What are partial, alternate, artificial, compound and 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.
All Candidate Keys excluding the Primary Key are known as Alternate Keys.
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.
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.
When one of the data elements stored within a construct is utilized as the primary key, then it is called the natural key.