1.根据上述语义画出ER图
2将ER模型转换成数据表,并指出每个数据表的主键
![~]`SQSUHSQWOAN0H2$B1{NU.png](https://upload-images.jianshu.io/upload_images/11121211-47294d9339261b3b.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)
![~]`SQSUHSQWOAN0H2$B1{NU.png](https://upload-images.jianshu.io/upload_images/11121211-47294d9339261b3b.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/1240)