这个是我收集的几个ER图。
[img]http://gnn.iteye.com/upload/picture/pic/40682/03fe2ff3-33d2-3e08-b89e-fb62d7c38600.gif[/img]
[img]http://gnn.iteye.com/upload/picture/pic/40680/a178e6cc-ff04-31cb-a898-fd6b9937086d.jpg[/img]
[img]http://gnn.iteye.com/upload/picture/pic/40678/273bf72f-7720-3e32-a053-5cfecc99dcc0.gif[/img]
[img]http://gnn.iteye.com/upload/picture/pic/40676/21386d5e-537e-3364-bcd3-8fb09d0cc94b.gif[/img]
[img]http://gnn.iteye.com/upload/picture/pic/40674/b11eb4ce-91d0-31c9-9491-0f0b08f49d23.jpg[/img]
[img]http://gnn.iteye.com/upload/picture/pic/40672/8e35853a-e5e6-38a3-991c-e2f85b0533a3.gif[/img]