Using Caché Objects - InterSystems Documentation

Objects and SQL
SELECT ID,Name,Title,TheCompany->Name
FROM Employee
ORDER BY Name
The multi-valued side is not projected as a field (Multi-valued relationships are state-less on
disk and SQL does not deal with in-memory objects). Instead, you must perform a simple
join based on the multi-valued side's ID value and the single-valued side's reference field:
SELECT c.Name, e.Name
FROM Company c, Employee e
WHERE e.TheCompany = c.ID
ORDER By 1,2
A single-valued relationship with cardinality of ONE is projected to SQL as a FOREIGNKEY
with NOACTION specified for UPDATE and DELETE.
If the cardinality of the single-valued relationship is PARENT then the table projected from
the class containing the relationship is “adopted” as a child table by the table projected from
the type class of the single-valued relationship.
124 Using Caché Objects