1, create a new entity EJB in the EJB module, change four class names, add EJB attribute values
2, generate EJB to RDB mapping -> Using existing backend folders -> Create and map unmapped elements
3. Open the mapping -> Open the table editor, change the name, primary key, foreign key, column (corresponding to the table of the database)
4. ASSEMBLYDESCRIPTOR, join the container transaction
5, verification, refresh, generate deployment code
6, debug or run EJB, do not select when Oracle
