METHOD combine_seltabs.
    DATA:
      ls_seltab TYPE ts_named_seltable,
      lr_seltab TYPE REF TO cl_shdb_seltab,
      lv_sep    TYPE string.
    FIELD-SYMBOLS
      <fs_seltab> TYPE table.

    IF iv_client_field IS NOT INITIAL.
      rv_where = |{ iv_client_field } = '{ sy-mandt }'|.
      lv_sep = ` AND `.
    ENDIF.

    LOOP AT it_named_seltabs INTO ls_seltab.
      ASSIGN ls_seltab-dref->* TO <fs_seltab>.
      IF <fs_seltab> IS NOT INITIAL.
        lr_seltab = cl_shdb_seltab=>new( <fs_seltab> ).
        rv_where = |{ rv_where }{ lv_sep }({ lr_seltab->sql_where_condition( ls_seltab-name ) })|.
        lv_sep = ' AND '.
      ENDIF.
    ENDLOOP.

  ENDMETHOD.