Computer room reconfiguration-database design

Database Design--Conceptual design phase

This stage is mainly based on the need to draw ER figure, as shown, is I draw according to the demand of the computer room charge system ER figure, the figure has 6 entities, respectively: teachers, students, cards, basic data, bills, computers, there are a pair of relationships between them have many-to-many relationships, including teachers have a lot of different roles, there is no subdivision, but in the future we will do security mechanism design will be carefully treated. According to the principle of conversion, but when we convert the ER diagram into a table, many-to-many relationships draw out a table, so that in the logical design phase we can get the corresponding ten tables (the computer has only one property, therefore omitted).

Database design--Logic design phase

I was based on ER the resulting table (which is represented in the class diagram first, and none of the classes correspond to a single table).

Database in the late there are many needs to improve the place, here first to do a simple design, the shortcomings are also please advise.

Computer room reconfiguration-database design