Partial Key: It is a group of attributes that can uniquely identify small entities and that are related to same base entity. It is sometime named as Discriminator.

 Alternate Key: All Candidate Keys remaining the Primary Key are called as Alternate Keys.

 Artificial Key: If no obvious key either compound or stands alone is available, then the last resort is to simply give a key, by assigning a distinct number to every occurrence or record. Then this is called as developing an artificial key.

 Compound Key: If no single data component uniquely identifies occurrences within a developed, then combining multiple components to make a distinct identifier for the construct is called as creating a compound key.

 Natural Key: When one of the data components stored within a construct is used as the primary key, and then it is known the natural key.