740新语法中,对标READ,提出了新的语法,如下:
## ** 1.1、根据字段值查找 **
"-----------------------------@斌将军-----------------------------"老语法READ TABLE lt_acd INTO ls_acd WITH KEY rbukrs = gs_acd-rbukrs.IF sy-subrc EQ 0.
ENDIF.
"新语法ls_acd = lt_acd[ rbukrs = gs_acd-rbukrs ]."-----------------------------@斌将军-----------------------------## ** 1.2、按索引查找 **
"-----------------------------@斌将军-----------------------------"老语法READ TABLE lt_acd INTO ls_acd INDEX 1.IF sy-subrc EQ 0.
ENDIF.
"新语法ls_acd = lt_acd[ 1 ]."-----------------------------@斌将军-----------------------------## ** 1.3、判断记录是否存在 **
"-----------------------------@斌将军-----------------------------"老语法READ TABLE lt_acd WITH KEY rbukrs = gs_acd-rbukrs TRANSPORTING NO FIELDS.IF sy-subrc EQ 0.
ENDIF.
"新语法IF LINE_EXISTS( lt_acd[ rbukrs = gs_acd-rbukrs ] ). ENDIF."-----------------------------@斌将军-----------------------------## ** 1.4、获取行索引 **
"-----------------------------@斌将军-----------------------------"老语法READ TABLE lt_acd WITH KEY rbukrs = gs_acd-rbukrs TRANSPORTING NO FIELDS.IF sy-subrc EQ 0.WRITE:SY-TABIX.ENDIF.
"新语法LV_INDEX = LINE_INDEX( lt_acd[ rbukrs = gs_acd-rbukrs ] )."-----------------------------@斌将军-----------------------------** 需要特别注意的是,新语法必须用TRY CATCH,或在查询前,用LINE_EXISTS()判断是否存在,否则将会导致DUMP **
TRY . ls_acd = lt_acd[ rbukrs = '333' ].CATCH cx_sy_itab_line_not_found . MESSAGE '未找到数据' TYPE 'E' .ENDTRY."或
IF line_exists( lt_acd[ rbukrs = '333' ] ). ls_acd = lt_acd[ rbukrs = '333' ].ELSE. MESSAGE '未找到数据' TYPE 'E' .ENDIF.由于老语法可以使用二分法查找,因此在效率上将会有差异。
现编写一个实例,循环2万条数据GT_ACD,并循环查询有14万条数据的LT_ACD中对应的值。下边测试各种情况下的查询速度
## ** 2.1、新语法 **
"-----------------------------@斌将军-----------------------------"1.测试新语法------------------------------------GET TIME STAMP FIELD lv_current1.CLEAR:lv_index.LOOP AT gt_acd INTO gs_acd. lv_index = lv_index + 1. TRY . ls_acd = lt_acd[ rbukrs = gs_acd-rbukrs gjahr = gs_acd-gjahr belnr = gs_acd-belnr docln = gs_acd-docln ]. CATCH cx_sy_itab_line_not_found . MESSAGE '未找到数据' TYPE 'E' . ENDTRY.ENDLOOP.GET TIME STAMP FIELD lv_current2."-----------------------------@斌将军-----------------------------结果:
## ** 2.2、老语法READ **
"-----------------------------@斌将军-----------------------------"2.测试老语法------------------------------------GET TIME STAMP FIELD lv_current1.CLEAR:lv_index.LOOP AT gt_acd INTO gs_acd. lv_index = lv_index + 1. READ TABLE lt_acd INTO ls_acd WITH KEY rbukrs = gs_acd-rbukrs gjahr = gs_acd-gjahr belnr = gs_acd-belnr docln = gs_acd-docln. IF sy-subrc EQ 0.
ENDIF.ENDLOOP.GET TIME STAMP FIELD lv_current2."-----------------------------@斌将军-----------------------------结果:
## ** 2.3、老语法READ二分查找 **
"-----------------------------@斌将军-----------------------------GET TIME STAMP FIELD lv_current1.CLEAR:lv_index.SORT lt_acd BY rbukrs gjahr belnr docln.LOOP AT gt_acd INTO gs_acd.
READ TABLE lt_acd INTO ls_acd WITH KEY rbukrs = gs_acd-rbukrs gjahr = gs_acd-gjahr belnr = gs_acd-belnr docln = gs_acd-docln BINARY SEARCH. IF sy-subrc EQ 0. lv_index = lv_index + 1. ENDIF.ENDLOOP.GET TIME STAMP FIELD lv_current2."-----------------------------@斌将军-----------------------------结果:< 1s
## ** 2.4、新语法+排序表 **
"-----------------------------@斌将军-----------------------------"4.测试新语法+排序表------------------------------------DATA:lt_acd_sort TYPE SORTED TABLE OF acdoca WITH NON-UNIQUE KEY rbukrs gjahr belnr docln.lt_acd_sort = lt_acd.GET TIME STAMP FIELD lv_current1.CLEAR:lv_index.LOOP AT gt_acd INTO gs_acd. lv_index = lv_index + 1. TRY . ls_acd = lt_acd_sort[ rbukrs = gs_acd-rbukrs gjahr = gs_acd-gjahr belnr = gs_acd-belnr docln = gs_acd-docln ]. CATCH cx_sy_itab_line_not_found . MESSAGE '未找到数据' TYPE 'E' . ENDTRY.ENDLOOP.GET TIME STAMP FIELD lv_current2."-----------------------------@斌将军-----------------------------结果:< 1s
综上所述:不使用二分查找,则新老语法都很慢。使用二分查找或新语法搭配排序表,则速度都有非常明显的提升