ABAP_to_the_Future

2
New Language Features in ABAP 7.4
2.6.7 Internal Table Queries with REDUCE
In Section 2.2.5, you learned a new way to create internal tables by using a FOR
loop. After you’ve filled up your internal tables, though, you often want to query
them. Say, for example, that you want to know how many really mad monsters
you have. As of 7.4, you can do this by using a constructor operator called REDUCE,
which contains logic to process an internal table and return a single result. In the
example in Listing 2.63, you will first say what variable you want created and
what type that variable is going to be, thenset an initial value for your result variable,
and finally loop over the table, performing assorted logic. That sounds really
complicated, but as you will see the code is not.
DATA:( ld_mad_monsters_count ) = REDUCE sy-tabix(
INIT result = 0
FOR ls_monsters IN lt_neurotic_monsters
NEXT result = result +
lo_checker->is_it_mad( ls_monsters-monster_number ).
Listing 2.63 How Many Really Mad Monsters?
The SY-TABIX after the REDUCE statement defines the type of the variable being
created, LD_MAD_MONSTER_COUNT. It also defines the type of the temporary variable
after the INIT statement, which is going to be the result; i.e., both LD_MAD_MON-
STER_COUNT and RESULT have the type SY-TABIX. You then loop over your internal
table, and every time your is_it_mad method comes back with a value of 1, you
increase the count of the RESULT variable. After the FOR loop is finished, the value
of RESULT gets copied into LD_MAD_MONSTERS.
2.6.8 Grouping Internal Tables
You are most likely familiar with the GROUP BY addition you can add to a database
SELECT, which condenses similar records into a single row. In the past, when you
wanted to do something similar to an internal table you would maybe use the
COLLECT statement or the very dodgy AT NEW statement, which did not work very
well in a lot of circumstances. In fact, the AT NEW statement was so unpredictable
that it was wiser to avoid it altogether and use other means to process related
chunks from your internal table. ABAP 7.4 brings good news: a GROUP BY option
has been added to looping at internal tables.
To understand what this means, let’s lo ok at an example. Say that you have a
huge great table of open customer items.You only want to process one customer
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