CDS Syntax

Cast Operations

cast(myunit as abap.unit(3)) as myunit,

key cast(spras as sylangu preserving type) as spras,

Case

    case when myquantity < 30 then '<' else '>' end as comp,
    case myquantity when 30 then '=' else '<>' end as equ

Session Variables

define view Z_ViewWithSessionVariables
  as select from t000
{
  $session.client as ClientField, //sy-mandt
  $session.system_date as SystemDateField, //sy-datum
  $session.system_language as SystemLanguageField, //sy-langu
  $session.user as UserField //sy-uname
} where mandt = $session.client

Join

define view Z_ViewWithLeftOuterJoin
  as select from Z_ViewAsDataSourceD
  left outer to many join Z_ViewAsDataSourceE
    on Z_ViewAsDataSourceD.FieldD2 = Z_ViewAsDataSourceE.FieldE1


define view Z_ViewWithoutAssociationPaths
  as select from ZI_SalesOrderScheduleLine as SL
  left outer to one join ZI_SalesOrderItem as ITEM
    on ITEM.SalesOrder = SL.SalesOrder

You should always specify the maximum target cardinality (TO ONE or TO MANY) of a left outer join partner. On one hand, this specification is used to document the composition of the CDS view. On the other hand, this information can optimize the processing of a selection request in the database.
However, if you maintain the cardinality information, you should make sure that it's defined correctly. Otherwise, the selection result may become incorrect.

Aggregation Functions

@AbapCatalog.sqlViewName: 'Z21_V_AGGR'
@AbapCatalog.compiler.compareFilter: true
@AbapCatalog.preserveKey: true
@AccessControl.authorizationCheck: #CHECK
@EndUserText.label: 'Aggregations'
define view z21_c_aggr as select from Z21_C_Item {
    key mykey,
    avg( myquantity ) as myavg,
    min( myquantity ) as mymin,
    max( myquantity ) as mymax,
    count(*) as mycount
} group by mykey

Association

Cardinality	Min/Max
default	0-1
[1]	0-1
[0..1]	0-1
[1..1]	1-1
[0..*]	0-∞
[1..*]	1-∞

Parameters

CDS: Z21_C_type_param

@AbapCatalog.sqlViewName: 'Z21_VP_TYPE'
@AbapCatalog.compiler.compareFilter: true
@AbapCatalog.preserveKey: true
@AccessControl.authorizationCheck: #CHECK
@EndUserText.label: 'CDS Type with param'
define view Z21_C_type_param
 with parameters p_lang: sylangu
 as select from Z21_C_Type {
    key mytype,
    mytext
} where spras = $parameters.p_lang

SQL View for a parametric view in ABAP code

SELECT
   Z21_C_TYPE_PARAM~MYTYPE,
   Z21_C_TYPE_PARAM~MYTEXT
 FROM
  Z21_C_TYPE_PARAM( P_LANG = 'T' )

Conversion

{
unit_conversion( quantity => OrderQuantity,
                 source_unit => OrderQuantityUnit,
                 target_unit => :P_DisplayUnit,
                 error_handling => 'FAIL_ON_ERROR' ) as mynewquantity

}

Associations

Annotations