conform password

private void button2_Click(object sender, EventArgs e)
        {
            try
            {
                string d = "select name,pass from pass where name='" + label1.Text + "' and pass='" + textBox6.Text + "'";
                SqlCommand cmd1 = new SqlCommand(d, con);
                con.Open();
                SqlDataReader dr = cmd1.ExecuteReader();
               
                if (dr.Read() == true)

                {
                    dr.Close();
                    if (textBox3.Text == textBox4.Text)
                    {
                       
                        string s = "update pass set pass='" + textBox4.Text + "' where pass='" + textBox6.Text + "' and name='" + label1.Text + "'";
                        SqlCommand cmd = new SqlCommand(s,con);
                       
                        cmd.ExecuteNonQuery();
                    
                       
                        MessageBox.Show("entered succesfully");
                       
                    }
                    else
                    {
                        MessageBox.Show("password mismatch");
                    }
                }
                else
                {
                    MessageBox.Show("invalid currentpassword");
                }

            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                con.Close();
            }
        }