SELECT count(Password).........改为SELECT @count= count(Password).........