pdm画表间结构
PDM(物理概念模型)各种属性建立如PK,AK等
https://blog.csdn.net/qq_27376871/article/details/51321609
CDM: ER图详细教程
通常在概要设计阶段,画er图,是现实世界中数据特征的抽象
https://www.cnblogs.com/yingsong/p/5072375.html
https://blog.csdn.net/dingguagua99/article/details/51317091
PowerDesigner连接mysql逆向生成pdm
https://www.cnblogs.com/dennyzhangdd/p/5550868.html