สอบถามเรื่องการ Insert ค่าลงดาต้าเบสของ mysql หน่อยครับ มันบอกว่า colum userlogin ว่างอ่ะครับแก้ไขยังครับ

                    strSQL = "UPDATE files SET FilesName = ?sFilesName , FilesType = ?sFilesType WHERE FilesID = ?sFilesID ";

                    objCmd = new MySqlCommand(strSQL, objConn);
                    objCmd.Parameters.Add("?sFilesName", MySqlDbType.Binary).Value = imbByte;
                    objCmd.Parameters.Add("?sFilesType", MySqlDbType.VarChar).Value = strMIME;
                    objCmd.Parameters.Add("?sFilesID", MySqlDbType.Int32).Value = Request.QueryString["FilesID"];
                    objCmd.ExecuteNonQuery();

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Configuration;
using MySql.Data.MySqlClient;
public partial class admin_add_Member : System.Web.UI.Page
{
    MySqlConnection ObjCon;
    protected void Page_Load(object sender, EventArgs e)
    {
            btnSave.Attributes.Add("Onclick", "return ChkData();");
            String StringCon;
            StringCon = ConfigurationManager.ConnectionStrings["ConectDB"].ConnectionString;
            ObjCon = new MySqlConnection(StringCon);
            ObjCon.Open(); 
     }
    protected void btnSave_Click(object sender, EventArgs e)
    {
        //StrInsert += " VALUES (NULL,'" + username.Text.Trim() + "','" + password.Text.Trim() + "','" + name.Text.Trim() + "','Y',curdate()) ";
        //   Response.Write(StrInsert);
        String StrInsert;
        StrInsert = "INSERT INTO member(id_mem,userlogin,pass,name,isactive,datesave)";
        StrInsert += "VALUES(@id_mem,@userlogin,@pass,@name,@isactive,curdate())";
        MySqlCommand SqlInsert = new MySqlCommand(StrInsert, ObjCon);
         SqlInsert.CommandText = StrInsert;
         SqlInsert.Parameters.Add("@id_mem", MySqlDbType.Int32).Value=null;
        SqlInsert.Parameters.Add("@userlogin",MySqlDbType.VarChar).Value =username.Text.Trim();
        SqlInsert.Parameters.Add("@pass", MySqlDbType.VarChar).Value = password.Text.Trim();
        SqlInsert.Parameters.Add("@name", MySqlDbType.VarChar).Value = name.Text.Trim();
        if (isactive.Checked)
        {
            SqlInsert.Parameters.Add("@isactive",MySqlDbType.Char).Value="Y";
        }
        else
        {
            SqlInsert.Parameters.Add("@isactive", MySqlDbType.Char).Value = "N";
        }
        SqlInsert.ExecuteNonQuery();
    }
}