紧急求救：ABAP ON CHANGE OF 的语法

xiebinren · 发表于 2008-6-23 13:37

原帖由 jltt 于 2008-6-23 11:57 发表
当用户提交时
判断，当前该字段中的值与初始值之间是否相同
如果不同，则触发该事件。

谢谢老大，那我理解正确了

meixuepeng · 发表于 2008-7-2 20:54

复习一下知识

vincibb · 发表于 2010-3-28 22:29

ON CHANGE OF

Syntax
ON CHANGE OF dobj [OR dobj1 [OR dobj2] ... ].
  statement_block
ENDON.

Effect:
The statements ON CHANGE OF and ENDON, which are forbidden in classes, define a control structure that can contain a statement block statement_block. After ON CHANGE OF, any number of data objects dobj1, dobj2... of any data type can be added, linked by OR.

The first time a statement ON CHANGE OF is executed, the statement block is executed if at least one of the specified data objects is not initial. The statement block is executed for each additional execution of the same statement ON CHANGE OF, if the content of one of the specified data objects has been changed since the last time the statement ON CHANGE OF was executed.

For each time the statement ON CHANGE OF is executed, the content of all the specified data objects is saved as an auxiliary variable internally in the global system. The auxiliary variable is linked to this statement and cannot be accessed in the program. The auxiliary variables and their contents are retained longer than the lifetime of procedures. An auxiliary variable of this type can only be initialized if its statement ON CHANGE OF is executed while the associated data object is initial.

Note:
This control structure, which is forbidden in classes, is particularly prone to errors and should be replaced by branches with explicitly declared auxiliary variables.

Example:
In a SELECT loop, a statement block should only be executed if the content of the column CARRID has changed.

DATA spfli_wa TYPE spfli.
SELECT *
   FROM spfli
   INTO spfli_wa
   ORDER BY carrid.
  ...
  ON CHANGE OF spfli_wa-carrid.
...
  ENDON.
  ...
ENDSELECT.

The following section of a program shows how the ON control structure can be replaced by an IF control structure with an explicit auxiliary variable carrid_buffer.

DATA carrid_buffer TYPE spfli-carrid.
CLEAR carrid_buffer.
SELECT *
   FROM spfli
   INTO spfli_wa
   ORDER BY carrid.
  ...
  IF spfli_wa-carrid <> carrid_buffer.
carrid_buffer = spfli_wa-carrid.
...
  ENDIF.
  ...
ENDSELECT.

////////////////////////////////////////////////
ON CHANGE OF dobj [OR dobj1 [OR dobj2] ... ].
  statement_block
ENDON

意思是说 dobj 或 dobj1 或 dobj2 发生变化时候，执行statement_block