public DataTable LayTatCaPKKCL()
        {
            string        sql = "SELECT * FROM PHIEUKKCL";
            SqlConnection con = dc.getConnect();

            da = new SqlDataAdapter(sql, con);
            con.Open();
            DataTable dt = new DataTable();

            da.Fill(dt);
            con.Close();
            return(dt);
        }
        public DataTable getAllCHITIET_PHIEUXUAT()
        {
            string sql = "SELECT * FROM CHITIET_PHIEUXUAT";

            SqlConnection con = dc.getConnect();

            da = new SqlDataAdapter(sql, con);

            con.Open();

            DataTable dt = new DataTable();

            da.Fill(dt);

            con.Close();

            return(dt);
        }