ABAP CDS View Associations: Define Relationships & Improve Performance

SAP ABAP CDS View Association

Associations in ABAP Core Data Services (CDS) views define relationships between different database tables or views, similar to joins but with better performance and flexibility.

🔹 Basic Syntax of an Association

define view ZDEMO_CDS as select from sflight
association [0..1] to scarr as _Carrier on _Carrier.carrid = sflight.carrid
{
    key sflight.carrid,
    key sflight.connid,
    sflight.fldate,
    _Carrier.name
}

🔹 Explanation:

✅ Defines an association (_Carrier) to the scarr table. ✅ Uses ON condition (_Carrier.carrid = sflight.carrid). ✅ Selects fields from both sflight and the associated _Carrier. ✅ The [0..1] cardinality means at most one matching record.

🔹 Types of Associations

Type	Example	Meaning
[0..1]	`association [0..1] to scarr`	At most one match (like LEFT JOIN with a single record).
[1..1]	`association [1..1] to scarr`	Exactly one matching record.
*[0..]**	`association [0..*] to spfli`	Multiple matches (like LEFT JOIN with many records).

🔹 Using Associations in SELECT Queries

Associations are lazy by default (not included in the result). To retrieve data from an association, use the INNER JOIN keyword:

select from ZDEMO_CDS
   inner join _Carrier
   fields carrid, connid, fldate, _Carrier.name
   into table @DATA(result).

This explicitly fetches _Carrier.name from the associated table.

🔹 Benefits of Associations

✅ Better Performance – More efficient than traditional JOINs. ✅ Reusability – Defined once and used across multiple views. ✅ Lazy Loading – Only fetched when explicitly used in a query.

Would you like a more advanced example with multiple associations? 🚀