存储过程不 return 输出

Question

我有一个简单的存储过程，它在 table 中插入一条用户记录，并且应该给出它的用户 ID。

存储过程如下：

 Alter proc spRegistration
     @UserId nvarchar(10) output,
     @Name nvarchar(20),
     @EmailAdd nvarchar(20)
 as
 begin
     Declare @Count int;
     Declare @ReturnCode int

     Select @Count = Count(EmailAdd) 
     from tblAllUsers 
     where EmailAdd = @EmailAdd

     if @Count > 0
     begin
         Set @ReturnCode = -1
     end
     else
     begin
         Set @ReturnCode = 1

         Insert into tblAllUsers(Name, EmailAdd) 
         values(@Name, @EmailAdd)
     end

     Select @UserId = UserId 
     from tblAllUsers 
     where EmailAdd = @EmailAdd

     Select @ReturnCode as ReturnCode
 end

我尝试将 userid 放入如下所示的文本框中：

 string CS = ConfigurationManager.ConnectionStrings["hh"].ConnectionString;
    using (SqlConnection con = new SqlConnection(CS))
    {
        con.Open();
        SqlCommand cmd = new SqlCommand("spRegistration", con);
        cmd.CommandType = CommandType.StoredProcedure;
        cmd.Parameters.AddWithValue("@Name", txtName.Text);
        cmd.Parameters.AddWithValue("@EmailAdd", txtEmailAddress.Text);
        var UserID = cmd.Parameters.AddWithValue("@UserId", SqlDbType.NVarChar);
        UserID.Direction = ParameterDirection.Output;
        int ReturnCode = (int)cmd.ExecuteScalar();
        if (ReturnCode == -1)
        {
            lblRegMessage.Text = "This email has already been registered with us.";
        }
        else
        {
            lblRegMessage.Text = "You were registered successfully.";
            txtUserId.Text=(String)UserID.Value;
        }

table以及存储过程太复杂了，我简化了它以便更好地理解problem.UserId是Alphanumeric.Dont担心的

放置一个断点显示 var UserID 为空我哪里错了？

Answer 1

您需要在 UserID

上使用 .ToString()

txtUserId.Text= UserID.Value.ToString();

编辑：

var UserID = cmd.Parameters.AddWithValue("@UserId", SqlDbType.NVarChar,50);

存储过程不 return 输出

Stored procedure doesn't return output

sql-server

asp.net

stored-procedures