MongoDB笔记

手册：https://docs.mongodb.com/manual/reference/method/db.collection.find/

1.远程连接

 docker run -it mongo bash

要连接的IP：116.85.12.51

命令：mongo 116.85.12.51:27017/meeting -u "kimkat" -p "123456"

这样就可以连接到116.85.12.51的mongodb/meeting的数据库了。

2.创建用户授权

use admin;

show users;

mgset-410052412:PRIMARY>
db.createUser(
{
user:"bch",
pwd:"kmLnBNyycD7gtBom",
roles:[{"role" : "readWrite","db" : "bitcoin_cash"}]
}
)
3.删除数据库

> show dbs

> use runoob
switched to db runoob 

> db.dropDatabase()
{ "dropped" : "runoob", "ok" : 1 }

4.删除集合

集合删除语法格式如下：

db.collection.drop()

以下实例删除了 runoob 数据库中的集合 site：

> use runoob
switched to db runoob
> db.createCollection("runoob")     # 先创建集合，类似数据库中的表
> show tables
runoob
> db.runoob.drop()
true
> show tables
> 

5. 根据条件查询表/集合数据

> show collections

   accounts

> db.collectionName.find() 或者 db.collectionName.find({})

1. > db.collection.find(query,projection)  

参数	类型	描述
query	document	可选. 使用查询操作符指定查询条件
projection	document	指定使用投影运算符返回的字段省略此参数返回匹配文档中的所有字段

       https://www.cnblogs.com/williamjie/p/9943739.html

6. 其它语法

善用help

mgset-400047458:PRIMARY> help
        db.help()                    help on db methods
        db.mycoll.help()             help on collection methods
        sh.help()                    sharding helpers
        rs.help()                    replica set helpers
        help admin                   administrative help
        help connect                 connecting to a db help
        help keys                    key shortcuts
        help misc                    misc things to know
        help mr                      mapreduce

        show dbs                     show database names
        show collections             show collections in current database
        show users                   show users in current database
        show profile                 show most recent system.profile entries with time >= 1ms
        show logs                    show the accessible logger names
        show log [name]              prints out the last segment of log in memory, 'global' is default
        use <db_name>                set current database
        db.foo.find()                list objects in collection foo
        db.foo.find( { a : 1 } )     list objects in foo where a == 1
        it                           result of the last line evaluated; use to further iterate
        DBQuery.shellBatchSize = x   set default number of items to display on shell
        exit                         quit the mongo shell
mgset-400047458:PRIMARY>

mgset-400047458:PRIMARY> db.help()
DB methods:
        db.adminCommand(nameOrDocument) - switches to 'admin' db, and runs command [just calls db.runCommand(...)]
        db.aggregate([pipeline], {options}) - performs a collectionless aggregation on this database; returns a cursor
        db.auth(username, password)
        db.cloneDatabase(fromhost) - will only function with MongoDB 4.0 and below
        db.commandHelp(name) returns the help for the command
        db.copyDatabase(fromdb, todb, fromhost) - will only function with MongoDB 4.0 and below
        db.createCollection(name, {size: ..., capped: ..., max: ...})
        db.createUser(userDocument)
        db.createView(name, viewOn, [{$operator: {...}}, ...], {viewOptions})
        db.currentOp() displays currently executing operations in the db
        db.dropDatabase(writeConcern)
        db.dropUser(username)
        db.eval() - deprecated
        db.fsyncLock() flush data to disk and lock server for backups
        db.fsyncUnlock() unlocks server following a db.fsyncLock()
        db.getCollection(cname) same as db['cname'] or db.cname
        db.getCollectionInfos([filter]) - returns a list that contains the names and options of the db's collections
        db.getCollectionNames()
        db.getLastError() - just returns the err msg string
        db.getLastErrorObj() - return full status object
        db.getLogComponents()
        db.getMongo() get the server connection object
        db.getMongo().setSlaveOk() allow queries on a replication slave server
        db.getName()
        db.getProfilingLevel() - deprecated
        db.getProfilingStatus() - returns if profiling is on and slow threshold
        db.getReplicationInfo()
        db.getSiblingDB(name) get the db at the same server as this one
        db.getWriteConcern() - returns the write concern used for any operations on this db, inherited from server object if set
        db.hostInfo() get details about the server's host
        db.isMaster() check replica primary status
        db.killOp(opid) kills the current operation in the db
        db.listCommands() lists all the db commands
        db.loadServerScripts() loads all the scripts in db.system.js
        db.logout()
        db.printCollectionStats()
        db.printReplicationInfo()
        db.printShardingStatus()
        db.printSlaveReplicationInfo()
        db.resetError()
        db.runCommand(cmdObj) run a database command.  if cmdObj is a string, turns it into {cmdObj: 1}
        db.serverStatus()
        db.setLogLevel(level,<component>)
        db.setProfilingLevel(level,slowms) 0=off 1=slow 2=all
        db.setVerboseShell(flag) display extra information in shell output
        db.setWriteConcern(<write concern doc>) - sets the write concern for writes to the db
        db.shutdownServer()
        db.stats()
        db.unsetWriteConcern(<write concern doc>) - unsets the write concern for writes to the db
        db.version() current version of the server
        db.watch() - opens a change stream cursor for a database to report on all  changes to its non-system collections.
mgset-400047458:PRIMARY>