What are partial, alternate,, artificial, compound and natural key?

1.	What are partial, alternate,, artificial, compound and natural key?
Answer» 1. Partial 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. 2. Alternate Key: All Candidate Keys excluding the Primary Key are known as Alternate Keys. 3. 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. 4. 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. 5. 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.

Answer»

1. Partial 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.

2. Alternate Key: All Candidate Keys excluding the Primary Key are known as Alternate Keys.

3. 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.

4. 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.

5. 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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