数据库操作	Mongodb	MySQL
查询库	show databases | show dbs	show databases
选中库	use databaseName	use databaseName
查询表	show tables | show collections	show tables
创建表	db.createCollection(‘collectionName’)	create table tableName...
删除表	db.collectionName.drop	drop table tableName
删除库	db.dropDatabase	drop database databaseName
添加表数据	db.collectionName.insert	insert
查询表数据	db.collectionName.find	select
修改表数据	db.collectionName.update	update
删除表数据	db.collectionName.remove	delete

如上述所示,mongodb同样兼容了部分传统数据库的命令,其中有必要说一下的是mongodb中创建库采用的是隐式创建,即在use 一个不存在的库时就会变为创建库,use databaseName 有则选中无则创建,但这里还没有创建完毕,需要进一步创建表才算创建完毕;同时创建表时也允许隐式创建,即db.collectionName.insert 往一个不存在的表中添加数据就会先创建表再添加数据

一:常用命令

1.1:查看当前的数据库

> show dbs
admin   0.000GB
config  0.000GB
local   0.000GB
shop    0.000GB
> show databases
admin   0.000GB
config  0.000GB
local   0.000GB
shop    0.000GB

1.2:选中库

> use shop
switched to db shop

1.3:查看表

> show collections
user
> show tables
user　　

1.4.1:创建库/表

> use good
switched to db good
> db.createCollection('items')　　
{ "ok" : 1 }

1.4.2:创建库/表第二种方式

> use cate
switched to db cate
> db.cateList.insert({"_id":1,"cateName":"FAST"})
WriteResult({ "nInserted" : 1 })

1.4.3:在创建库时如果没有创建表,库也会创建失败

> use cate
switched to db cate
> show dbs
admin   0.000GB
config  0.000GB
good    0.000GB
local   0.000GB
shop    0.000GB

1.5:删除表

> db.cateList.drop()
true

1.6:删除库

> use good 
switched to db good
> db.dropDatabase()
{ "dropped" : "good", "ok" : 1 }

1.7:使用db.help()查看更多方法

> 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) - deprecated
        db.commandHelp(name) returns the help for the command
        db.copyDatabase(fromdb, todb, fromhost) - deprecated
        db.createCollection(name, {size: ..., capped: ..., max: ...})
        db.createView(name, viewOn, [{$operator: {...}}, ...], {viewOptions})
        db.createUser(userDocument)
        db.currentOp() displays currently executing operations in the db
        db.dropDatabase()
        db.eva l() - 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.getPrevError()
        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() g