正在执行SPROC-返回值=-1

我设置了一个SPROC来验证登录凭据，但当我从代码中执行它时，似乎无法让它返回正确的值。当我尝试从C#执行它时，即使我输入了正确的用户名和密码组合，它也会不断返回值"-1"，但当我直接从SSMS执行时，它运行得非常好。

SPROC

USE [database]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROC [dbo].[usp_ReadUserLogin]
  @LoginUsername VARCHAR(50),
  @LoginPassword VARCHAR(100)
AS
BEGIN
  SET NOCOUNT ON;
  DECLARE @Salt CHAR(25);
  DECLARE @PasswordSalt VARCHAR(125);
  DECLARE @PasswordHash VARBINARY(255);  
  SELECT @Salt = [dbo].[users].[salt], @PasswordHash = [dbo].[users].[password] 
  FROM [dbo].[users] WHERE [dbo].[users].[username] = @LoginUsername;
  SET @PasswordSalt = @Salt + @LoginPassword;
  IF (HASHBYTES('SHA2_512', @PasswordSalt) = @PasswordHash)
    RETURN 0; /*Match*/
  ELSE
    RETURN 1; /*No Match*/    
END;
GO

控制器

    [HttpPost]
    [ValidateAntiForgeryToken]
    public ActionResult Login(User u)
    {
        if (ModelState.IsValid) // this is check validity
        {
            using (WebFTS.Models.webftsEntities db = new WebFTS.Models.webftsEntities())
            {
                //Method 1 - Still returns value = -1
                //var sql = "EXEC [dbo].[usp_ReadUserLogin] @LoginUsername, @LoginPassword";
                //var usernameParam = new SqlParameter("@LoginUsername", u.username);
                //var passwordParam = new SqlParameter("@LoginPassword", u.password);
                //var query = db.Database.ExecuteSqlCommand(sql, usernameParam, passwordParam);
                //Method 2 - Still returns value = -1
                var query = db.usp_ReadUserLogin(u.username, u.password);
                if (query != 0)
                {
                    ViewBag.message = "Incorrect username and/or password.";
                }
                else
                {
                    var d = db.users.Where(model => model.username.Equals(u.username)).FirstOrDefault(); 
                    if (d != null)
                    {
                        Session["lid"] = d.user_id.ToString();
                        Session["lun"] = d.username.ToString();
                        return RedirectToAction("AfterLogin");
                    }
                }
            }                
        }
        return View(u);
    }

查看

     <div style="margin-right:auto; margin-left:auto;">
         <table style="overflow:hidden;">
             <tr>
                 <td>Username</td>
                 <td>@Html.TextBoxFor(a => a.username)</td>
                 <td><b>@Html.ValidationMessageFor(a => a.username)</b></td>
             </tr>
             <tr>
                 <td>Password</td>
                 <td>@Html.PasswordFor(a => a.password)  </td>
                 <td><b>@Html.ValidationMessageFor(a => a.password)</b></td>
             </tr>
             <tr>
                 <td></td>
                 <td></td>
                 <td align="right"><input type="submit" value="Login" class="button" /></td>                 
             </tr>
         </table>
     </div>    

如有任何帮助，我们将不胜感激。非常感谢。

SPROC（更新）

USE [database]
GO
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROC [dbo].[usp_ReadUserLogin]
  @LoginUsername VARCHAR(50),
  @LoginPassword VARCHAR(100)
AS
BEGIN
  --SET NOCOUNT ON;
  DECLARE @userid INT;
  DECLARE @Salt CHAR(25);
  DECLARE @PasswordSalt VARCHAR(125);
  DECLARE @PasswordHash VARBINARY(255);  
  SELECT @userid = [dbo].[users].[user_id], @Salt = [dbo].[users].[salt], @PasswordHash = [dbo].[users].[password]  
  FROM [dbo].[users] WHERE [dbo].[users].[username] = @LoginUsername;
  SET @PasswordSalt = @Salt + @LoginPassword;
  IF (HASHBYTES('SHA2_512', @PasswordSalt) = @PasswordHash)
     SELECT @userid; /*Match*/
  ELSE
     SELECT 0; /*No Match*/   
END;
GO

控制器（更新）

System.Nullable<int> query = db.ReadUserLogin(u.username, u.password).SingleOrDefault();
if (query == 0)
    ViewBag.message = "Incorrect username and/or password.";
else if (query.HasValue)
{
     //follow the rest of the code to select the user.
}

多亏了Dude Pascalou我才得以解决我的问题。他提供的链接就是答案。我还更新了代码，所以如果有人需要它，他们可以看到之前和之后。感谢您的帮助！