ABAP_to_the_Future

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ABAP Programming for SAP HANA
HANA, like CDS views. You can create a CDS view in SAP HANA alone, but in this
example you’re going to create one from the ABAP environment.
Say that you want to create a view in SE11 to get all the details of monsters who
own certain pets. The first thing you woul d do is to create a database view in
SE11 and then choose what tables to join—for example, connect the monster
items to the main monster table (which the system achieves by comparing foreign
key relationships and thus doing a join on MONSTER_NUMBER) and then make a big
list of fields from one or more of the linked database tables. Next, you might add
some hard-coded selection criteria (e.g., you’re only interested in green monsters
or monsters with sanity less than 10%).
However, if you wanted to do an outer join between the monster table and the
monster pets table and also on MONSTER_NUMBER to get the details of what pets, if
any, the monster owns , then you’d be out of luck. You can’t do outer joins in an
SE11 database view. You have to create th e view linking the fi rst two tables, and
then do the outer join in your program via a SELECT statement between the newly
created view and the monster per table. View creation in SE11 works well, but like
all form-based development in ABAP, it’s somewhat clunky and involves clicking a
lot of buttons, choosing options on pop-up screens, and moving from tab to tab.
Luckily, thanks to SAP HANA, there is now a new ABAP repository object that
you can create that not only is less clun ky but also gives you more options. The
name of the ABAP repository object is DDL (Data Definition Language), and it
looks like a tiny program consisting of one complicated SELECT statement. When
the DDL object is generated in the ABAP system, an equivalent view is generated
within SAP HANA, called a CDS view. (The cut-down version of a CDS view can
be seen in SE11 but not changed.) What’s even better is that this technique works
with any database, not just SAP HANA.
To recap, instead of the form-based approach of view creation using SE11, you’re
specifying everything using code.
The steps in building and calling a CDS view can be broken down as follows:
1. Creating a DDL in Eclipse.
2. Coding the DDL.
3. Generating the CDS view in the database from the DDL.
Each step is discussed in more detail next.
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