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An entity type usually has an attribute whose values are distinct for every individual entity in the collection. Such an attribute is known as a key attribute and its values can be used to recognize each entity uniquely.
Strong entity set: The entity types having a key attribute are known as strong entity types or regular entity types.
Attributes
Let us first answer the question:
What is an attribute?
An attribute is a property used to define the specific feature of the entity. So to define an entity entirely, a set of attributes is used.
For example, a student entity may be defined by the student's name, address, age, course, etc.
An entity will have a value for every of its attributes. For example for a specific student the following values can be assigned:
RollNo: 1234
Name: Supriya
Age: 18
Address: B-4, Mayapuri, Delhi. Course: B.Sc. (H)
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About Attribute inheritance
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Complete replication: It implies maintaining of a whole copy of the database at every site. Thus, the reliability & availability and performance for query response are maximized.
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