Is unique key Alternate Key?

Is unique key and Alternate Key same?

Primary Key ==> Is used to uniquely identify records and doesn't allow NULL values. Unique Key ==> Is also used to uniquely identify records but does allow NULL Values per column combination. Alternate Key ==> Is another type of Unique key, which is used to identify each record uniquely. This is not a constraint.

Which key is a unique key?

The primary key is a unique or non-null key that uniquely identifies every record in that table or relation. The primary key column cannot store duplicate values that mean primary key column values are always unique.

What is Alternate Key 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.

Are unique keys primary keys?

Primary Key is a column that is used to uniquely identify each tuple of the table. It is used to add integrity constraints to the table. Only one primary key is allowed to be used in a table. ... Difference between Primary Key and Unique Key.Primary KeyUnique Keypresent in a tablepresent in a table