存储过程中的返回计数 [英] Return count in Stored Procedure

问题描述

我写了一个存储过程来返回一个计数.但我得到了一个空值.谁能告诉我我的存储过程中的问题在哪里.

I wrote a stored procedure to return a count. But I got a null value. Can anybody tell me where is the problem in my stored procedure.

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go

ALTER PROCEDURE [dbo].[ValidateUser]
@UserName varchar(50),
@Password varchar(50),
@Num_of_User int output

AS 
BEGIN
  SET NOCOUNT ON;

  SELECT @Num_of_user =COUNT(*) 
    FROM login
   WHERE username = @UserName 
     AND pw = @Password

  RETURN

END

推荐答案

您正在将值设置到变量 @num_of_user 中.在查询后添加 select @num_of_user

you are setting the value into the variable @num_of_user. add select @num_of_user after the query

set ANSI_NULLS ON
set QUOTED_IDENTIFIER ON
go


ALTER PROCEDURE [dbo].[ValidateUser]
    @UserName varchar(50),
    @Password varchar(50),
    @Num_of_User int output

AS
BEGIN
    SET NOCOUNT ON;
     SELECT @Num_of_user =COUNT(*) 
         FROM login
         WHERE username=@UserName AND pw=@Password

     SELECT @Num_of_user
return
END

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