: The alternate key: All the candidate keys are known as alternate key excluding the primary keys.
Artificial key: The last resort creates the key by assigning the specific code to each record. This key is known as the artificial key.
Compound Key: When multiple elements are combined together to develop a unique identifier for the construct then it is known as the compound key.
Natural Key: the natural key refers to the key used when the data elements stored in the construct is used as the primary key.