MongoDB学习——初探

MongoDB 初探

简介

MongoDB是开源的基于文档的数据库系统，存储基于BSON（类似JSON）的文档，支持复杂的数据结构，支持全部的索引，且提供了强大的查询接口，提供了良好的水平扩展支持，可以存储海量数据，被认为是mysql的替代品。

安装

MongoDB有针对CentOS的rpm安装包

加入源，由于是10gen开发的，所以源名为10gen，

# vi /etc/yum.repos.d/10gen.repo，加入：

[10gen]
name=10gen Repository
baseurl=http://downloads-distro.mongodb.org/repo/redhat/os/i686
gpgcheck=0
enabled=1

用yum安装：

# yum install mongo-10gen mongo-10gen-server

基本操作

启动/停止/重启

安装好后，保持默认的配置，就可以用其自带脚本启动，停止了

# service mongod start

MongoDB自带了一个webconsole，默认端口：28017

在浏览器中输入

http://localhost:28017/

即可看到目前的状态

 

基本的CRUD操作

MongoDB自带了命令行客户端

$ mongo
MongoDB shell version: 2.4.5
connecting to: test
Server has startup warnings:
Mon Jul 29 14:09:40.625 [initandlisten]
Mon Jul 29 14:09:40.625 [initandlisten] ** NOTE: This is a 32 bit MongoDB binary.
Mon Jul 29 14:09:40.625 [initandlisten] ** 32 bit builds are limited to less than 2GB of data (or less with --journal).
Mon Jul 29 14:09:40.625 [initandlisten] ** Note that journaling defaults to off for 32 bit and is currently off.
Mon Jul 29 14:09:40.625 [initandlisten] ** See http://dochub.mongodb.org/core/32bit
Mon Jul 29 14:09:40.626 [initandlisten]

默认链接到test数据库

向集合user里加一条记录，注意MongoDB里面的集合可以认为是mysql的表

> db.user.insert({'name':'jack','age':20})

 查询刚刚插入的记录：

> db.user.find({'name':'jack'})
{ "_id" : ObjectId("51f717e2214a69388a1d7424"), "name" : "jack", "age" : 20 }
>

 更新记录：

全部更新

第一个参数是条件，第二个是值

> db.user.update({"name":"jack"}, { "name" : "jack", "age" : 50, "address" : { "country" : "CN", "city" : "HongKong" }, "fav" : [ "apple", "banana" ] })
>
> db.user.find({"name":"jack"})
{ "_id" : ObjectId("51f717e2214a69388a1d7424"), "name" : "jack", "age" : 50, "address" : { "country" : "CN", "city" : "HongKong" }, "fav" : [ "apple", "banana" ] }

部分更新

$set如果存在该字段，则修改，如果不存在则增加

$inc，指定字段递增

> db.user.update({"name":"jack"}, {$inc:{"age":1}})
>
> db.user.find({"name":"jack"})
{ "_id" : ObjectId("51f730c604f4bacbc87f67f2"), "name" : "jack", "age" : 54, "address" : { "country" : "CN", "city" : "Macao" }, "fav" : [ "apple", "banana" ], "email" : "[email protected]" }
>
> db.user.update({"name":"jack"}, {$set:{"gender":"male"}})
>
> db.user.find({"name":"jack"})
{ "_id" : ObjectId("51f730c604f4bacbc87f67f2"), "address" : { "country" : "CN", "city" : "Macao" }, "age" : 54, "email" : "[email protected]", "fav" : [ "apple", "banana" ], "gender" : "male", "name" : "jack" }
> 

InsertOrUpdate

指定第三个参数为true

> db.user.update({"name":"hellen"}, {"name":"hellen", "age":19}, true)
>
> db.user.find()
{ "_id" : ObjectId("51f7312b04f4bacbc87f67f3"), "name" : "allen", "age" : 20, "address" : { "country" : "US", "city" : "NewYork" }, "email" : "[email protected]" }
{ "_id" : ObjectId("51f730c604f4bacbc87f67f2"), "address" : { "country" : "CN", "city" : "Macao" }, "age" : 54, "email" : "[email protected]", "fav" : [ "apple", "banana" ], "gender" : "male", "name" : "jack" }
{ "_id" : ObjectId("51f740fb2c6c3ba0d71db410"), "name" : "hellen", "age" : 19 }

删除记录：

> db.user.remove({"name":"jack"})
>
> db.user.find({})
>

 注意：remove如果不加条件会删除所有的记录，且不能恢复。

find不加条件查询所有的记录