# Users and authorization identifiers

User names within the Derby system are known as authorization identifiers. The authorization identifier is a string that represents the name of the user, if one was provided in the connection request.

For example, the built-in function CURRENT_USER returns the authorization identifier for the current user.

Once the authorization identifier is passed to the Derby system, it becomes an `SQL92Identifier`. An `SQL92Identifier` -- the kind of identifier that represents database objects such as tables and columns -- is case-insensitive (it is converted to all caps) unless it is delimited with double quotes, is limited to 128 characters, and has other limitations.

User names must be valid authorization identifiers even if user authentication is turned off, and even if all users are allowed access to all databases.

For more information about `SQL92Identifiers`, see the Derby Reference Manual.

- Authorization identifiers, user authentication, and user authorization
  When working with both user authentication and user authorization, you need to understand how user names are treated by each system.
- User names and schemas
  User names can affect a user's default schema.
- Exceptions when using authorization identifiers
  Specifying an invalid authorization identifier in a database user authorization property raises an exception. Specifying an invalid authorization identifier in a connection request raises an exception.

Parent topic: Understanding identity in Derby
Related concepts
Database Owner