ABAP_to_the_Future

Recent Code Inspector Enhancements 4.3
Let’s turn, once again, to the ongoing monster example. As you know, monsters
tend to hide under beds, so you want to do a database query to find out what
beds the monsters selected earlier have been hiding under (Listing 4.5).
DATA: lt_beds TYPE STANDARD TABLE OF ztvc_monstr_beds.
SELECT *
FROM ztvc_monstr_beds
INTO CORRESPONDING FIELDS OF TABLE lt_beds
FOR ALL ENTRIES IN lt_monsters
WHERE monster_number EQ lt_monsters-monster_number.
Listing 4.5 SELECT * Check for Monsters under the Bed
If you take a look at this code, you can probably tell that an inner join is a better
choice than what’s been done here. Will ATC tell you the same thing? Set up the
check as in Figure 4.20 to find out.
Figure 4.20 Improving FOR ALL ENTRIES
Sure enough, the warning in Figure 4.21 tells you to improve the structure of
your code so that you only have one SELECT statement. The reason for the warning
is that if you were to take two pr ograms, both selecting the same data, one
using an inner join and one using a FOR ALL ENTRIES, and run them one at a time,
each time using Transaction ST05 to pe rform an SQL trace, then you would find
that an inner join has only one SQL entry no matter what, whereas a FOR ALL
ENTRIES has a large number of SQL entries increasing in a linear fashion with the
amount of data to be retrieved.
Figure 4.21 FOR ALL ENTRIES Error Message
197