Some curd operations of MongoDB

Some additions and deletions of MongoDB change the command operation: Official document reference https://docs.mongodb.com/manual/reference/method/

　　

#查看当前mongod下有哪些数据库: Show dbs# enters or creates a database: UseDatabase name Use db_name#查看当前数据库下, which collections (tables): Show tables or show collections# create a collection, (insert a document directly) DB. Collection name.Insert({a:1}) #更新文档db. Collection name.Update(Query,Update,option#删除文档db. Collection name. Remove (query, Justone) #查询文档db. Collection name. Find (query, projection) #创建索引db. Collection name. CreateIndex (Keys, Options) #删除当前数据库db. Dropdatabase () #删除表db. Collection name.Drop() #排序sort # Skip and Limitskip limit# common aggregations when queryingCount、Group, aggregate, mapReduce, etc.

　　

Create or a database,

Some curd operations of MongoDB