LOAD DATA FROM SQL TABLE AND MULTIPLY QUNTY AND RATE

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 CCornerItemDemo
{
    public partial class Form1 : Form
    {
        SqlConnection conn;
        SqlDataAdapter da;
        DataSet ds;
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            conn = new SqlConnection("data source=.;initial catalog=ranjit;integrated security=true");
            da = new SqlDataAdapter("select Items from Items",conn );
            ds = new DataSet();
            da.Fill(ds);

            label1.Text = ds.Tables[0].Rows[0]["Items"].ToString();
            label2.Text = ds.Tables[0].Rows[1]["Items"].ToString();
            label3.Text = ds.Tables[0].Rows[2]["Items"].ToString();
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {
            da = new SqlDataAdapter("select Rate from Items Where sno=1", conn);
            ds = new DataSet();
            da.Fill(ds);
            double rate = Convert.ToDouble(ds.Tables[0].Rows[0]["Rate"].ToString());
            double qty;
            if (string.IsNullOrEmpty(textBox1.Text))
            {
                qty = 0;
            }
            else
            qty = Convert.ToDouble(textBox1.Text );
            label6.Text = (rate * qty).ToString();
        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {
            da = new SqlDataAdapter("select Rate from Items Where sno=2", conn);
            ds = new DataSet();
            da.Fill(ds);
            double rate = Convert.ToDouble(ds.Tables[0].Rows[0]["Rate"].ToString());
            double qty;
            if (string.IsNullOrEmpty(textBox2.Text))
            {
                qty = 0;
            }
            else
                qty = Convert.ToDouble(textBox2.Text);
            label5.Text = (rate * qty).ToString();
        }

        private void textBox3_TextChanged(object sender, EventArgs e)
        {
            da = new SqlDataAdapter("select Rate from Items Where sno=3", conn);
            ds = new DataSet();
            da.Fill(ds);
            double rate = Convert.ToDouble(ds.Tables[0].Rows[0]["Rate"].ToString());
            double qty;
            if (string.IsNullOrEmpty(textBox3.Text))
            {
                qty = 0;
            }
            else
                qty = Convert.ToDouble(textBox3.Text);
            label4.Text = (rate * qty).ToString();
        }

      
    }
}