MongoDB入门

MongoDB入门

1、什么是NoSQL

NoSQL是和传统的关系型数据库不同的数据库的统称。

关系型数据库的代表有MySQL，Oracle，Microsoft SQL Server。

NoSQL的代表有MongoDB，Memcached，Redis。

2、NoSQL分类

NoSQL分四类：键值存储，文档存储，图像存储，列存储。

其中，MongoDB属于文档存储，而Memcached和Redis属于内存级别的键值存储。

3、MongoDB简介

MongoDB是一个开源，高性能，并给予分布式文件存储的文档型数据库，

4、MongoDB特性

1、面向集合存储，易存储对象类型的数据
2、模式自由
3、支持动态查询
4、支持完全索引，包含内部对象
5、支持查询
6、支持复制和故障恢复
7、使用二进制数据存储，可以存储大型的对象（如图片，视频等）
8、自动处理碎片
9、支持多种语言
10、文档存储格式是BSON
11、网络访问

5、MongoDB安装

1、环境准备

系统：CentOS7

MongoDB：3.2.8

2、安装

创建一个目录，用于存放MongoDB的文件

mkdir /software/mongodb
cd /software/mongodb

使用wget下载安装包

wget http://downloads.mongodb.org/linux/mongodb-linux-x86_64-rhel62-3.2.8.tgz

使用tar解压

tar zxvf mongodb-linux-x86_64-rhel62-3.2.8.tgz

再创建一个data文件夹和一个log文件夹

mkdir /software/mongodb/mongo/data
mkdir /software/mongodb/mongo/log
chmod 777 /software/mongodb/mongo/data
chmod 777 /software/mongodb/mongo/log

在bin目录下创建一个mongodb.conf文件，编辑内容：

#数据文件目录
dbpath = /software/mongodb/mongo/data
#日志目录
logpath = /software/mongodb/mongo/log/mongodb.log
#端口
port = 27017
#后台运行
fork = true
nohttpinterface = true

在/lib/systemd/system目录下创建一个mongodb.service文件，编辑内容：

[Unit]  
Description=mongodb  
After=network.target remote-fs.target nss-lookup.target  
  
[Service]  
Type=forking  
ExecStart=/software/mongodb/mongo/bin/mongod --config /software/mongodb/mongo/bin/mongodb.conf  
ExecReload=/bin/kill -s HUP $MAINPID  
ExecStop=/software/mongodb/mongo/mongod --shutdown --config /software/mongodb/mongo/bin/mongodb.conf  
PrivateTmp=true  
  
[Install]  
WantedBy=multi-user.target

并赋予权限

chmod 754 mongodb.service

3、运行

启动mongodb服务

systemctl start mongodb.service

启动mongodb

./mongo

控制台输出

[root@iz2zeaf5jdjve80rjlsjgnz bin]# ./mongo
MongoDB shell version: 3.2.8
connecting to: test
Server has startup warnings: 
2019-12-06T09:21:36.266+0800 I CONTROL  [initandlisten] ** WARNING: You are running this process as the root user, which is not recommended.
2019-12-06T09:21:36.266+0800 I CONTROL  [initandlisten] 
2019-12-06T09:21:36.267+0800 I CONTROL  [initandlisten] 
2019-12-06T09:21:36.267+0800 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/enabled is 'always'.
2019-12-06T09:21:36.267+0800 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2019-12-06T09:21:36.267+0800 I CONTROL  [initandlisten] 
2019-12-06T09:21:36.267+0800 I CONTROL  [initandlisten] ** WARNING: /sys/kernel/mm/transparent_hugepage/defrag is 'always'.
2019-12-06T09:21:36.267+0800 I CONTROL  [initandlisten] **        We suggest setting it to 'never'
2019-12-06T09:21:36.267+0800 I CONTROL  [initandlisten] 
> 

6、MongoDB操作

1、数据库

MongoDB默认数据库是test。如果没有创建数据库，默认对test数据库进行操作。

【查看所有数据库】

> show dbs
local  0.000GB

【创建/选择数据库】

> use mydb
switched to db mydb
> show dbs
local  0.000GB
> db
mydb

创建数据库后，使用show dbs会发现没有创建的数据库，这是因为还没有往新创建的数据库里面添加数据。

添加一条数据

> db.collection.insert({"name":"rlxy93"})
WriteResult({ "nInserted" : 1 })
> show dbs
local  0.000GB
mydb   0.000GB

【查看所有集合】

插入一条数据时，如果指定的collection没有创建，那么会自动创建。

> show collections
collection

【删除数据库】

如果没有使用use命令，则默认删除test数据库，如果指定了，删除正在使用的那个数据库。

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

2、集合Collection

集合类似于关系型数据库中的表，一张表对应着MongoDB中的一个集合。

【创建集合】

db.createCollection(name, {capped: <Boolean>, autoIndexId: <Boolean>, size: <number>, max <number>} )

其中，

name：集合名

capped：是否启动集合限制

autoIndexId：是否使用_Id作为索引，默认是true

size：集合使用的存储空间大小

max：集合的最大条数，默认是无限

> db.createCollection("my_collection")
{ "ok" : 1 }

【删除集合】

删除成功返回true，删除失败返回false

> show collections
my_collection
> db.my_collection.drop()
true
> show collections

【插入数据】

insert()：将一条或多条数据插入到指定的Collection中

插入一条时，直接用{}括起来，插入多条时，需要用[]把{}的集合括起来组成一个数组

> db.createCollection("my_collection")
{ "ok" : 1 }
> db.my_collection.insert({"name":"rlxy93","address":"chongqing"})
WriteResult({ "nInserted" : 1 })
> db.my_collection.insert([{"name":"a","address":"chongqing"},{"name":"b","address":"chongqing"}])
BulkWriteResult({
        "writeErrors" : [ ],
        "writeConcernErrors" : [ ],
        "nInserted" : 2,
        "nUpserted" : 0,
        "nMatched" : 0,
        "nModified" : 0,
        "nRemoved" : 0,
        "upserted" : [ ]
})
> db.my_collection.find()
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c15f7be63bdb51ddcd6d"), "name" : "a", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6f"), "name" : "b", "address" : "chongqing" }

insertOne()：将一条数据插入到指定的Collection中

插入后，MongoDB会自动生成该条文档的一个_id

> db.my_collection.insertOne({"name":"lxy","address":"sichuan"})
{
        "acknowledged" : true,
        "insertedId" : ObjectId("5de9c2777be63bdb51ddcd70")
}
> db.my_collection.find()
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "a", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6f"), "name" : "b", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }

insertMany()：将多条数据插入到指定的Collection中

> db.my_collection.insertMany([{"name":"c","address":"chongqing"},{"name":"d","address":"chongqing"}])
{
        "acknowledged" : true,
        "insertedIds" : [
                ObjectId("5de9c3167be63bdb51ddcd71"),
                ObjectId("5de9c3167be63bdb51ddcd72")
        ]
}

【查询数据】

db.my_collection.find([query],[fields])
db.my_collection.find(...).count()
db.my_collection.find(...).limit(n)
db.my_collection.find(...).skip(n)
db.my_collection.find(...).sort(...)

其中，

query：过滤条件

fields：需要查询返回的字段

count()：统计查询到的数量

limit(n)：显示多少条数据

skip(n)：跳过多少条

sort()：排序

【查询集合的所有数据】

> db.my_collection.find()
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "a", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6f"), "name" : "b", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd71"), "name" : "c", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd72"), "name" : "d", "address" : "chongqing" }

【根据条件查询集合的数据】

> db.my_collection.find({"name":"a"})
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "a", "address" : "chongqing" }

【根据条件查询集合的数据，并返回指定字段】

要显示哪个字段，需要在第二个参数设置 字段名:1

1表示显示，0表示不显示。

> db.my_collection.find({"name":"a"},{"address":1})
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "address" : "chongqing" }

【统计查询到的数量】

> db.my_collection.find()
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "a", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6f"), "name" : "b", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd71"), "name" : "c", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd72"), "name" : "d", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c7a97be63bdb51ddcd73"), "name" : "rlxy93", "address" : "chongqing" }
> db.my_collection.find().count()
7

【显示指定条数】

> db.my_collection.find().limit(2)
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "a", "address" : "chongqing" }

【跳过指定条数】

> db.my_collection.find().skip(2)
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6f"), "name" : "b", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd71"), "name" : "c", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd72"), "name" : "d", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c7a97be63bdb51ddcd73"), "name" : "rlxy93", "address" : "chongqing" }

【按照指定字段排序】

> db.my_collection.find().sort({"name":1})
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "a", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6f"), "name" : "b", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd71"), "name" : "c", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd72"), "name" : "d", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c7a97be63bdb51ddcd73"), "name" : "rlxy93", "address" : "chongqing" }

【更新数据】

db.my_collection.updateOne( filter, update, <optional params> )
db.my_collection.updateMany( filter, update, <optional params> )
db.my_collection.replaceOne( filter, replacement, <optional params> )
db.my_collection.update( query, object[, upsert_bool, multi_bool] )

其中，

filter：过滤条件

update：替换的值

optional params：可选的值有upsert, w, wtimeout, j

update：是集成了updateOne，updateMany，replaceOne为一体的

【更新一条符合条件的数据】

如果update不加其他参数，默认只更改一行

> db.my_collection.updateOne({"name":"rlxy93"},{"$set":{"address":"sichuan"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.my_collection.find()
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "a", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6f"), "name" : "b", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd71"), "name" : "c", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd72"), "name" : "d", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c7a97be63bdb51ddcd73"), "name" : "rlxy93", "address" : "chongqing" }

【更新所有符合条件的数据】

> db.my_collection.updateMany({"name":"a"},{$set:{"address":"yongchuan"}})
{ "acknowledged" : true, "matchedCount" : 2, "modifiedCount" : 2 }
> db.my_collection.find()
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "a", "address" : "yongchuan" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6f"), "name" : "b", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd71"), "name" : "c", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd72"), "name" : "d", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c7a97be63bdb51ddcd73"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9d0f37be63bdb51ddcd74"), "name" : "a", "address" : "yongchuan" }

【替换数据】

> db.my_collection.replaceOne({"name":"a"},{"name":"replaceOne"})
{ "acknowledged" : true, "matchedCount" : 1, "modifiedCount" : 1 }
> db.my_collection.find()
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "replaceOne" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6f"), "name" : "b", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd71"), "name" : "c", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd72"), "name" : "d", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c7a97be63bdb51ddcd73"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9d0f37be63bdb51ddcd74"), "name" : "a", "address" : "yongchuan" }

【删除数据】

db.my_collection.deleteOne( filter, <optional params> )
db.my_collection.deleteMany( filter, <optional params> )
db.my_collection.remove(query)

其中，

filter：过滤条件

query：过滤条件

【删除一条数据】

> db.my_collection.find()
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "replaceOne" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6f"), "name" : "b", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd71"), "name" : "c", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd72"), "name" : "d", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c7a97be63bdb51ddcd73"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9d0f37be63bdb51ddcd74"), "name" : "a", "address" : "yongchuan" }
> db.my_collection.deleteOne({"name":"c"})
{ "acknowledged" : true, "deletedCount" : 1 }
> db.my_collection.find()
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "replaceOne" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6f"), "name" : "b", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd72"), "name" : "d", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c7a97be63bdb51ddcd73"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9d0f37be63bdb51ddcd74"), "name" : "a", "address" : "yongchuan" }

【删除多条数据】

> db.my_collection.find()
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "replaceOne" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6f"), "name" : "b", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c3167be63bdb51ddcd72"), "name" : "d", "address" : "chongqing" }
{ "_id" : ObjectId("5de9c7a97be63bdb51ddcd73"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9d0f37be63bdb51ddcd74"), "name" : "a", "address" : "yongchuan" }
> db.my_collection.deleteMany({"address":"chongqing"})
{ "acknowledged" : true, "deletedCount" : 2 }
> db.my_collection.find()
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "replaceOne" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c7a97be63bdb51ddcd73"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9d0f37be63bdb51ddcd74"), "name" : "a", "address" : "yongchuan" }

【删除多条数据】

> db.my_collection.find()
{ "_id" : ObjectId("5de9c0747be63bdb51ddcd6c"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "replaceOne" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9c7a97be63bdb51ddcd73"), "name" : "rlxy93", "address" : "sichuan" }
{ "_id" : ObjectId("5de9d0f37be63bdb51ddcd74"), "name" : "a", "address" : "yongchuan" }
> db.my_collection.remove({"name":"rlxy93"})
WriteResult({ "nRemoved" : 2 })
> db.my_collection.find()
{ "_id" : ObjectId("5de9c1a27be63bdb51ddcd6e"), "name" : "replaceOne" }
{ "_id" : ObjectId("5de9c2777be63bdb51ddcd70"), "name" : "lxy", "address" : "sichuan" }
{ "_id" : ObjectId("5de9d0f37be63bdb51ddcd74"), "name" : "a", "address" : "yongchuan" }

7、总结

通过以上笔记，能够学到NoSQL的一些概念，还有MongoDB的特点，安装等，并学会了MongoDB的基本CRUD操作。