Description: The Unique Key is a field or combination of fields that uniquely identifies a record in a table within a database. Its main function is to ensure data integrity by preventing duplicate records and ensuring that each entry is unique. This is fundamental in the design of relational databases, where each table must have at least one unique key to effectively relate to other tables. Unique keys can be simple, like an identification number, or composite, combining several fields to form a unique identifier. Additionally, unique keys are essential for query optimization, as they allow for faster access to data. In SQL, unique keys can be defined using the UNIQUE constraint when creating or modifying a table, which helps maintain the quality and accuracy of the stored information. In summary, the Unique Key is a critical component in database structure, ensuring that each record is easily identifiable and accessible.
