1.基础语法: 相关网站: http://www.runoob.com/mongodb/mongodb-query.html
Noted: 1> can not order by multiple fields.
2> better to use object array , not use a string to save a array data.
2.链接DB工具 1> nosqlbooster : https://nosqlbooster.com/downloads
2> studio 3T : https://studio3t.com/download-now/ win版破解方法网站: https://www.jianshu.com/p/cc97f31509ea