Master-Detail Links

First diagram has DETAIL table with Primary Key and Foreign Key.

Doesn't the primary key consist of a pair of field lists that determine uniqueness with
one of the field lists consisting of fields that uniquely identify a record in another
table?

That is, doesn't the definition of primary key for the detail table necessarily contain
all fields?

Is this diagram suggesting that there -ought to- be a unique identifier for each record
rather than unique within distinct master keys?

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Raymond Kennington
Programming Solutions
W2W Team B