syntax error: select * from sanpham where cohang = '1' and idDM or idDM in (select idDM from danhmuc where cap1 = ) or idDM in (select idDM from danhmuc where dmCha = ) or idDM in (select idDM from danhmuc where dmCha in (select idDM from danhmuc where cap1 = )) order by khuyenmai ASC