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Plan or blueprint for a database design. It's more generalized and abstract than design. It's easier to change than a design.
Attributes that name, or identify entity instances. The Consists of one or more of the entity's attributes
The entity on the one side of the relationship is called the parent entity . The entity on the child side of the relationship is called the child entity.
Zero if participation in the relationship is optional, 1 if the relationships is required or mandatory. (hash mark)
Cannot indicate true minimum cardinalities on N:M relationships. Must use intersection table instead of true N:M model.
ID-Dependent Entities Properties
Minimum cardinality to the parent is always one (required.) A solid line is used to identify ID-dependent entities.
Weak entity properties
All ID-Dependent entities are weak, but not all weak entities are ID-dependent. Indicated by non-identifying relationship
One supetype relates to at most one subtype. Ex. Employee can be a manager or DB Admin, but not both.
Strong entity relationships because each entity instance HAS A relationship with another entity instance.
Supertypes/Subtypes relationships are called IS-A relationships because a subtype IS A supertype.
Data model process 2
Identify all potential entities, including identifier and attributes for each entity
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