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Which of these statements, related to data abstraction, are true and which are false?
A DBMS represents data with three levels of data abstraction.
The conceptual level describes how data is actually stored in the database.
The logical level describes data as they are seen by end users.
The physical level represents the actual installation of the archives on the data storage.
The logical level is derived from the physical level.
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Which of these statements, related to E/R data model, are true and which are false?
The E/R data model is an object level data model.
Only entities can have attributes.
A relationship between an entity and itself is called recursive relationship.
A relationship between the entities E1 and E2 is said a one to many relationship when each instance of E1 corresponds to one or more instances of E2 and each instance of E2 corresponds to one or more instances of E1.
An entity has meaning only with other entities or relationships.
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