public DataTable search(string name)
{
string str = "select a.masach, a.tensach, ls.maloaisach, a.soluong, a.make from sach as a, loaisach as ls where ls.tenloaisach = N'" + name + "' and ls.maloaisach = a.maloaisach";
DBMain dB = new DBMain();
DataTable table = dB.ExecuteQuery(str);
return(table);
}