1、使用where语句
不推荐
Select * from zflight.
Check :
zflight-airln = ‘LF’ and zflight-fligh = ‘BW222’.
Endselect.
推荐
Select
* from zflight where airln = ‘LF’ and fligh = ‘222’.
Endselect.
2、使用聚合函数
不推荐
Maxnu = 0.
Select * from zflight where
airln = ‘LF’ and cntry = ‘IN’.
Check zflight-fligh > maxnu.
Maxnu =
zflight-fligh.
Endselect.
推荐
Select max(
fligh ) from zflight into maxnu where airln = ‘LF’ and cntry = ‘IN’.
3、使用视图代替基本表查询
不推荐
Select * from zcntry where cntry
like ‘IN%’.
Select single * from zflight where cntry = zcntry-cntry and airln
= ‘LF’.
Endselect.
推荐
Select * from zcnfl where cntry like ‘IN%’ and
airln = ‘LF’.
Endselect.
4、使用INTO table 代替select endselect
不推荐
Refresh:
int_fligh.
Select * from zflight into int_fligh.
Append int_fligh. Clear
int_fligh.
Endselect.
推荐
Refresh: int_fligh.
Select * from zflight
into table int_fligh.
5、使用批量修改内表代替逐行修改
不推荐
Loop at int_fligh.
If
int_fligh-flag is initial.
Int_fligh-flag = ‘X’.
Endif.
Modify
int_fligh.
Endloop.
推荐
Int_fligh-flag = ‘X’.
Modify
int_fligh transporting flag where flag is initial.
6、使用二分法查询，提高查询内表数据速度
不推荐
Read table int_fligh with key
airln = ‘LF’.
推荐
Read table int_fligh with key airln = ‘LF’ binary
search.
7、两个内表添加使用批量增加代替逐行
不推荐
Loop at int_fligh1.
Append
int_fligh1 to int_fligh2.
Endloop.
推荐
Append lines of int_fligh1 to
int_fligh2.
8、使用table buffering
Use of buffered tables is recommended
to improve the performance considerably. The buffer is bypassed while using the
following statementsSelect distinct
Select … for update
Order by, group
by, having clause
Joins
Use the Bypass buffer addition to the select
clause in order to explicitly bypass the buffer while selecting the data.
9、 使用FOR ALL Entries
不推荐
Loop at int_cntry. Select
single * from zfligh into int_fligh where cntry = int_cntry-cntry. Append
int_fligh. Endloop.
推荐
Select * from zfligh appending table
int_fligh
For all entries in int_cntry
Where cntry = int_cntry-cntry.
10、正确地使用where语句，使查询能使用索引
When a base table has multiple
indices, the where clause should be in the order of the index, either a primary
or a secondary index
To choose an index, the optimizer checks the field names
specified in the where clause and then uses an index that has the same order of
the fields. One more tip is that if a table begins with MANDT, while an index
does not, there is a high possibility that the optimizer might not use that
index.
11、正确地使用MOVE语句
Instead of using the move-corresponding
clause it is advisable to use the move statement instead. Attempt should be made
to move entire internal table headers in a single shot, rather than moving the
fields one by one.
12、正确地使用inner join
Let us take an example of 2 tables,
zairln and zflight. The table zairln has the field airln, which is the airline
code and the field lnnam, which is the name of the airline. The table zflight
has the field airln, the airline code and other fields which hold the details of
the flights that an airline operates.
Since these 2 tables a re logically
joined by the airln field, it is advisable to use the inner join.
Select
a~airln a~lnnam b~fligh b~cntry into table int_airdet
From zairln as a inner
join zflight as b on a~airln = b~airln.
In order to restrict the data as per
the selection criteria, a where clause can be added to the above inner join.
13、使用sort by 代替order by
14、避免使用SELECT DISTINCT语句
使用的 ABAP SORT + DELETE ADJACENT
DUPLICATES 代替.
原文：http://www.cnblogs.com/ruingy/p/3599869.html