Schema names for objects can be specified as either regular or delimited identifiers, depending on the schema name's compliance with conventions. If a schema name contains characters unacceptable in a regular identifier, such as in Da Vinci or O'Neil, then it must be specified as a delimited identifier in double quotes.

Default schema names are created based on the user ID associated with the database connection. The user ID can be stored in uppercase, lowercase, or mixed case, depending on choices made by the DBA when the database was created. If a user ID is stored in mixed case, any schema name based on that user ID can also be stored in mixed case and must be specified as a delimited identifier, in double quotes, when qualifying an object with an owner name.

Also, you must specify any mixed‑case user ID as a delimited identifier when impersonating that user with the ‑u flag on the command line.

For more information on schema names or on specifying case conventions for user identifiers in a particular database, see the Database Administrator Guide.