Linking record types Schema DDL
80 U929-J-Z125-9-76
Example 1
Figure 18: Example of OPTIONAL AUTOMATIC
The link between a CUSTOMER-ORDER record and a CUSTOMER record is relatively
stable. An order only exists if a customer has placed one. The link to the owner record i s
thus automatic at the time the CUSTOMER-ORDER record is stored. Filled orders are to
remain in the database for statistical purposes even when the link to t he CUSTOMER
record no longer exists. This is why the set membership is defined as OPTIONAL.
CUSTOMER-
CUSTOMER-ORDERS-PLACED
(OPTIONAL AUTOMATIC)
CUSTOMER
ORDER