参考程序：ZSCRN001
TYPE-POOLS:vrm.
DATA: name TYPE vrm_id.
DATA:num TYPE i. "内表判断字段长度的变量
TYPES: BEGIN OF wa ,
key(40),
text(80) TYPE c,
END OF wa.
DATA:gt LIKE t179t OCCURS 0 WITH HEADER LINE.
DATA:wa1 TYPE TABLE OF wa WITH HEADER LINE. "111
DATA:wa2 TYPE TABLE OF wa WITH HEADER LINE ."111222
DATA:wa3 TYPE TABLE OF wa WITH HEADER LINE. "111222333
DATA:itab LIKE t179t OCCURS 0 WITH HEADER LINE.
DATA: ps_t(15) TYPE c.
SELECTION-SCREEN BEGIN OF BLOCK t1 WITH FRAME TITLE title1.
SELECTION-SCREEN BEGIN OF LINE.
SELECTION-SCREEN COMMENT 1(31) text-003.
PARAMETERS: pl1 LIKE ps_t AS LISTBOX VISIBLE LENGTH 15 USER-COMMAND p1 ."一级类
SELECTION-SCREEN END OF LINE.
SELECTION-SCREEN SKIP 1.
SELECTION-SCREEN BEGIN OF LINE.
SELECTION-SCREEN COMMENT 1(31) text-004.
PARAMETERS: pl2 LIKE ps_t AS LISTBOX VISIBLE LENGTH 15 USER-COMMAND p2."二级类
SELECTION-SCREEN END OF LINE.
SELECTION-SCREEN SKIP 1.
SELECTION-SCREEN BEGIN OF LINE.
SELECTION-SCREEN COMMENT 1(31) text-005.
PARAMETERS: pl3 LIKE ps_t AS LISTBOX VISIBLE LENGTH 15."三级类
SELECTION-SCREEN END OF LINE.
SELECTION-SCREEN SKIP 1.
SELECTION-SCREEN BEGIN OF LINE.
SELECTION-SCREEN PUSHBUTTON 1(11) btntxt USER-COMMAND btn1.
SELECTION-SCREEN COMMENT 12(20) text-006.
PARAMETERS:z_sn2 TYPE matnr.
SELECTION-SCREEN END OF LINE.
SELECTION-SCREEN END OF BLOCK t1.
INITIALIZATION.
btntxt = ‘从开始到现在‘.
AT SELECTION-SCREEN OUTPUT.
name = ‘PL1‘.
SELECT * FROM t179t INTO TABLE gt WHERE spras = 1 .
LOOP AT gt.
num = STRLEN( gt-prodh ).
IF num = 5.
wa1-text = gt-vtext.
wa1-key = gt-prodh.
APPEND: wa1.
ENDIF.
CLEAR: gt,num,wa1.
ENDLOOP.
CALL FUNCTION ‘VRM_SET_VALUES‘
EXPORTING
id = name
values = wa1[].
AT SELECTION-SCREEN.
CASE sy-ucomm.
WHEN ‘P1‘.
CLEAR: pl2,pl3. "清空2、3级下拉空默认值，当用户在选择屏幕上重新选择时需要清除
CLEAR:wa2,wa2[]. "清空2级下拉内表对应的值，当用户在选择屏幕上重新选择时需要清除
CLEAR num.
LOOP AT gt .
num = STRLEN( gt-prodh ).
IF num = 10 AND gt-prodh+0(5) = pl1.
wa2-text = gt-vtext.
wa2-key = gt-prodh.
APPEND: wa2.
ENDIF.
CLEAR:gt,num,wa2.
ENDLOOP.
CALL FUNCTION ‘VRM_SET_VALUES‘
EXPORTING
id = ‘PL2‘
values = wa2[].
CLEAR pl2.
WHEN ‘P2‘.
CLEAR pl3. "清空3级下拉空默认值，当用户在选择屏幕上重新选择时需要清除
CLEAR:wa3,wa3[]. "清空3级下拉内表对应的值，当用户在选择屏幕上重新选择时需要清除
CLEAR num.
LOOP AT gt .
num = STRLEN( gt-prodh ).
IF num = 18 AND gt-prodh+0(10) = pl2.
wa3-text = gt-vtext.
wa3-key = gt-prodh.
APPEND: wa3.
ENDIF.
CLEAR:gt,num,wa3.
ENDLOOP.
CALL FUNCTION ‘VRM_SET_VALUES‘
EXPORTING
id = ‘PL3‘
values = wa3[].
CLEAR pl3.
ENDCASE.
原文：https://www.cnblogs.com/jimi520/p/12125573.html