What is secondary key and alternate key?

What is the secondary key?

Secondary Key is the key that has not been selected to be the primary key. However, it is considered a candidate key for the primary key. Therefore, a candidate key not selected as a primary key is called secondary key. Candidate key is an attribute or set of attributes that you can consider as a Primary key.

What is alternative key?

Alternate keys are those candidate keys which are not the Primary key. There can be only one Primary key for a table. Therefore all the remaining Candidate keys are known as Alternate or Secondary keys.

What is alternate key with an example?

All the keys which are not primary key are called an Alternate Key. Example: In this table, StudID, Roll No, Email are qualified to become a primary key. But since StudID is the primary key, Roll No, Email becomes the alternative key.

What is candidate key and alternate key?

Candidate key: A column or a set of columns can be called as candidate key if they identify each row of a table uniquely. A table can have multiple candidate keys. One of them is specified as Primary key and rest of them can be called as alternate key.