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What is the main purpose of an entity in a database design?
What is the main purpose of an entity in a database design?
- To represent an object that will have many instances in the database (correct)
- To represent a user of the database system
- To represent an output of the database system, such as a report
- To represent a concept that is not related to the database system
What is the difference between an entity type and an entity instance?
What is the difference between an entity type and an entity instance?
- An entity type is a collection of entities with common attributes, while an entity instance is a single occurrence of an entity. (correct)
- An entity type is a user of the database system, while an entity instance is an output of the database system.
- An entity type is a single occurrence of an entity, while an entity instance is a collection of entities with common attributes.
- An entity type is an abstract concept, while an entity instance is a physical object in the database.
What is the key difference between a strong entity and a weak entity?
What is the key difference between a strong entity and a weak entity?
- A strong entity has a unique identifier, while a weak entity does not.
- A strong entity is independent of other entities, while a weak entity is dependent on a strong entity.
- A strong entity is represented by a single-line underlined identifier, while a weak entity is represented by a double-line underlined identifier.
- All of the above (correct)
What is the purpose of an identifying relationship in a database design?
What is the purpose of an identifying relationship in a database design?
What is the main purpose of defining relationships in a database design?
What is the main purpose of defining relationships in a database design?
What is the purpose of modeling relationship types as lines between entity types?
What is the purpose of modeling relationship types as lines between entity types?
When does a relationship turn into an associative entity?
When does a relationship turn into an associative entity?
What does the degree of a relationship represent?
What does the degree of a relationship represent?
If the minimum cardinality of a relationship is zero, what does it indicate?
If the minimum cardinality of a relationship is zero, what does it indicate?
Which of the following statements about attributes is true?
Which of the following statements about attributes is true?
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