Unique Key

A unique key is a specific identifier used in a database to ensure that each record (or row) can be distinguished from all others. Unlike a primary key, a table can have multiple unique keys. Each unique key guarantees that the values in its associated column(s) are different for every record, preventing duplicate entries. This helps maintain data integrity and enables quick and accurate data retrieval. For example, an email address in a user database can be a unique key because no two users should have the same email address.