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What are partial, alternate,, artificial, compound and natural key?
Partial Key: It is a set of attributes that can uniquely recognize weak entities and that are related to same owner entity. It is sometime known as Discriminator.
Alternate Key: All Candidate Keys excluding the Primary Key are called as Alternate Keys.
Artificial Key: If no obvious key either stands alone or compound is available, then the last resort is to simply make a key, by assigning a unique number to every record or occurrence. Then this is known as developing an artificial key.
Compound Key: If no single data element uniquely identifies occurrences within a construct, then combining multiple elements to make a unique identifier for the construct is known as creating a compound key.
Natural Key: When one of the data elements stored within a construct is utilized as the primary key, then it is known as the natural key.
Explain the Weak Entity Set An Entity set which does not have sufficient attribute to make a primay key is known as weak entity set. For instance, dependents of an employee in
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