C#

private void button1_Click(object sender, EventArgs e)
        {
            try
            {
                string str = "provider=Microsoft.Jet.OLEDB.4.0;data source=1.mdb";
                OleDbConnection passconn = new OleDbConnection(str);
                string sql = "select * from password where username='" + this.textBox1.Text + "' and password ='" + this.textBox2.Text + "'";
                passconn.Open();
                OleDbCommand cmd = new OleDbCommand(sql, passconn);
                object result;
                result = cmd.ExecuteScalar();
                int myint = (int)result;
                if (myint == 1)
                {
                    this.Hide();
                    MDIParent mdi = new MDIParent();
                    mdi.Show();

                }
                else
                {
                    MessageBox.Show("Please enter the correct user name password");
                    textBox1.Text = "";
                    textBox2.Text = "";
                    textBox1.Focus();
                }
                passconn.Close();
                cmd.Dispose();
            }
                catch(OleDbException ex)
            {
                    MessageBox.Show(ex.Message);
            }
            }