Unable to update the textbox values in the gridview[c# asp.net] - asp.net

Question

Getting old values in DataTable, I need new values which I updated. Please help me?
Update on button click
My code:
DataSet Ds = new DataSet();
string Query = "";
Query = "select Conv_0,Unit_0,Rate_0,Text_0,Barcode_0,Conv_1,Unit_1,Rate_1,Text_1,Barcode_1,Conv_2,Unit_2,Rate_2,Text_2,Barcode_2,Conv_3,Unit_3,Rate_3,Text_3,Barcode_3,Conv_4,Unit_4,Rate_4,Text_4,Barcode_4 from Prod_Unit where Code='" + a + "'";
Ds = SqlClass1.GetData_from_localhost(Query);
if (Ds.Tables[0].Rows.Count > 0)
{
dt.Columns.Clear();
dt.Rows.Clear();
dt.Columns.Add("NO");
dt.Columns.Add("UNITS");
dt.Columns.Add("CONVERSION");
dt.Columns.Add("BARCODE");
dt.Columns.Add("RATE 1");
dt.Columns.Add("RATE 2");
dt.Columns.Add("PRINT TEXT");
// dt.Rows.Add();
for (int i = 0; i < Ds.Tables[0].Columns.Count; i++)
{
if (i >= 0 && i <= 4)
{
dt.Rows.Add();
dt.Rows[i]["NO"] = i + 1;
string unit = Ds.Tables[0].Rows[0]["Unit_" + i + ""].ToString();
DataSet temp = SqlClass1.GetData_from_localhost("select Unit FROM Units where Code=" + unit + "");
if (temp.Tables[0].Rows.Count > 0)
{
dt.Rows[i]["UNITS"] = temp.Tables[0].Rows[0][0].ToString();
}
dt.Rows[i]["CONVERSION"] = Ds.Tables[0].Rows[0]["Conv_" + i + ""].ToString();
dt.Rows[i]["BARCODE"] = Ds.Tables[0].Rows[0]["Barcode_" + i + ""].ToString();
dt.Rows[i]["RATE 1"] = Ds.Tables[0].Rows[0]["Rate_" + i + ""].ToString();
dt.Rows[i]["RATE 2"] = Ds.Tables[0].Rows[0]["Rate_" + i + ""].ToString();
dt.Rows[i]["PRINT TEXT"] = Ds.Tables[0].Rows[0]["Text_" + i + ""].ToString();
}
}
if (i == 0)
{
// ViewState["CurrentTable"] = dt;
GridView1.DataSource = dt;
GridView1.DataBind();
// SetPreviousData();
}
}
ViewState["CurrentTable"] = dt;
GridView1.DataSource = dt;
GridView1.DataBind();
SetPreviousData();// function to get previous data in
textbox
This is my binding function that I call in postback. How can I get updated values in ViewState["CurrentTable"] = dt;

Answer 1

on Update Button
DataTable dt = new DataTable();
DataRow dr;
dt.Columns.Add("NO");
dt.Columns.Add("UNITS");
dt.Columns.Add("CONVERSION");
dt.Columns.Add("BARCODE");
dt.Columns.Add("RATE 1");
dt.Columns.Add("RATE 2");
dt.Columns.Add("PRINT TEXT");
dr = dt.NewRow();
dr["NO"] = 1;
dr["UNITS"] = string.Empty;
dr["CONVERSION"] = string.Empty;
dr["BARCODE"] = string.Empty;
dr["RATE 1"] = string.Empty;
dr["RATE 2"] = string.Empty;
dr["PRINT TEXT"] = string.Empty;
dt.Rows.Add(dr);
int rowIndex = 0;
for (int i = 0; i < GridView1.Rows.Count; i ++)
{
if (GridView1.Rows[rowIndex].RowType == DataControlRowType.DataRow)
{
DropDownList box1 = (DropDownList)GridView1.Rows[rowIndex].Cells[1].FindControl("DropDownList1");
TextBox box2 = (TextBox)GridView1.Rows[rowIndex].Cells[2].FindControl("TextBox2");
TextBox box3 = (TextBox)GridView1.Rows[rowIndex].Cells[3].FindControl("TextBox3");
TextBox box4 = (TextBox)GridView1.Rows[rowIndex].Cells[4].FindControl("TextBox4");
TextBox box5 = (TextBox)GridView1.Rows[rowIndex].Cells[5].FindControl("TextBox5");
TextBox box6 = (TextBox)GridView1.Rows[rowIndex].Cells[6].FindControl("TextBox6");
dt.Rows[i]["NO"] = i + 1;
dt.Rows[i]["Units"] = box1.Text;
dt.Rows[i]["Conversion"] = box2.Text;
dt.Rows[i]["Barcode"] = box3.Text;
dt.Rows[i]["Rate 1"] = box4.Text;
dt.Rows[i]["Rate 2"] = box5.Text;
dt.Rows[i]["Print Text"] = box6.Text;
dt.Rows.Add();
rowIndex++;
}
}
ViewState["CurrentTable"] = dt;
Save();//function for save
}