public void Load_cbo_TenNPP()
{
string strsel = "select * from NhaPhanPhoi";
DataTable dt = conn.getDataTable(strsel, "NhaPhanPhoi");
cbo_TenNPP.DataSource = dt;
cbo_TenNPP.DisplayMember = "TenNPP";
cbo_TenNPP.ValueMember = "MaNPP";
}