WORKING WITH DATA TABLE

.CS
   public DataTable CreateDataTable()
        {
            DataTable myDataTable = new DataTable();

            DataColumn myDataColumn;

            DataColumn auto = new DataColumn("AutoID", typeof(System.Int32));
            myDataTable.Columns.Add(auto);
            auto.AutoIncrement = true;
            auto.AutoIncrementSeed = 1;
            auto.ReadOnly = true;
            auto.Unique = true;

            DataColumn[] keys = new DataColumn[1];
            keys[0] = auto;
            myDataTable.PrimaryKey = keys;


            myDataColumn = new DataColumn();
            myDataColumn.DataType = Type.GetType("System.String");
            myDataColumn.ColumnName = "Date";
            myDataTable.Columns.Add(myDataColumn);

            myDataColumn = new DataColumn();
            myDataColumn.DataType = Type.GetType("System.String");
            myDataColumn.ColumnName = "Name Of Supply";
            myDataTable.Columns.Add(myDataColumn);

            myDataColumn = new DataColumn();
            myDataColumn.DataType = Type.GetType("System.String");
            myDataColumn.ColumnName = "Code Of Supply";
            myDataTable.Columns.Add(myDataColumn);

            myDataColumn = new DataColumn();
            myDataColumn.DataType = Type.GetType("System.String");
            myDataColumn.ColumnName = "DeliveryDate";
            myDataTable.Columns.Add(myDataColumn);


            myDataColumn = new DataColumn();
            myDataColumn.DataType = Type.GetType("System.String");
            myDataColumn.ColumnName = "Remark";
            myDataTable.Columns.Add(myDataColumn);


            myDataColumn = new DataColumn();
            myDataColumn.DataType = Type.GetType("System.String");
            myDataColumn.ColumnName = "ItemName";
            myDataTable.Columns.Add(myDataColumn);

            myDataColumn = new DataColumn();
            myDataColumn.DataType = Type.GetType("System.String");
            myDataColumn.ColumnName = "ItemCode";
            myDataTable.Columns.Add(myDataColumn);

            myDataColumn = new DataColumn();
            myDataColumn.DataType = Type.GetType("System.String");
            myDataColumn.ColumnName = "ReqQty";
            myDataTable.Columns.Add(myDataColumn);
            return myDataTable;


        }
        public void AddDataToTable(string Date, string DeliveryDate, string Remark, string ItemName, string ItemCode, string ReqQty, DataTable myTable)
        {
            DataRow row;
            row = myTable.NewRow();
            row["Date"] = Date;
            row["DeliveryDate"] = DeliveryDate;
            row["Remark"] = Remark;
            row["ItemName"] = ItemName;
            row["ItemCode"] = ItemCode;
            row["ReqQty"] = ReqQty;
            myTable.Rows.Add(row);
        }
.ASPX
     if (!Page.IsPostBack)
        {        
 
            DataTable myDt = new DataTable();
            myDt = objrequest.CreateDataTable();
            Session["myDatatable"] = myDt;
            GridView1.DataSource = ((DataTable)Session["myDatatable"]).DefaultView;
            GridView1.DataBind();
     
        }
    public void fiidataingrid1()
    {
            objrequest.AddDataToTable(this.txtDate.Text, this.txtDD.Text, this.txtRemarkes.Text, ddliname.SelectedItem.Text, this.ddliname.SelectedItem.Value, this.txtReqQuantity.Text, (DataTable)Session["myDatatable"]);
    
    }

    public void fiidataingrid()
    {
        if (Session["myDatatable"] != null)
        {
            DataTable dt = (DataTable)Session["myDatatable"];
            if ((dt != null) && (dt.Rows.Count > 0))
            {


                GridView1.Visible = true;
                GridView1.DataSource = ((DataTable)Session["myDatatable"]).DefaultView;
                GridView1.DataBind();
            }
            else
            {
                GridView1.Visible = false;
            }
        }
    }


EDIT/UPDATE/DELETE/DATABOUND
    protected void GridView1_RowCommand(object sender, GridViewCommandEventArgs e)
    {



    }
    protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
    {
        GridView1.EditIndex = -1;
        fiidataingrid();

    }
    protected void GridView1_RowDeleting(object sender, GridViewDeleteEventArgs e)
    {
        DataTable mydt = (DataTable)Session["myDatatable"];

        DataRow dr = mydt.Rows[e.RowIndex];

        mydt.Rows.Remove(dr);



        GridView1.EditIndex = -1;


        if (mydt.Rows.Count > 0)
        {

            fiidataingrid();
        }
        else
        {
            pnlFixed.Enabled = true;
            btnSave.Enabled = false;
            fiidataingrid();

        }




    }
    protected void GridView1_RowDeleted(object sender, GridViewDeletedEventArgs e)
    {

    }
    protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
    {
        GridView1.EditIndex = e.NewEditIndex;
        fiidataingrid();

    }
    protected void GridView1_RowUpdated(object sender, GridViewUpdatedEventArgs e)
    {

    }
    protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
    {

        TextBox txt4 = (TextBox)GridView1.Rows[e.RowIndex].FindControl("txtrqty1");
        DropDownList dd1 = (DropDownList)GridView1.Rows[e.RowIndex].FindControl("Ddliname");
        // DropDownList dd1 = (DropDownList)GridView1.Rows[e.RowIndex].FindControl("Ddliname");

        string newtxt4 = txt4.Text.ToString();
        string newtxt5 = dd1.SelectedValue.ToString();
        string newtxt6 = dd1.SelectedItem.ToString();

        DataTable dt = (DataTable)Session["myDatatable"];
        DataRow dr = dt.Rows[e.RowIndex];



        dr["ReqQty"] = newtxt4;
        dr["ItemName"] = newtxt6;
        dr["ITEMCODE"] = newtxt5;
        dr.AcceptChanges();
        Session["myDatatable"] = dt;

        GridView1.EditIndex = -1;
        fiidataingrid();




    }
    protected void GridView1_SelectedIndexChanged(object sender, EventArgs e)
    {

    }
    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {

        if (e.Row.RowType == DataControlRowType.DataRow)
        {
            if ((e.Row.RowState & DataControlRowState.Edit) > 0)
            {
                Label lableTemp = (Label)e.Row.FindControl("lblsetitem");
                DropDownList ddlTemp = (DropDownList)e.Row.FindControl("Ddliname");
                DataSet ds = RealStateClass.Requestpage.fillitem();
                ddlTemp.DataSource = ds;
                ddlTemp.DataTextField = "itemNAME";
                ddlTemp.DataValueField = "ITEMCODE";
                ddlTemp.Text = lableTemp.Text;
                ddlTemp.DataBind();
            }
        }
    }