安装plsql，不用安装oracle客户端

1. 首先安装plsql，安装教程见
   https://www.cnblogs.com/yuxiaole/p/9349601.html
2. 下载instantclient
   https://www.oracle.com/database/technologies/instant-client/winx64-64-downloads.html
3. 配置环境变量
   教程见http://www.imooc.com/article/253169?block_id=tuijian_wz