form1 codes

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

namespace music
{
    public partial class Form1 : Form
    {
        SqlDataAdapter da = new SqlDataAdapter();
        DataSet ds = new DataSet();

        SqlConnection con = new SqlConnection("Data Source=.\\SQLEXPRESS;AttachDbFilename=|DataDirectory|\\sazdb.mdf;Integrated Security=True;Connect Timeout=30;User Instance=True");
        SqlCommand cm = new SqlCommand();
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            con.Open();
            da = new SqlDataAdapter("select * from addmin ", con);

            ds.Reset();
            da.Fill(ds, "addmin");

            da.SelectCommand = cm;


            if (textBox3.Text == Convert.ToString(ds.Tables["addmin"].Rows[0][0]) &&
                textBox4.Text == Convert.ToString(ds.Tables["addmin"].Rows[0][1]))
            {
                Form objform1 = new main();

                objform1.Show();


            }

            else
            {
                if (textBox3.Text != Convert.ToString(ds.Tables["addmin"].Rows[0][0]))
                    MessageBox.Show("نام کاربری اشتباه است ");
                if (textBox4.Text != Convert.ToString(ds.Tables["addmin"].Rows[0][1]))
                    MessageBox.Show("کلمه عبور اشتباه است");
            }
            con.Close();

        }

        private void button2_Click(object sender, EventArgs e)
        {
            con.Open();
            da = new SqlDataAdapter("select * from honarjoo where code='" + textBox2.Text + "'", con);
            ds.Reset();
            da.Fill(ds, "honarjoo");

            da.SelectCommand = cm;


            if (textBox2.Text == Convert.ToString(ds.Tables["honarjoo"].Rows[0][4]))
            {
                Form objform1 = new honarjoo();

                objform1.Show();


            }

            else
            {
                if (textBox2.Text != Convert.ToString(ds.Tables["honarjoo"].Rows[0][4]))
                    MessageBox.Show("رمز اشتباه است ");

            }



            con.Close();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            if (MessageBox.Show("آیا قصد خروج از برنامه را دارید؟", "", MessageBoxButtons.YesNo, MessageBoxIcon.Information) == DialogResult.Yes)
                this.Close();
        }
    }
}