ABAP_to_the_Future

Top-Down Development 15.2
To recap, you’re going to define the name of each view field and how it is to be
filled together, one at a time. Instead of listing all the fields after the SELECT statement
as you would do in an SQL query, the list of fields and how to fill them
comes in the body of the code, after the SELECT and JOIN criteria but before the
WHERE clause. This list of fields is enclosed in curly-wurly brackets ({ }), as shown
in Listing 15.3.
{
Key monster_header.monster_number AS monster_number,
Monster_header.Monster_name AS monster_name
LPAD( monster_header.hat_size, 10, "0" ) AS hat_size
SUBSTRING( monster_header.monster_name, 0, 1 ) AS first_initial
}
Listing 15.3 List of Fields for the CDS View to Get from the Database
Once again, you are required to declare an alias every time (e.g., AS monster_
number). The target field has no explicit type declaration; it is typed according to
the value that is being passed into it. You will notice in Listing 15.3 that there are
some built-in functions: for when you want to return a hat size of 3 as
0000000003 and return the first initial of a monster called Fred as “F”. There are
bucket loads of such functions availabl e, and more creep in with each support
stack.
Back in Chapter 2, you saw that CASE statements had crept into OpenSQL statements
in ABAP, and much as you might shout “Get back! Get back! Get back to
where you once belonged!” at them, it’s a fact of life in ABAP 7.4 that CASE statements
go where they please when they please (swaggering, arrogant bullies that
they are). Here they can be used inside a CDS view, as demonstrated in Listing
15.4. You will note they can also be nested.
CASE monster_header.sanity_description
WHEN 'BONKERS' THEN 'REALLY SCARY'
WHEN 'MAD' THEN
CASE monster_header.strength_description
WHEN 'REALLY STRONG' THEN 'SCARY'
ELSE 'NOT SO SCARY REALLY'
END
WHEN 'SLIGHTLY MAD' THEN 'SLIGHTLY SCARY'
ELSE 'NOT REALLY SCARY AT ALL'
END AS scariness
}
Listing 15.4 CASE Statement within a CDS View
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