how to insert from gridview textbox in asp.net.

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="Editable_GridView_multiple_records.WebForm1" %>





   


   

   

                                 AllowPaging="True"
                             DataSourceID="SqlDataSource1"
                             AutoGenerateColumns="false">

 
    
 
   
   
                      AutoPostBack="true"
             OnCheckedChanged="chkSelect_CheckedChanged"/>
   
   
   
                                       SortExpression="ID"/>
                                  
                           SortExpression="PRSL">
   
                     Text='<%# Bind("PRSL") %>' ReadOnly="true"
                 ForeColor="Blue" BorderStyle="none"
                 BorderWidth="0px" >
   
   
   
   
   
                           SortExpression="Quantity">
   
                     Text='<%# Bind("Quantity") %>'
                 ReadOnly="true" ForeColor="Blue"
                 BorderStyle="none" BorderWidth="0px">
   
   
   
   
   
                           SortExpression="Price">
   
                     Text='<%# Bind("Price") %>'
                 ReadOnly="true" ForeColor="Blue"
                 BorderStyle="none" BorderWidth="0px">
   
   
   
   
   
   
                           SortExpression="Unit">
   
                     Text='<%# Bind("Unit") %>'
                 ReadOnly="true" ForeColor="Blue"
                 BorderStyle="none" BorderWidth="0px">
   
   
   
   
   
   
   



ConnectionString="<%$ ConnectionStrings:ConnectionString %>"
SelectCommand="SELECT [ID], [PRSL], [Quantity], [Price], [Unit] FROM [product]"
DeleteCommand="DELETE FROM product WHERE (ID = @ID)"
UpdateCommand="UPDATE [product] SET [PRSL] = @PRSL,
              [Quantity] = @Quantity,[Price] = @Price,[Unit] = @Unit WHERE [ID] = @ID">
       
            
       
       
               
               
               
               
               
       
       

       
            OnClick="btnUpdate_Click" Text="Save" />

           

   

   

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Data.SqlClient;
using System.Text;

namespace Editable_GridView_multiple_records
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        string connStr = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;

      
        protected void btnUpdate_Click(object sender, EventArgs e)
        {
            StringBuilder strSql = new StringBuilder(string.Empty);

            SqlConnection con = new SqlConnection(connStr);
            SqlCommand cmd = new SqlCommand();

            for (int i = 0; i < GridView1.Rows.Count; i++)
            {
                CheckBox chkUpdate = (CheckBox)
                   GridView1.Rows[i].Cells[0].FindControl("chkSelect");
                if (chkUpdate != null)
                {
                    if (chkUpdate.Checked)
                    {

                        string strID = GridView1.Rows[i].Cells[1].Text;
                        string strPRSL = ((TextBox)
                            GridView1.Rows[i].FindControl("txtPRSL")).Text;

                        string strQuantity = ((TextBox)
                            GridView1.Rows[i].FindControl("txtQuantity")).Text;

                        string strPrice = ((TextBox)
                            GridView1.Rows[i].FindControl("txtPrice")).Text;

                        string strUnit = ((TextBox)
                            GridView1.Rows[i].FindControl("txtUnit")).Text;


                        string strUpdate =
                            "Update product set PRSL = '" + strPRSL + "',Quantity = '" + strQuantity + "',Price = '" + strPrice + "',Unit = '" + strUnit + "' WHERE ID ='" + strID + "'";

                        strSql.Append(strUpdate);
                    }
                }
            }
            try
            {
                cmd.CommandType = CommandType.Text;
                cmd.CommandText = strSql.ToString();
                cmd.Connection = con;
                con.Open();
                cmd.ExecuteNonQuery();
            }
            catch (SqlException ex)
            {
                string errorMsg = "Error in Updation";
                errorMsg += ex.Message;
                throw new Exception(errorMsg);
            }
            finally
            {
                con.Close();
            }
           
        }
      
        protected void chkSelect_CheckedChanged
                            (object sender, EventArgs e)
        {
            CheckBox chkTest = (CheckBox)sender;
            GridViewRow grdRow = (GridViewRow)chkTest.NamingContainer;
            TextBox txtPRSL = (TextBox)grdRow.FindControl
                                                ("txtPRSL");
            TextBox txtQuantity = (TextBox)grdRow.FindControl
                                              ("txtQuantity");

            TextBox txtPrice = (TextBox)grdRow.FindControl
                                              ("txtPrice");

            TextBox txtUnit = (TextBox)grdRow.FindControl
                                              ("txtUnit");

            if (chkTest.Checked)
            {
             
                txtQuantity.ReadOnly = false;
                txtQuantity.ForeColor = System.Drawing.Color.Red;
            }
            else
            {
               
                txtQuantity.ReadOnly = true;
                txtQuantity.ForeColor = System.Drawing.Color.Green;
            }
        }
    }
}