I have error in updating records in database sql server - asp.net

Question

I have a problem : I have page for insert data into database , and the same page for update data based on query string for each item , the problem when i update the fields from textbox(s) , the same data is returned to update: the same data updated in database from textbox in page_load !!
In Page_Load
con.Open();
//For edit items
if (Request.QueryString["id"] != null)
{
Page.Title = "Edit Items";
DataTable dt = Get_Items(Request.QueryString["id"].ToString());
txt_item_name.Text = dt.Rows[0]["name"].ToString();
txt_end_date.Text = dt.Rows[0]["endDate"].ToString();
Btn_addItem.Text = "Edit item";
}
protected void Btn_addItem_Click(object sender, EventArgs e)
{
if (Btn_addItem.Text.Equals("Add Item"))
{
SqlCommand cmd = new SqlCommand("addedit", con);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("#item_id", "-1");
cmd.Parameters.AddWithValue("#name", txt_item_name.Text);
cmd.Parameters.AddWithValue("#endDate", txt_end_date.Text);
con.Open();
cmd.ExecuteNonQuery();
lbl_msg.Text = "Item added....";
con.Close();
}
else
{
SqlCommand cmd = new SqlCommand("addedit", con);
cmd.CommandType = CommandType.StoredProcedure;
cmd.Parameters.AddWithValue("#item_id", Request.QueryString["id"]);
cmd.Parameters.AddWithValue("#name", txt_item_name.Text);
cmd.Parameters.AddWithValue("#endDate", txt_end_date.Text);
con.Open();
cmd.ExecuteNonQuery();
lbl_msg.Text = "Item edited....";
con.Close();
}
}

Answer 1

If I understand your question correctly "You are not able to update the DB with the new value you enter in the textboxes. Its updating the DB with the old value again".
You need to check for !IsPostback in your Page_Load as the code for binding the textboxes from DB will be called before Btn_addItem_Click during postback and it will set the value of textboxes back to the old value from DB. See below updated code:
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
con.Open();
//For edit items
if (Request.QueryString["id"] != null)
{
Page.Title = "Edit Items";
DataTable dt = Get_Items(Request.QueryString["id"].ToString());
txt_item_name.Text = dt.Rows[0]["name"].ToString();
txt_end_date.Text = dt.Rows[0]["endDate"].ToString();
Btn_addItem.Text = "Edit item";
}
}
}
Hope it helps.