data:it_tab type table of tab(���ݿ��),
    wa_tab like line of it_tab.

    ����ɾ����
    delete tab from wa_tab.
    delete tab from table it_tab.

    ɾ���ڱ�����:
    delte from it_tab where abc(�ֶ�).

    ȥ��:
    DELETE ADJACENT DUPLICATES FROM it_tab COMPARING all files.