不推薦
Select * from zflight.
Check : zflight-airln = ‘LF’ and zflight-fligh = ‘BW222’.
Endselect.
推薦
Select * from zflight where airln = ‘LF’ and fligh = ‘BW222’.
Endselect.
2、使用聚合函數
不推薦
Maxnu = 0.
Select * from zflight where airln = ‘LF’ and cntry = ‘IN’.
Check zflight-fligh > maxnu.
Maxnu = zflight-fligh.
Endselect.
推薦
Select max( fligh ) from zflight into maxnu where airln = ‘LF’ and cntry = ‘IN’.
3、使用視圖代替基本表查詢
不推薦
Select * from zcntry where cntry like ‘IN%’.
Select single * from zflight where cntry = zcntry-cntry and airln = ‘LF’.
Endselect.
推薦
Select * from zcnfl where cntry like ‘IN%’ and airln = ‘LF’.
Endselect.
4、使用INTO table 代替select endselect
不推薦
Refresh: int_fligh.
Select * from zflight into int_fligh.
Append int_fligh. Clear int_fligh.
Endselect.
推薦
Refresh: int_fligh.
Select * from zflight into table int_fligh.
5、使用批量修改內表代替逐行修改
不推薦
Loop at int_fligh.
If int_fligh-flag is initial.
Int_fligh-flag = ‘X’.
Endif.
Modify int_fligh.
Endloop.
推薦
Int_fligh-flag = ‘X’.
Modify int_fligh transporting flag where flag is initial.
6、使用二分法查詢，提高查詢內表數據速度
不推薦
Read table int_fligh with key airln = ‘LF’.
推薦
Read table int_fligh with key airln = ‘LF’ binary search.
SAP ABAP 性能優化技巧 — 使用二分查找(Binary Search)選項
READ命令使用順序查找數據表，這會降低處理速度。取而代之，使用binary search的附加命令，可以使用二分查找算法，可以幫助加快內表查找速度。 在使用binary search之前必須首先將內表排序，否則有可能找不到記錄，因爲二分查找反覆將查找區間對半劃分，如果要查找的值小於查找區間的中間位置的數據項值，則查找區間將縮小到前半個區間，否則查找將侷限於後半區間.
不推薦使用：
Read table int_fligh with key airln = ‘LF’.
推薦使用：
SORT int_fligh by airln.
Read table int_fligh with key airln = ‘LF’ binary search.
應用：
with key 後面不能使用比較符 < >.
read table itab with key matnr = lt_mseg_n-matnr
pvprs > 0 . 這種寫法不對。
可以變通的寫這條語句。
LOOP at lt_ckmlcr WHERE matnr = lt_mseg_n-matnr AND pvprs > 0.
.........
exit.
endloop.
7、兩個內表添加使用批量增加代替逐行
不推薦
Loop at int_fligh1.
Append int_fligh1 to int_fligh2.
Endloop.
推薦
Append lines of int_fligh1 to int_fligh2.
8、 使用FOR ALL Entries
不推薦
Loop at int_cntry.
Select single * from zfligh into int_fligh where cntry = int_cntry-cntry.
Append int_fligh.
Endloop.
推薦
Select * from zfligh appending table int_fligh
For all entries in int_cntry
Where cntry = int_cntry-cntry.
9、使用sort by 代替order by
10、避免使用SELECT DISTINCT語句
使用的 ABAP SORT + DELETE ADJACENT DUPLICATES 代替.
11、兩個實例
DATA: BEGIN OF it_mara OCCURS 0,
matnr LIKE mara-matnr,
maktx LIKE makt-maktx,
END OF it_mara.
第一種寫法:
Select matnr
INTO it_mara
FROM mara.
APPEND it_mara.
ENDSelect.
第二種寫法(high performace):
Select matnr
INTO TABLE it_mara
FROM mara.
==========================================
DATA: BEGIN OF it_mara OCCURS 0,
matnr LIKE mara-matnr,
maktx LIKE makt-maktx,
END OF it_mara.
DATA: BEGIN OF it_makt OCCURS 0,
matnr LIKE mara-matnr,
maktx LIKE makt-maktx,
END OF it_makt.
第一種寫法:
LOOP AT it_mara.
Select SINGLE maktx
INTO it_mara-maktx
FROM makt
Where matnr = it_mara-matnr AND
spras = sy-langu.
MODIFY it_mara TRANSPORTING maktx.
ENDLOOP.
第二種寫法(high performace)
Select matnr maktx
INTO TABLE it_makt
FROM makt
FOR ALL ENTRIES IN it_mara
Where matnr = it_mara-matnr and
spras = sy-langu.
=========================================
1 數據——>工作區，工作區——>內表，
2 數據——>內表
很明顯少了一個過程 效率自然高了 如果數據量越大,效果是可想而知的