for

where

gt_value_tab2 = VALUE #( FOR wa IN gt_value_tab WHERE ( msgnr < 100 ) ( wa )  ).

from

  gt_value_tab4 = VALUE #(
  BASE gt_value_tab2 "在基础之上添加其他数据
  FOR wa IN gt_value_tab FROM 2 TO 3 ( wa )  ).

next

for **  in   next
       bookings = REDUCE #( "reduce语法创建结果即用于计算结果的语句，其中可写计算exp
       INIT s = 0
       FOR flight IN GROUP <carrier>
*       INDEX INTO i   "  一帮用来计算总数
      NEXT s = s + flight-seatsocc ) ) ).

group 分组计算总数

  LOOP AT lt_sflight INTO DATA(ls_sflight)
             GROUP BY ls_sflight-carrid
              ASCENDING
              ASSIGNING FIELD-SYMBOL(<carrier>).

    "按组汇总数据
    lt_list = VALUE tt_list(
            BASE lt_list ( carrier = <carrier>
          bookings = REDUCE #( "reduce语法创建结果即用于计算结果的语句，其中可写计算exp
           INIT s = 0
           FOR flight IN GROUP <carrier>
*           INDEX INTO i
          NEXT s = s + flight-seatsocc ) ) ).

    "按组明细数据
    cl_demo_output=>write( '按组明细: ' ).
    cl_demo_output=>write( <carrier> ).
    lt_list2 = VALUE tt_list(
       FOR <fs> IN GROUP <carrier>
          ( carrier = <carrier>
           bookings = <fs>-seatsocc ) ) .

    cl_demo_output=>write( lt_list2 ).

until

   cl_demo_output=>display( 
    REDUCE i( INIT s = 0 
            FOR  i = 1 UNTIL i > 10 
            NEXT s = s + i ) ).