ABAP FILTER对内表数据进行筛选

ABAP提供FILTER语法对内表数据进行筛选，
测试代码如下：

    SELECT *
      FROM marc
      INTO TABLE @lt_marc
      UP TO 1000 ROWS.

    IF value ='X'.

      DATA(table1) =
        FILTER #( lt_marc USING KEY group_marc               "按关键字筛选
                    WHERE matnr   = CONV #( to_upper( matnr ) ) AND
                          werks = CONV #( to_upper( werks ) ) ).

      cl_demo_output=>display( table1 ).

    ELSE.

      DATA(table2) =
        FILTER #( lt_marc EXCEPT USING KEY group_marc       "按关键字排除
                    WHERE matnr   = CONV #( to_upper( matnr ) ) AND
                          werks = CONV #( to_upper( werks ) ) ).

      cl_demo_output=>display( table2 ).

1.勾选筛选USING KEY，满足屏幕条件的数据从内表中被筛选出：
如下代码：

      DATA(table1) =
        FILTER #( lt_marc USING KEY group_marc               "按关键字筛选
                    WHERE matnr   = CONV #( to_upper( matnr ) ) AND
                          werks = CONV #( to_upper( werks ) ) ).

2.取消筛选EXCEPT USING KEY，则筛选内表中不满足条件的数据全都展示出来：

如下代码：

      DATA(table2) =
        FILTER #( lt_marc EXCEPT USING KEY group_marc       "按关键字排除
                    WHERE matnr   = CONV #( to_upper( matnr ) ) AND
                          werks = CONV #( to_upper( werks ) ) ).