What are database constraints used for?

Database constraints are vital components used to enforce rules and limitations on the data within a database. They help maintain data integrity by ensuring that the data adheres to certain conditions, such as format, uniqueness, and relationship with other data. For instance, constraints can be used to specify that a particular field must contain unique values (like email addresses), or that a field cannot be left empty. By establishing these rules, constraints ensure that the data remains accurate, consistent, and reliable throughout its lifecycle.

In contrast, the other options do not accurately describe the primary purpose of database constraints. While data backups are important for data recovery, they are not related to constraints. Enhancing user accessibility pertains more to the usability and design of the user interface rather than data integrity. Finally, while managing records is a database function, the deletion of unnecessary records is a separate task and not a function of constraints. Database constraints specifically focus on maintaining the quality and validity of data within the structure of the database itself.