how to bind data that we just entered into gridview

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False"
DataSourceID="SqlDataSource2">
<columns>
<asp:BoundField DataField="nama_barang" HeaderText="nama_barang"
SortExpression="nama_barang" />
<asp:BoundField DataField="bilangan" HeaderText="bilangan"
SortExpression="bilangan" />
<asp:BoundField DataField="stock_last" HeaderText="stock_last"
SortExpression="stock_last" />


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<asp:SqlDataSource ID="SqlDataSource2" runat="server"
ConnectionString="<%$ ConnectionStrings:connectionString %>"
SelectCommand="SELECT [nama_barang], [bilangan], [stock_last] FROM [approval]">



protected void Button3_Click(object sender, EventArgs e)
{
SqlConnection cn0 = new SqlConnection(connectionString);
cn0.Open();


int last = int.Parse(Label3.Text);
int req = int.Parse(TextBox7.Text);
int kuantiti = last - req;


string s = "update stocks set stock_left = @stock_left where id_ = '" + ddl1.SelectedIndex + "'";
SqlCommand cd = new SqlCommand(s, cn0);

cd.Parameters.Add("@stock_left", SqlDbType.Int).Value = kuantiti;


string l = "insert into approval (item, quantity, stock_last) values (@item, @quantity, @stock_last)";
SqlCommand c = new SqlCommand(l, cn0);
c.Parameters.Add("@item", SqlDbType.VarChar).Value = ddl1.SelectedItem.Text.Trim();
c.Parameters.Add("@quantity", SqlDbType.Int).Value = TextBox7.Text.Trim();
c.Parameters.Add("@stock_last", SqlDbType.Int).Value = kuantiti;

cd.ExecuteNonQuery();
c.ExecuteNonQuery();
}

protected void ddl1_SelectedIndexChanged(object sender, EventArgs e)
{

SqlConnection cn = new SqlConnection(connectionString);
cn.Open();
string sql = "select stock_left from stocks where nama_barang = '"+ ddl1.SelectedItem.Text +"' ";
SqlCommand c = new SqlCommand(sql, cn);
SqlDataReader dr = c.ExecuteReader();
dr.Read();

if (Convert.ToInt32(dr[0]) > 0)
{
Label3.Text = Convert.ToString(dr[0]);
}
else
{
Label3.Text = "No stock!";
Label3.ForeColor = System.Drawing.Color.Red;
}





}
protected void Button5_Click(object sender, EventArgs e)
{
GridView1.Visible = true;
}