at first 用於第一行;
at last 用於最後一行;
at new field 當field字段前面或者他本身的值與上一條記錄的值不同時,才執行at endat裏面的代碼;
at end field 與at new相似,這裏只是與下一條記錄的值進行比較。
實例代碼:
###代碼塊
```
ABAP
DATA: t1(4) TYPE c, t2 TYPE i.
FIELD-GROUPS: header.
INSERT t2 t1 INTO header.
t1 ='AABB'. t2 = 1. EXTRACT header.
t1 ='BBCC'. t2 = 2. EXTRACT header.
t1 ='AAAA'. t2 = 2. EXTRACT header.
t1 ='AABB'. t2 = 1. EXTRACT header.
t1 ='BBBB'. t2 = 2. EXTRACT header.
t1 ='BBCC'. t2 = 2. EXTRACT header.
t1 ='AAAA'. t2 = 1. EXTRACT header.
t1 ='BBBB'. t2 = 1. EXTRACT header.
t1 ='AAAA'. t2 = 3. EXTRACT header.
t1 ='AABB'. t2 = 1. EXTRACT header.
SORT BY t1 t2.
LOOP.
AT FIRST.
WRITE 'Start of LOOP'.
ULINE.
ENDAT.
AT NEW t1.
WRITE / ' New T1:'.
ENDAT.
AT NEW t2.
WRITE / ' New T2:'.
ENDAT.
WRITE: /14 t1, t2.
AT END OF t2.
WRITE / 'End of T2'.
ENDAT.
AT END OF t1.
WRITE / 'End of T1'.
ENDAT.
AT LAST.
ULINE.
ENDAT.
ENDLOOP.
結果如下: