สอบถามเกี่ยวกับ Error หน่อย ครับ ขอบคุณครับ C# กับ MySQL [arithmetic operation resulted in an overflow]

		String strConnString;
		strConnString = "Server=localhost;User Id=root; Password=root; Database=mydatabase; Pooling=false";
		objConn = new MySqlConnection(strConnString);
		objConn.Open();

		if(objConn.State == ConnectionState.Open)
		{
			this.lblText.Text = "MySql Connected";
		}
		else
		{
			this.lblText.Text = "MySql Connect Failed";
		}

String strConnString;
strConnString = "Server=localhost;User Id=root; Password=root; Database=mydatabase; Pooling=false";
objConn = new MySqlConnection(strConnString);
objConn.Open();

if(objConn.State == ConnectionState.Open)
{
	this.lblText.Text = "MySql Connected";
}
else
{
	this.lblText.Text = "MySql Connect Failed";
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using MySql.Data.MySqlClient;
using System.Windows.Forms;

namespace WindowsFormsApplication15
{
    public partial class Form1 : Form
    {
   
        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {
           
        }
        public bool tryLogin(string username, string password)
        {
            MySqlConnection con = new MySqlConnection("Server=localhost;user=root;password=042511827; database=voiceoperation;");
            MySqlCommand cmd = new MySqlCommand("SELECT * FROM login_test WHERE user_name = '" + username + "' AND user_pass = '" + password + "';");
            cmd.Connection = con;
            
            con.Open();

            MySqlDataReader reader = cmd.ExecuteReader();
            if (reader.Read() != false)
            {

                if (reader.IsDBNull(0) == true)
                {
                    cmd.Connection.Close();
                    reader.Dispose();
                    cmd.Dispose();
                    return false;
                }
                else
                {
                    cmd.Connection.Close();
                    reader.Dispose();
                    cmd.Dispose();
                    return true;
                }
            }
            else
            {
                return false;
            }
        }

        private void button3_Click(object sender, EventArgs e)
        {
            if (tryLogin(txtuser.Text, txtpass.Text) == true)
            {
                MessageBox.Show("Authed!");
            }
            else
            {
                MessageBox.Show("Auth Failure.");
            }
        }
    }
}
       

 private void Form1_Load(object sender, EventArgs e)
        {
            String strConnString;
            strConnString = "Server=localhost;User Id=root; Password=042511827; Database=voiceoperation; Pooling=false";
            objConn = new MySqlConnection(strConnString);
            objConn.Open();

            if (objConn.State == ConnectionState.Open)
            {
                this.lblText.Text = "MySql Connected";
            }
            else
            {
                this.lblText.Text = "MySql Connect Failed";
            }
        }
        void Form1_UnLoad()
        {
            objConn.Close();
            objConn = null;
        }