Recommendation for a good entity relationship diagram building tool for occasional usage?

Create a diagram for existing database schema or its subset as follows:

1. Click File → Data Modeler → Import → Data Dictionary.
2. Select a DB connection (add one if none).
3. Click Next.
4. Check one or more schema names.
5. Click Next.
6. Check one or more objects to import.
7. Click Next.
8. Click Finish.

The ERD is displayed.

Export the diagram as follows:

1. Click File → Data Modeler → Print Diagram → To Image File.
2. Browse to and select the export file location.
3. Click Save.

The diagram is exported. To export in a vector format, use To PDF File, instead. This allows for simplified editing using Inkscape (or other vector image editor).

These instructions may work for SQL Developer 3.2.09.23 to 4.1.3.20.

Take this with a grain of salt as I'm not 100% sure:

• The Employee shoud have a foreign key to the Hotel_code (assuming one employee does not work for multiple hotels)
• The hotel does not have a foreign key to the employee
• The reservation should have a foreign key to the hotel_code
• The Guest does not need a foreign key to the reservation
• Guest_Id should not be part of reservations PK
• the bill should have a foreign key to the reservation instead of to the guest
• the reservation could have additional information about the duration of the stay
• the room does not need a guest_id and res_nr