2019.12.05【ABAP随笔】 分组循环(LOOP AT Group) / REDUCE
ABAP 7.40新语法 LOOP AT Group 和 REDUCE
1 *LOOP AT itab result [cond] GROUP BY key ( key1 = dobj1 key2 = dobj2 … 2 * [gs = GROUP SIZE] [gi = GROUP INDEX] ) 3 * [ASCENDING|DESCENDING [AS TEXT]] 4 * [WITHOUT MEMBERS] 5 * [{INTO group}|{ASSIGNING <group>}] 6 * … 7 * [LOOP AT GROUP group|<group> 8 * … 9 * ENDLOOP.] 10 * … 11 *ENDLOOP. 12 * 13 *… REDUCE type( 14 *INIT result = start_value 15 * … 16 *FOR for_exp1 17 *FOR for_exp2 18 *… 19 *NEXT … 20 * result = iterated_value 21 *… ) 22 23 24 "首先创建一个内表 25 TYPES:BEGIN OF ty_data, 26 id TYPE i, "人员ID 27 name TYPE char10, "人员名称 28 country TYPE char10, "国家 29 language TYPE char2, "语言 30 age TYPE i, 31 END OF ty_data, 32 ty_t_data TYPE STANDARD TABLE OF ty_data WITH EMPTY KEY. 33 34 "数据 35 DATA(gt_data) = VALUE ty_t_data( 36 ( id = 1 name = 'Jerry' country = 'China' language = 'ZH' age = 18 ) 37 ( id = 2 name = 'Jack' country = 'China' language = 'ZH' age = 19 ) 38 ( id = 3 name = 'Nick' country = 'Korea' language = 'EN' age = 20 ) 39 ( id = 4 name = 'Rossi' country = 'Korea' language = 'EN' age = 25 ) 40 ( id = 5 name = 'Randy' country = 'Korea' language = 'EN' age = 23 ) 41 ( id = 6 name = 'Tab' country = 'China' language = 'ZH' age = 22 ) 42 ( id = 7 name = 'Lily' country = 'Korea' language = 'EN' age = 21 ) 43 ( id = 8 name = 'Lucy' country = 'China' language = 'EN' age = 24 ) 44 ( id = 9 name = 'Zera' country = 'China' language = 'EN' age = 28 ) 45 ( id = 10 name = 'Grace' country = 'China' language = 'EN' age = 19 ) 46 ) 47 . 48 49 "REDUCE 50 "1计算年龄最大 51 DATA(lv_age_max_zh) = REDUCE i( INIT x = 0 FOR lw_data IN gt_data 52 WHERE ( language = 'ZH' ) NEXT x = nmax( val1 = x 53 val2 = lw_data-age ) 54 ) . 55 WRITE:/ |说中文的人中年龄最大的是：{ lv_age_max_zh } |. 56 57 "2.输出的reduce 58 TYPES:outref TYPE REF TO if_demo_output. 59 DATA(output) = REDUCE outref( INIT out = cl_demo_output=>new( ) 60 text = 'Count up：' 61 FOR n = 1 UNTIL n > 11 62 NEXT out = out->write( text ) 63 text = | { n } | ). 64 output->display( ). 65 66 "分组循环 67 "1.ls_data这个工作区里面是没有内容的 68 "2.<group>里面只有size index 和分组参数 69 LOOP AT gt_data INTO DATA(ls_data) GROUP BY ( country = ls_data-country language = ls_data-language 70 size = GROUP SIZE index = GROUP INDEX ) ASCENDING ASSIGNING FIELD-SYMBOL(<group>). 71 72 WRITE:/ |Group:{ <group>-index } Country :{ <group>-country } language : { <group>-language }| & 73 | Number lines :{ <group>-size } |. 74 75 "3.按照<group>中的分组参数循环 GT_data中的数据 76 LOOP AT GROUP <group> ASSIGNING FIELD-SYMBOL(<ls_member>). 77 78 WRITE:/ | Name:{ <ls_member>-name } |. 79 80 ENDLOOP. 81 82 DATA(lv_age_max) = REDUCE i( INIT max = 0 FOR lw_member IN GROUP <group> 83 NEXT max = nmax( val1 = max val2 = lw_member-age ) ). 84 85 DATA(lv_age_min) = REDUCE i( INIT min = 100 FOR lw_member IN GROUP <group> 86 NEXT min = nmin( val1 = min val2 = lw_member-age ) ). 87 88 DATA(lv_age_sum) = REDUCE i( INIT sum = 0 FOR lw_member IN GROUP <group> 89 NEXT sum = sum + lw_member-age ). 90 DATA(lv_age_avg) = lv_age_sum / <group>-size. 91 92 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 } |. 93 ENDLOOP.
结果为:
个人感觉LOOP AT GROUP 和 REDUCE可以很好的代替 LOOP 中使用 AT END OF field 和 AT NEW field ( 这个是需要调整内表结构字段顺序的)。
平时用在分组求和，分组操作的时候还是很好用的。
-TAB 热爱技术 享受生活
