MongoDB基本命令

     安装完成MongoDB，了解一下MongoDB的基础知识

2 MongoDB基本命令

show dbs – 列出所有的数据库

use db_name – 切换到数据库db_name

showcollections –- 列出所有在当前数据库中的表名

db.help()/db.tablename.help()/db.function.help()–数据库/表单/函数帮助信息

2.1 插入数据

命令模式db.tablename.insert({data}) or db.tablename.save({data})

e.g．

> usermanager_db

>db.user.insert({username:"John Liu", password: "iloveyou"})

>db.user.save({username:"John Nash", password: "John123"})

2.2 删除数据

命令模式db.tablename.remove({criteria})

删除表中的所有记录

db.tablename.remove()

 清除所有的表

db.tablename.drop()

e.g.

> db.user.remove({username:"John Liu"})

>db.user.find()

{"_id" : ObjectId("5253fe5ae4ffe9b4ec265535"),"username" : "John Nash", "pass

ord" :"John123" }

2.3 更新数据

命令模式

db.tablename.update({criteria},{$set: {new value}})

.

e.g.

> db.user.update({username:"JohnNash"}, {$set:{password:"123456"}})

> db.user.find()

{ "_id" :ObjectId("5253fe5ae4ffe9b4ec265535"), "password" :"123456", "username" : "John Nash" }

2.4 查找数据

  命令模式

db.tablename.find({criteria})

.

e.g.

username小与等于长度为8：

>db.user.find({$where:"this.username.length<=8"})

username存在：

> db.user.find({username:{$exists: true}})

2.5 建立索引

   命令模式db.tablename.ensureIndex(column)

e.g.

> db.user.ensureIndex({username:1})

> db.use.getIndexes()

[ ]

> db.user.getIndexes()

[

       {

                "v" : 1,

                "key" : {

                        "_id" : 1

                },

                "ns" :"manager_db.user",

                "name" :"_id_"

       },

       {

                "v" : 1,

                "key" : {

                        "username" : 1

                },

                "ns" :"manager_db.user",

                "name" :"username_1"

       }

]

2.6删除索引

命令模式db.tablename.dropIndex(column)

e.g.

> db.user.dropIndex({username:1})

{ "nIndexesWas" : 2, "ok" : 1}

> db.user.getIndexes()

[

        {

               "v" : 1,

               "key" : {

                        "_id" : 1

               },

               "ns" : "manager_db.user",

               "name" : "_id_"

        }

]

2.7 建立唯一索引

>db.user.ensureIndex({username:1}, {unique:true})

>db.user.getIndexes()

[

        {

                "v" : 1,

                "key" : {

                        "_id" : 1

                },

                "ns" :"manager_db.user",

                "name" :"_id_"

        },

        {

                "v" : 1,

                "key" : {

                        "username" :1

                },

                "unique" : true,

                "ns" :"manager_db.user",

                "name" :"username_1"

        }

]