data:ls_sort type abap_sortorder.
data:lt_sort type abap_sortorder_tab.
ls_sort-name = 'WERKS'.
append ls_sort to lt_sort.
ls_sort-name = 'MATKL'.
append ls_sort to lt_sort.
ls_sort-name = 'MATNR'.
append ls_sort to lt_sort.
sort <dyn_table> by (lt_sort).