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What Are Partial, Alternate, Artificial, Compound And Natural Key? |
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Answer» It is a SET of attributes that can uniquely identify weak entities and that are related to same owner entity. It is sometime called as DISCRIMINATOR. Alternate Key: All Candidate Keys excluding the Primary Key are known as Alternate Keys. ARTIFICIAL Key: If no obvious key, either stand alone or compound is AVAILABLE, then the last resort is to simply create a key, by assigning a unique number to each 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 create 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 called the natural key. It is a set of attributes that can uniquely identify weak entities and that are related to same owner entity. It is sometime called as Discriminator. Alternate Key: All Candidate Keys excluding the Primary Key are known as Alternate Keys. Artificial Key: If no obvious key, either stand alone or compound is available, then the last resort is to simply create a key, by assigning a unique number to each 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 create 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 called the natural key. |
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