sap-abap-at first at last at new at end

AT FIRST: 循环内表的第一行时触发执行的代码。只执行一次。

AT LAST: 循环内表的最后一行数据时执行代码。即在LOOP里把该执行的都执行完了才执行它。

AT NEW F1: 如果字段F及F的左则全部字段的数据，与上一行数据不一致，则执行代码。 先执行一行，开始判断，如果第二行和第一行值不一样，执行 AT END OF F1;

如果值一样，继续循环AT NEW F1.

AT END OF F1: 如果字段F及F的左则全部字段的数据，与下一行数据不一致时，则执行代码。

AT....End AT语句块内：循环每一行数据时都执行.

REPORT ZKAVEN_002.

DATA: BEGIN OF gs_i,
  n1 TYPE i,
  n2 TYPE i,
  c1 TYPE c,
  i TYPE i,
  i_summary TYPE i,
END OF gs_i.
DATA: gs_i2 LIKE gs_i.
DATA: gs_i3 LIKE gs_i.

DATA: gt_i LIKE STANDARD TABLE OF gs_i.
DATA: gt_i2 LIKE STANDARD TABLE OF gs_i.
DATA: gt_i3 LIKE STANDARD TABLE OF gs_i.

gs_i-n1 = 1.
gs_i-n2 = 1.
gs_i-c1 = 'a'.
gs_i-i = 1.
APPEND  gs_i TO gt_i.

gs_i-n1 = 1.
gs_i-n2 = 2.
gs_i-c1 = 'a'.
gs_i-i = 8.
APPEND gs_i TO gt_i.

gs_i-n1 = 2.
gs_i-n2 = 1.
gs_i-c1 = 'a'.
gs_i-i = 3.
APPEND gs_i TO gt_i.

gs_i-n1 = 2.
gs_i-n2 = 2.
gs_i-c1 = 'a'.
gs_i-i = 4.
APPEND gs_i TO gt_i.

*MOVE-CORRESPONDING


CLEAR gs_i.
DATA: g_tabix LIKE sy-tabix.
*使用at first和at last使用时，所有的非数字字段值变为*
*at new 和 at end 使用时，new后面的非数值字段值变为 *，
*at new 和 at end 使用sum均是计算区间内的数字字段内容之和
*通过READ TABLE gt_i INTO gs_i INDEX g_tabix. 解决使用时出现的*的问题。

LOOP AT gt_i INTO gs_i.
  g_tabix = sy-tabix.

  WRITE: /, 'original',gs_i-n1, gs_i-n2,gs_i-c1, gs_i-i, gs_i-i_summary.

  AT FIRST.
   WRITE: /, 'first',gs_i-n1, gs_i-n2,gs_i-c1, gs_i-i, gs_i-i_summary.
  ENDAT.

  AT NEW n1.
    READ TABLE gt_i INTO gs_i INDEX g_tabix.    "通过读取行内表至工作区，

    MOVE gs_i TO gs_i2.            "不需要汇总的字段，赋值
    SUM.
    gs_i2-i_summary = gs_i-i.               "需要汇总的字段
    APPEND gs_i2 TO gt_i2.
  ENDAT.

  AT END OF n1.
    READ TABLE gt_i INTO gs_i INDEX g_tabix.    "通过读取行内表至工作区，

    MOVE gs_i TO gs_i3.            "不需要汇总的字段，赋值
    SUM.
    gs_i3-i_summary = gs_i-i.               "需要汇总的字段
    APPEND gs_i3 TO gt_i3.
  ENDAT.


  AT LAST.
    WRITE: /, 'last' ,gs_i-n1, gs_i-n2,gs_i-c1, gs_i-i, gs_i-i_summary.
  ENDAT.


ENDLOOP.


CLEAR gs_i.
LOOP AT gt_i2 INTO gs_i.
  WRITE: /, 'gt_i2', gs_i-n1, gs_i-n2,gs_i-c1, gs_i-i, gs_i-i_summary.
ENDLOOP.
LOOP AT gt_i3 INTO gs_i.
  WRITE: /, 'gt_i3 ', gs_i-n1, gs_i-n2,gs_i-c1, gs_i-i, gs_i-i_summary.
ENDLOOP.