All instances of the supertype _____ be an instance of one of the subtypes. Mark for review (1) points will sometimes may cannot must
Answers
Answer : - All attributes of the supertype are common to all the instance subtypes.
Supertype represent common set of attributes.
Subtypes represent unique attributes.
An occurrence of Subtype entity represents an occurrence of the same Supertype entity. Primary keys of both supertype and subtype is same.
The cardinality Maximum:Minimum between the supertype and subtype are 1:0 always.
All instances of the supertype can be an instance of one of the subtypes.
They are also common to different kinds of instance subtypes.
The supertype actually represents the common attributes set.
When it comes to subtypes, they are the specialized sets which show the unique attributes.
A happening of subtype entity actually represents the occurrence of similar type of Supertype entity.