*LOOP AT itab result [cond] GROUP BY key ( key1 = dobj1 key2 = dobj2 …

 *      [gs = GROUP SIZE] [gi = GROUP INDEX] )

 *      [ASCENDING|DESCENDING [AS TEXT]]

 *      [WITHOUT MEMBERS]

 *      [{INTO group}|{ASSIGNING <group>}]

 *      …

 *      [LOOP AT GROUP group|<group>

 *      …

 *      ENDLOOP.]

 *      …

 *ENDLOOP.

 *

 *… REDUCE type(

 *INIT result = start_value

 *           …

 *FOR for_exp1

 *FOR for_exp2

 *…

 *NEXT …

 *           result = iterated_value

 *… )

 "首先创建一个内表

 TYPES:BEGIN OF ty_data,

         id       TYPE i, "人员ID

         name     TYPE char10, "人员名称

         country  TYPE char10, "国家

         language TYPE char2, "语言

         age      TYPE i,

       END OF ty_data,

       ty_t_data TYPE STANDARD TABLE OF ty_data WITH EMPTY KEY.

 "数据

 DATA(gt_data) = VALUE ty_t_data(

 ( id =  name = 'Jerry' country = 'China' language = 'ZH' age =  )

 ( id =  name = 'Jack' country = 'China' language = 'ZH' age =  )

 ( id =  name = 'Nick' country = 'Korea' language = 'EN' age =  )

 ( id =  name = 'Rossi' country = 'Korea' language = 'EN' age =  )

 ( id =  name = 'Randy' country = 'Korea' language = 'EN' age =  )

 ( id =  name = 'Tab' country = 'China' language = 'ZH' age =  )

 ( id =  name = 'Lily' country = 'Korea' language = 'EN' age =  )

 ( id =  name = 'Lucy' country = 'China' language = 'EN' age =  )

 ( id =  name = 'Zera' country = 'China' language = 'EN' age =  )

 ( id =  name = 'Grace' country = 'China' language = 'EN' age =  )

 )

 .

 "REDUCE

 "1计算年龄最大

 DATA(lv_age_max_zh) = REDUCE i( INIT x =  FOR lw_data IN gt_data

                       WHERE ( language = 'ZH' ) NEXT x = nmax( val1 = x

                                                                val2 = lw_data-age )

                                                                ) .

 WRITE:/ |说中文的人中年龄最大的是：{ lv_age_max_zh  } |.

 "2.输出的reduce

 TYPES:outref TYPE REF TO if_demo_output.

 DATA(output) = REDUCE outref( INIT out = cl_demo_output=>new( )

                               text = 'Count up：'

                               FOR n =  UNTIL n >

                               NEXT out = out->write( text )

                               text = | { n } | ).

 output->display( ).

 "分组循环

 "1.ls_data这个工作区里面是没有内容的

 "2.<group>里面只有size index 和分组参数

 LOOP AT gt_data INTO DATA(ls_data) GROUP BY ( country = ls_data-country language = ls_data-language

   size = GROUP SIZE index = GROUP INDEX ) ASCENDING ASSIGNING FIELD-SYMBOL(<group>).

   WRITE:/ |Group:{ <group>-index } Country :{ <group>-country } language : { <group>-language }| &

   | Number lines :{ <group>-size } |.

   "3.按照<group>中的分组参数循环 GT_data中的数据

   LOOP AT GROUP <group> ASSIGNING FIELD-SYMBOL(<ls_member>).

     WRITE:/ | Name:{ <ls_member>-name } |.

   ENDLOOP.

   DATA(lv_age_max) = REDUCE i( INIT max =  FOR lw_member IN GROUP <group>

                              NEXT max = nmax( val1 = max val2 = lw_member-age ) ).

   DATA(lv_age_min) = REDUCE i( INIT min =  FOR lw_member IN GROUP <group>

                                NEXT min = nmin( val1 = min val2 = lw_member-age ) ).

   DATA(lv_age_sum) = REDUCE i( INIT sum =  FOR lw_member IN GROUP <group>

                                NEXT sum = sum + lw_member-age ).

   DATA(lv_age_avg) = lv_age_sum / <group>-size.

   WRITE:/ | 该组最大年龄，最小年龄和平均年龄分别为:{ lv_age_max } { lv_age_min } { lv_age_avg } |.

 ENDLOOP.