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Describe the primary key functions?
Primary Key : The primary key is an attribute or a set of attributes in which uniquely identify a specific example of an entity. Every entity in the data model must have a primary key whose values uniquely recognize instances of the entity.
To qualify as a primary key for an entity, an attribute must have the subsequent properties: * It must have a non-null value for each instance of the entity. * The value must be unique for each instance of an entity * The values must not change or become null during the life of each entity instance.
Vertical Fragmentation- Vertical fragmentation groups together only those attributes in a relation that are used jointly by various important transactions. A vertical fragment is d
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The insertion of a tuple in the aim of reference does not cause any destruction. Though, insertion of a tuple in the relation in which, we has the foreign key, for instance, in ASS
Give an example of Object Representation For illustration, consider the implementation of a social security number within an employee object that is shown in Figure. The soci
What is completeness constraint on generalization? Define the variation between total and partial design constraint. Give an example each. Ans: Completeness Constraints
write on the various type of relationalkey
What are metrics for choosing the best algorithm? Matrices for choosing the best algorithms are as below: Computational complexity Ease of understand ability and im
Type of database technology
In an E-R diagram how attributes are represented ? In an E-R diagram attributes are represented in a ellipse.
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