asp.net gridview edit button doesn't update - asp.net

Question

When I enter new data and press update button it saves the old data (data that I want it to update).
public void fill()
{
SqlCommand cmd = new SqlCommand("select * from school ",con );
con.Open();
SqlDataReader rd = cmd.ExecuteReader();
GridView1.DataSource = rd;
GridView1.DataBind();
con.Close();
}
protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
{
fill();
}
protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
{
int id = int.Parse(((TextBox)GridView1.Rows[e.RowIndex].Cells[1].Controls[0]).Text);
string stu =((TextBox)GridView1.Rows[e.RowIndex].Cells[2].Controls[0]).Text;
int age = int.Parse(((TextBox)GridView1.Rows[e.RowIndex].Cells[3].Controls[0]).Text);
SqlCommand cmd = new SqlCommand("UPDATE school SET stu_name=#stu_name,age=#age where id=#id ", con);
cmd.Parameters.Add(new SqlParameter("#id", id));
cmd.Parameters.Add(new SqlParameter("#stu_name", stu));
cmd.Parameters.Add(new SqlParameter ("#age",age));
con.Open();
cmd.ExecuteNonQuery();
con.Close();
GridView1.EditIndex = -1;
fill();
}
he problem that the values that assigned to name,age are the existing values in the database not the new values which I entered in the runtime
any one can help me??
thanks in advance

Answer 1

You are repopulating the grid every time you edit it.
Call fill(); on grid init instead.

Answer 2

Here's some info on the Life Cycle of a web form. I think all you need is to wrap your fill(); in an if statement. Because page_load happens before your event handler, you reload from the db on top of the values that were entered.
if(!PostBack)
{
fill();
}