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If you
have defined a relationship between a supertype and another table,
you can join any subtypes to that other table using the same
relationship.
Suppose parent table "Super1"
has a relationship with role "HAS" and co-role "OF" to child table
"Other1". If "Super1" has a subtype table "Sub1", then you can use
the same relationship to join "Sub1" to "Other1", because "Sub1"
inherits the relationship from its supertype "Super1":
SELECT ...
FROM Sub1, Other1
RELATE Sub1 "HAS" Other1
WHERE ...
or, if for some reason you use
conventional join syntax rather than RELATE:
SELECT ...
FROM Sub1, Other1
WHERE Sub1.<primary key> =
Other1.<foreign key>
AND ...
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