mongodb的查询命令对应的sql命令：https://blog.csdn.net/weixin_42726306/article/details/90208031
mongodb的更新、保存常用命令：https://blog.csdn.net/qq_16664643/article/details/52217315?utm_medium=distribute.pc_relevant.none-task-blog-2defaultbaidujs_baidulandingword~default-12-52217315-blog-82022916.235v43pc_blog_bottom_relevance_base7&spm=1001.2101.3001.4242.7&utm_relevant_index=15
技术解读)
