一、MongoDB簡介
MongoDB是用c++語言開發的一款易擴展，易伸縮，高性能，開源的，schema free 的基于檔案的nosql資料庫；所謂nosql是指不僅僅是sql的意思，它擁有部分sql的特性，同時又比sql的性能和擴展要好；所謂schema free指沒有太多的約束，我們知道在關系型資料庫中有很多約束和范式，在MongoDB中就沒有，所以這里的schema free是指這個；mongodb支持海量資料，支持osx,linux,windows，solaris的32位和64位系統，基于GUN VGPL v3.0協議開源；
以上這張圖反映了MongoDB和其他資料庫的伸縮性和性能以及功能的一些比較；橫軸代表資料庫的功能，縱軸代表可伸縮性和性能；從上圖坐標系可以看到關系型資料sql server/mysql的功能是最強大，但是對于伸縮性和性能來講也是最低的；對于memcached來講它的的伸縮性和性能是最好的，因為它不需與持久化存盤資料，所有資料都在記憶體，同時它的功能也非常簡陋，所以memcached的性能是最好的，但是功能是最簡陋的；對于k/v鍵值資料庫來講，它的性能和伸縮性要略小于memcached,功能要比memcached要略多一點；對于MongoDB來講，它要比memcached的性能和伸縮性要略小，但功能比它強很多，性能同k/v資料庫不相上下，比關系型資料庫的可伸縮性和性能都要高很多，同時對于關系型資料庫的功能也相差不多；從上面的圖可以看到mongodb是性能和擴展性要優于關系型資料，同時功能上也不輸關系型資料庫多少；正是因為mongodb的這些特性，相比其他nosql，MongoDB的使用量是排在第一的；
MongoDB和關系型資料
以上這張圖主要對比了mongodb和關系型資料庫中的資料庫、表、行相關概念；在mongdb中的資料庫和關系型資料庫中的資料庫類似，都是用來存放多張表格，但在mongodb中，沒有表的概念，只有collection(對檔案的集合)；對于關系型資料庫中的行，就相當于mongodb中的document（檔案）；在關系型資料庫中多行資料組成一張表，多張表組成一個庫；而在mongodb中是多個檔案組成一個collection,多個collection組成一個庫；如下圖所示
MongoDB資料特點
1、mongodb是基于檔案的關系型資料庫，使用JSON的方式來存盤資料；
2、schema-free
3、用c++語言撰寫，支持全面的索引，不支持事務（支持原子事務，或者說當行檔案支持事務），基于記憶體映射檔案，所以支持延遲寫入，正因為這些特點，使得mongodb的性能優越；
4、支持副本機制，自動分片機制；所謂副本機制指當一個集群中的主節點掛掉以后，它能自動發現，并將其他一個從節點自動選舉提升為主節點；
5、查詢介面不支持sql，而是用JSON/Javascript表示的靈活的檔案查詢；
6、支持map/Reduce機制，它能夠將資料map以后再做reduce，支持并行處理；
7、支持根據位置查找物件；
二、MongoDB安裝
1、yum安裝
配置yum源
[root@node01 ~]# cat /etc/yum.repos.d/mongodb.repo [mongodb-org] name = MongoDB Repository baseurl = https://mirrors.aliyun.com/mongodb/yum/redhat/7/mongodb-org/4.4/x86_64/ gpgcheck = 1 enabled = 1 gpgkey = https://www.mongodb.org/static/pgp/server-4.4.asc [root@node01 ~]#
查看mogodb相關簡介
[root@node01 ~]# yum info mongodb-org
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* base: mirrors.aliyun.com
* extras: mirrors.aliyun.com
* updates: mirrors.aliyun.com
Available Packages
Name : mongodb-org
Arch : x86_64
Version : 4.4.1
Release : 1.el7
Size : 5.9 k
Repo : mongodb-org
Summary : MongoDB open source document-oriented database system (metapackage)
URL : http://www.mongodb.org
License : SSPL
Description : MongoDB is built for scalability, performance and high availability, scaling from single server
: deployments to large, complex multi-site architectures. By leveraging in-memory computing, MongoDB
: provides high performance for both reads and writes. MongoDB’s native replication and automated
: failover enable enterprise-grade reliability and operational flexibility.
:
: MongoDB is an open-source database used by companies of all sizes, across all industries and for a
: wide variety of applications. It is an agile database that allows schemas to change quickly as
: applications evolve, while still providing the functionality developers expect from traditional
: databases, such as secondary indexes, a full query language and strict consistency.
:
: MongoDB has a rich client ecosystem including hadoop integration, officially supported drivers for
: 10 programming languages and environments, as well as 40 drivers supported by the user community.
:
: MongoDB features:
: * JSON Data Model with Dynamic Schemas
: * Auto-Sharding for Horizontal Scalability
: * Built-In Replication for High Availability
: * Rich Secondary Indexes, including geospatial
: * TTL indexes
: * Text Search
: * Aggregation Framework & Native MapReduce
:
: This metapackage will install the mongo shell, import/export tools, other client utilities, server
: software, default configuration, and systemd service files.
[root@node01 ~]#
安裝mongodb-org
[root@node01 ~]# yum install mongodb-org -y Loaded plugins: fastestmirror Loading mirror speeds from cached hostfile * base: mirrors.aliyun.com * extras: mirrors.aliyun.com * updates: mirrors.aliyun.com Resolving Dependencies --> Running transaction check ---> Package mongodb-org.x86_64 0:4.4.1-1.el7 will be installed --> Processing Dependency: mongodb-org-tools = 4.4.1 for package: mongodb-org-4.4.1-1.el7.x86_64 --> Processing Dependency: mongodb-org-mongos = 4.4.1 for package: mongodb-org-4.4.1-1.el7.x86_64 ……省略部分內容…… Installed: mongodb-org.x86_64 0:4.4.1-1.el7 Dependency Installed: cyrus-sasl.x86_64 0:2.1.26-23.el7 cyrus-sasl-gssapi.x86_64 0:2.1.26-23.el7 cyrus-sasl-plain.x86_64 0:2.1.26-23.el7 mongodb-database-tools.x86_64 0:100.2.0-1 mongodb-org-database-tools-extra.x86_64 0:4.4.1-1.el7 mongodb-org-mongos.x86_64 0:4.4.1-1.el7 mongodb-org-server.x86_64 0:4.4.1-1.el7 mongodb-org-shell.x86_64 0:4.4.1-1.el7 mongodb-org-tools.x86_64 0:4.4.1-1.el7 Dependency Updated: cyrus-sasl-lib.x86_64 0:2.1.26-23.el7 Complete! [root@node01 ~]#
編輯組態檔/etc/mongod.conf將其配置為監聽在非127.0.0.1地址
啟動mongodb
[root@node01 ~]# systemctl start mongod.service [root@node01 ~]# ss -tnl State Recv-Q Send-Q Local Address:Port Peer Address:Port LISTEN 0 128 *:22 *:* LISTEN 0 100 127.0.0.1:25 *:* LISTEN 0 128 *:27017 *:* LISTEN 0 128 :::22 :::* LISTEN 0 100 ::1:25 :::* [root@node01 ~]#
提示：啟動后請確保27017埠處于監聽狀態即可；
2、下載官方二進制包，解壓安裝
官方下載地址：https://www.mongodb.com/try/download/community；
提示：選擇要下載的mongodb的版本和運行的系統平臺以及對應包的格式，然后點擊copy link復制下載鏈接地址；
[root@node02 ~]# cd /usr/local/src/ [root@node02 src]# ll total 0 [root@node02 src]# wget https://fastdl.mongodb.org/linux/mongodb-linux-x86_64-rhel70-4.4.1.tgz --2020-11-07 19:59:32-- https://fastdl.mongodb.org/linux/mongodb-linux-x86_64-rhel70-4.4.1.tgz Resolving fastdl.mongodb.org (fastdl.mongodb.org)... 13.35.121.42, 13.35.121.49, 13.35.121.114, ... Connecting to fastdl.mongodb.org (fastdl.mongodb.org)|13.35.121.42|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 71253687 (68M) [application/gzip] Saving to: ‘mongodb-linux-x86_64-rhel70-4.4.1.tgz’ 100%[======================================================================>] 71,253,687 2.00MB/s in 43s 2020-11-07 20:00:19 (1.57 MB/s) - ‘mongodb-linux-x86_64-rhel70-4.4.1.tgz’ saved [71253687/71253687] [root@node02 src]# ll total 69584 -rw-r--r-- 1 root root 71253687 Sep 8 22:55 mongodb-linux-x86_64-rhel70-4.4.1.tgz [root@node02 src]#
解壓包，并創建軟連接至/usr/local/mongodb
[root@node02 src]# ll total 69584 -rw-r--r-- 1 root root 71253687 Sep 8 22:55 mongodb-linux-x86_64-rhel70-4.4.1.tgz [root@node02 src]# tar xf mongodb-linux-x86_64-rhel70-4.4.1.tgz [root@node02 src]# ln -sv /usr/local/src/mongodb-linux-x86_64-rhel70-4.4.1 /usr/local/mongodb ‘/usr/local/mongodb’ -> ‘/usr/local/src/mongodb-linux-x86_64-rhel70-4.4.1’ [root@node02 src]# ll /usr/local/ total 0 drwxr-xr-x. 2 root root 6 Nov 5 2016 bin drwxr-xr-x. 2 root root 6 Nov 5 2016 etc drwxr-xr-x. 2 root root 6 Nov 5 2016 games drwxr-xr-x. 2 root root 6 Nov 5 2016 include drwxr-xr-x. 2 root root 6 Nov 5 2016 lib drwxr-xr-x. 2 root root 6 Nov 5 2016 lib64 drwxr-xr-x. 2 root root 6 Nov 5 2016 libexec lrwxrwxrwx 1 root root 48 Nov 7 20:03 mongodb -> /usr/local/src/mongodb-linux-x86_64-rhel70-4.4.1 drwxr-xr-x. 2 root root 6 Nov 5 2016 sbin drwxr-xr-x. 5 root root 49 Sep 15 20:33 share drwxr-xr-x. 3 root root 92 Nov 7 20:03 src [root@node02 src]#
將/usr/local/mongodb/bin/*軟連接至/usr/bin/
[root@node02 src]# ln -sv /usr/local/mongodb/bin/* /usr/bin/ ‘/usr/bin/install_compass’ -> ‘/usr/local/mongodb/bin/install_compass’ ‘/usr/bin/mongo’ -> ‘/usr/local/mongodb/bin/mongo’ ‘/usr/bin/mongod’ -> ‘/usr/local/mongodb/bin/mongod’ ‘/usr/bin/mongos’ -> ‘/usr/local/mongodb/bin/mongos’ [root@node02 src]# mongo mongo mongod mongos [root@node02 src]# mongo
啟動mongodb
[root@node02 src]# mkdir -p /var/lib/mongo [root@node02 src]# mkdir -p /var/log/mongodb/ [root@node02 src]# groupadd -g 995 mongod [root@node02 src]# useradd -u 996 -g mongod mongod [root@node02 src]# mongod --dbpath=/var/lib/mongo/ --logpath=/var/log/mongodb/mongod.log --bind_ip=0.0.0.0 --port=27017 --logappend --fork about to fork child process, waiting until server is ready for connections. forked process: 1594 child process started successfully, parent exiting [root@node02 src]# ss -tnl State Recv-Q Send-Q Local Address:Port Peer Address:Port LISTEN 0 128 *:22 *:* LISTEN 0 100 127.0.0.1:25 *:* LISTEN 0 128 *:27017 *:* LISTEN 0 128 :::22 :::* LISTEN 0 100 ::1:25 :::* [root@node02 src]# ps axu |grep mongod root 1594 4.8 3.8 1555604 72740 ? Sl 20:33 0:01 mongod --dbpath=/var/lib/mongo/ --logpath=/var/log/mongodb/mongod.log --bind_ip=0.0.0.0 --port=27017 --logappend --fork root 1634 0.0 0.0 112812 972 pts/0 R+ 20:34 0:00 grep --color=auto mongod [root@node02 src]#
提示：這種方式是用root用戶啟動；
用mongod用戶啟動
[root@node02 src]# mongod --shutdown --dbpath=/var/lib/mongo/ --logpath=/var/log/mongodb/mongod.log --bind_ip=0.0.0.0 --port=27017 --logappend --fork killing process with pid: 1594 [root@node02 src]# ss -tnl State Recv-Q Send-Q Local Address:Port Peer Address:Port LISTEN 0 128 *:22 *:* LISTEN 0 100 127.0.0.1:25 *:* LISTEN 0 128 :::22 :::* LISTEN 0 100 ::1:25 :::* [root@node02 src]# chown -R mongod.mongod /var/log/mongodb/ [root@node02 src]# chown -R mongod.mongod /var/lib/mongo/ [root@node02 src]# su - mongod [mongod@node02 ~]$ mongod --dbpath=/var/lib/mongo/ --logpath=/var/log/mongodb/mongod.log --bind_ip=0.0.0.0 --port=27017 --logappend --fork about to fork child process, waiting until server is ready for connections. forked process: 1697 child process started successfully, parent exiting [mongod@node02 ~]$ ss -tnl State Recv-Q Send-Q Local Address:Port Peer Address:Port LISTEN 0 128 *:22 *:* LISTEN 0 100 127.0.0.1:25 *:* LISTEN 0 128 *:27017 *:* LISTEN 0 128 :::22 :::* LISTEN 0 100 ::1:25 :::* [mongod@node02 ~]$ ps aux |grep mongod root 1671 0.0 0.1 191836 2340 pts/0 S 20:37 0:00 su - mongod mongod 1672 0.1 0.1 115940 2652 pts/0 S 20:37 0:00 -bash mongod 1697 6.3 3.7 1555916 69368 ? Sl 20:37 0:00 mongod --dbpath=/var/lib/mongo/ --logpath=/var/log/mongodb/mongod.log --bind_ip=0.0.0.0 --port=27017 --logappend --fork mongod 1738 0.0 0.1 155436 1868 pts/0 R+ 20:37 0:00 ps aux mongod 1739 0.0 0.0 112812 972 pts/0 S+ 20:37 0:00 grep --color=auto mongod [mongod@node02 ~]$
提示：關閉mongodb 使用--shutdown選項即可；
mongod 相關引數說明
--dbpath：用于指定存放資料的目錄;
--logpath:用于指定日志檔案;
--bind_ip：指定監聽的ip地址，0.0.0.0表示監聽本機所有可用地址；
--port：用于指定監聽的埠，mongodb默認是監聽27017；
--logappend：指定日志以追加的方式寫入日志檔案
--fork：指定運行為后臺；
--shutdown：指定關閉mongodb;
提供組態檔方式啟動
[mongod@node02 ~]$ cat /etc/mongod.conf dbpath=/var/lib/mongo/ logpath=/var/log/mongodb/mongod.log logappend=1 port=27017 bind_ip=0.0.0.0 fork=1
使用組態檔啟動mongodb
[mongod@node02 ~]$ mongod -f /etc/mongod.conf about to fork child process, waiting until server is ready for connections. forked process: 2050 child process started successfully, parent exiting [mongod@node02 ~]$ ss -tnl State Recv-Q Send-Q Local Address:Port Peer Address:Port LISTEN 0 128 *:22 *:* LISTEN 0 100 127.0.0.1:25 *:* LISTEN 0 128 *:27017 *:* LISTEN 0 128 :::22 :::* LISTEN 0 100 ::1:25 :::* [mongod@node02 ~]$
使用組態檔關閉mongodb
[mongod@node02 ~]$ mongod -f /etc/mongod.conf --shutdown killing process with pid: 2050 [mongod@node02 ~]$ ss -tnl State Recv-Q Send-Q Local Address:Port Peer Address:Port LISTEN 0 128 *:22 *:* LISTEN 0 100 127.0.0.1:25 *:* LISTEN 0 128 :::22 :::* LISTEN 0 100 ::1:25 :::* [mongod@node02 ~]$
以yaml格式提供組態檔，然后使用其組態檔啟動mongodb
[mongod@node02 ~]$ cat /etc/mongod.conf
systemLog:
destination: file
logAppend: true
path: /var/log/mongodb/mongod.log
storage:
dbPath: /var/lib/mongo
journal:
enabled: true
processManagement:
fork: true
net:
port: 27017
bindIp: 0.0.0.0
[mongod@node02 ~]$ ss -tnl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:22 *:*
LISTEN 0 100 127.0.0.1:25 *:*
LISTEN 0 128 :::22 :::*
LISTEN 0 100 ::1:25 :::*
[mongod@node02 ~]$ mongod -f /etc/mongod.conf
about to fork child process, waiting until server is ready for connections.
forked process: 2166
child process started successfully, parent exiting
[mongod@node02 ~]$ ss -tnl
State Recv-Q Send-Q Local Address:Port Peer Address:Port
LISTEN 0 128 *:22 *:*
LISTEN 0 100 127.0.0.1:25 *:*
LISTEN 0 128 *:27017 *:*
LISTEN 0 128 :::22 :::*
LISTEN 0 100 ::1:25 :::*
[mongod@node02 ~]$
到此，mongodb的安裝配置啟動就完成了；
三、MongoDB基礎使用
使用mongo工具連接mongodb
[root@node02 ~]# mongo --host node01
MongoDB shell version v4.4.1
connecting to: mongodb://node01:27017/?compressors=disabled&gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("ecf71c30-5113-4492-bcae-46f2d781ae59") }
MongoDB server version: 4.4.1
---
The server generated these startup warnings when booting:
2020-11-07T20:18:51.467+08:00: ***** SERVER RESTARTED *****
2020-11-07T20:18:52.481+08:00: Access control is not enabled for the database. Read and write access to data and configuration is unrestricted
2020-11-07T20:18:52.481+08:00: /sys/kernel/mm/transparent_hugepage/enabled is 'always'. We suggest setting it to 'never'
2020-11-07T20:18:52.481+08:00: /sys/kernel/mm/transparent_hugepage/defrag is 'always'. We suggest setting it to 'never'
---
---
Enable MongoDB's free cloud-based monitoring service, which will then receive and display
metrics about your deployment (disk utilization, CPU, operation statistics, etc).
The monitoring data will be available on a MongoDB website with a unique URL accessible to you
and anyone you share the URL with. MongoDB may use this information to make product
improvements and to suggest MongoDB products and deployment options to you.
To enable free monitoring, run the following command: db.enableFreeMonitoring()
To permanently disable this reminder, run the following command: db.disableFreeMonitoring()
---
>
查看幫助
> 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.mycoll.find() list objects in collection mycoll
db.mycoll.find( { a : 1 } ) list objects in mycoll 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
>
提示：db.help()是查看有關db相關操作的命令，db.mycoll.help()是查看collection相關操作的命令；
查看資料庫串列
> show dbs admin 0.000GB config 0.000GB local 0.000GB > show databases; admin 0.000GB config 0.000GB local 0.000GB >
查看當前庫下的collections
> show collections > show tables >
提示：這里沒有顯示表示當前庫沒有collection；collection是多個檔案的集合，相當于mysql中的表的概念；
切換庫
> show dbs admin 0.000GB config 0.000GB local 0.000GB > use local switched to db local > show collections startup_log >
提示：切換庫，再次查看collection，就能看到local庫下有一個startup_log的collection；這里還需要說明一點，在mongodb中資料庫是不需要創建的，直接ues即可，它是采用的延時創建資料庫的方式，只要我們切換到一個資料庫時，在往collection插入資料時，它自動會創建我們use的資料庫和我們指定的collection；如下所示，我們要創建一個student資料庫，直接使用use student命令即可；
> show dbs admin 0.000GB config 0.000GB local 0.000GB > use student switched to db student > show dbs admin 0.000GB config 0.000GB local 0.000GB >
提示：我們這里use student成功，但是直接查看資料庫是看不到的，因為student中沒有collection；只有在student庫中有collection時，這個student庫才會創建，我們再使用show dbs命令就能看到student庫；
查看當前所在資料庫
> db student > db.getName() student >
查看當前資料庫狀態資訊
> db.stats()
{
"db" : "student",
"collections" : 0,
"views" : 0,
"objects" : 0,
"avgObjSize" : 0,
"dataSize" : 0,
"storageSize" : 0,
"totalSize" : 0,
"indexes" : 0,
"indexSize" : 0,
"scaleFactor" : 1,
"fileSize" : 0,
"fsUsedSize" : 0,
"fsTotalSize" : 0,
"ok" : 1
}
>
提示：使用db.stats()命令能夠清楚的看到，當前資料庫的名稱，collections的數量，資料庫大小，存盤大小，索引等等資訊；
查看mongodb的版本號
> db.version() 4.4.1 >
查看mongodb服務器狀態
> db.serverStatus()
查看當前資料庫的連接機器地址
> db.getMongo() connection to node01:27017 >
查看當前資料庫下的所有collection名稱串列
> db.getCollectionNames() [ ] > show dbs admin 0.000GB config 0.000GB local 0.000GB > use config switched to db config > db.getCollectionNames() [ "system.sessions" ] >
創建collection
> use student
switched to db student
> db.stats()
{
"db" : "student",
"collections" : 0,
"views" : 0,
"objects" : 0,
"avgObjSize" : 0,
"dataSize" : 0,
"storageSize" : 0,
"totalSize" : 0,
"indexes" : 0,
"indexSize" : 0,
"scaleFactor" : 1,
"fileSize" : 0,
"fsUsedSize" : 0,
"fsTotalSize" : 0,
"ok" : 1
}
> db.student_info.insert({name: "tom",age: "22",gender: "nan"})
WriteResult({ "nInserted" : 1 })
> show dbs
admin 0.000GB
config 0.000GB
local 0.000GB
student 0.000GB
> show collections
student_info
> db.stats()
{
"db" : "student",
"collections" : 1,
"views" : 0,
"objects" : 1,
"avgObjSize" : 64,
"dataSize" : 64,
"storageSize" : 20480,
"indexes" : 1,
"indexSize" : 20480,
"totalSize" : 40960,
"scaleFactor" : 1,
"fsUsedSize" : 1977794560,
"fsTotalSize" : 52046860288,
"ok" : 1
}
>
提示：創建collection和創建資料庫類似，它都是采用延時創建的方法，我們只需要往對應的collection中插入檔案資料，它自動會給我們生成對應的collection；這里還需要說明一點在mongodb中，向collection中插入檔案資料時，是任意插入的，這就是mongodb和mysql關系型資料不一樣的點，因為mongodb有schema free的特點，它不受欄位的多少約束；如下
> db.student_info.insert({name: "jerry",age: "26"})
WriteResult({ "nInserted" : 1 })
> db.student_info.insert({name: "xiaoming",age: "24",gender: "M",student_id: "003",score: "84"})
WriteResult({ "nInserted" : 1 })
> db.student_info.insert({name: "xiaohong",age: "34",gender: "nv",student_id: "004",score: "44"})
WriteResult({ "nInserted" : 1 })
> db.student_info.insert({name: "zhangsan",age: "90",gender: "M",student_id: "005",score: "94"})
WriteResult({ "nInserted" : 1 })
>
查看collection的狀態資訊
> db.student_info.stats()
提示：這里顯示的內容過多，就省略了輸出的資訊；
查看collection中的檔案資訊
> db.student_info.find()
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : "22", "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "gender" : "M", "student_id" : "003", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "gender" : "nv", "student_id" : "004", "score" : "44" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
>
以美觀方式顯示查詢的檔案內容
> db.student_info.find({name:"tom"}).pretty()
{
"_id" : ObjectId("5fa6c308391624ebd5fc6bbc"),
"name" : "tom",
"age" : "22",
"gender" : "nan"
}
>
統計對應collection中有多少條檔案
> db.student_info.find().count() 5 >
查詢collection中資料的原始大小
> db.student_info.dataSize() 418 >
查詢collection中索引資料的原始大小
> db.student_info.totalIndexSize() 36864 >
查詢collection中索引加資料壓縮存盤之后的大小
> db.student_info.totalSize() 73728 >
查詢collection中資料壓縮存盤大小
> db.student_info.storageSize() 36864 >
find()高級用法
比較操作：
$gt，大于;語法格式：find({field: {$gt: value}})
$gte，大于等于；
$lt，小于；
$lte，小于等于；
$ne，不等于；如果要查詢某個欄位等于某個值，其語法格式為find({field: value})即可；
> db.student_info.find({age: {$gt: "30"}})
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "gender" : "nv", "student_id" : "004", "score" : "44" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
>
提示：以上查詢是以age欄位大于30為查詢條件；
$in，語法格式：find({field:{$in: [value，value,...]}})，表示查詢某個欄位的值在指定串列范圍的檔案
$nin，查詢指定欄位不在指定串列范圍的檔案，語法同$in相同
> db.student_info.find({age: {$in: ['22','24','26']}})
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : "22", "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "gender" : "M", "student_id" : "003", "score" : "84" }
> db.student_info.find({age: {$nin: ['22','24','26']}})
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "gender" : "nv", "student_id" : "004", "score" : "44" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
>
提示：我這里之所以數字要加引號，是因為我在創建檔案時加了引號，mongodb把它識別成字串了；正常情況數字不用加引號，是可以直接查詢的；
組合條件：
邏輯運算：
$or：或運算，語法格式：find({$or:[{<expression>},...]})
$and：與運算
$not：非運算
$nor：反運算：回傳不符合指定條件的所有檔案
> db.student_info.find({$or: [{age:{$gt:'22'}},{age:{$lt:'90'}}]})
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : "22", "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "gender" : "M", "student_id" : "003", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "gender" : "nv", "student_id" : "004", "score" : "44" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
> db.student_info.find({$and: [{age:{$gt:'22'}},{age:{$lt:'90'}}]})
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "gender" : "M", "student_id" : "003", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "gender" : "nv", "student_id" : "004", "score" : "44" }
>
元素查詢：根據指定檔案的欄位是否存在進行查詢
$exists：語法格式find({field:{$exists:<boolean>}})
> db.student_info.find({score:{$exists:true}})
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "gender" : "M", "student_id" : "003", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "gender" : "nv", "student_id" : "004", "score" : "44" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
> db.student_info.find({score:{$exists:0}})
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : "22", "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
>
提示：boolean運算式可以是true或者false；也可以是1或者0；
$type：回傳指定欄位的值的型別為指定型別的檔案，語法格式：find({field:<BSON type>})
> db.student_info.find({score:{$type:1}})
> db.student_info.find({score:{$type:2}})
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "gender" : "M", "student_id" : "003", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "gender" : "nv", "student_id" : "004", "score" : "44" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
>
提示：BSON type是對應型別的數字標識，比如double對應1，string對應2；如下圖
更新操作：語法格式db.mycoll.update(query)
$set：修改指定欄位的值為新指定的值：語法格式update({field: value},{$set:{field:new_value}})
> db.student_info.find()
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : "22", "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "gender" : "M", "student_id" : "003", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "gender" : "nv", "student_id" : "004", "score" : "44" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
> db.student_info.update({name:"tom"},{$set:{age:25}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.student_info.find()
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : 25, "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "gender" : "M", "student_id" : "003", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "gender" : "nv", "student_id" : "004", "score" : "44" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
>
$unset：洗掉指定欄位：語法格式：update({field:value},{$unset:{field1:value,field2:value,...}})
> db.student_info.update({name:"xiaoming"},{$unset:{gender:"nan"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.student_info.find()
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : 25, "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "student_id" : "003", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "gender" : "nv", "student_id" : "004", "score" : "44" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
> db.student_info.update({name:"xiaoming"},{$unset:{gender:"nan",student_id:"003"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.student_info.find()
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : 25, "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "gender" : "nv", "student_id" : "004", "score" : "44" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
>
$rename：更改欄位名，語法格式update({field:value},{$rename:{oldname1:newname,oldname2:newname,...}})
> db.student_info.find()
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : 25, "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "gender" : "nv", "student_id" : "004", "score" : "44" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
> db.student_info.update({name:"xiaohong"},{$rename:{gender:"xingbie",student_id:"xuehao"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.student_info.find()
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : 25, "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "score" : "44", "xingbie" : "nv", "xuehao" : "004" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
>
提示：當前面的條件為{},表示更新檔案全部欄位名稱；
洗掉操作：語法格式：db.mycoll.remove(<query>,<justone>)
> db.student_info.find()
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : 25, "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "score" : "44", "xingbie" : "nv", "xuehao" : "004" }
{ "_id" : ObjectId("5fa6c89c391624ebd5fc6bc0"), "name" : "zhangsan", "age" : "90", "gender" : "M", "student_id" : "005", "score" : "94" }
> db.student_info.remove({name:"zhangsan"})
WriteResult({ "nRemoved" : 1 })
> db.student_info.find()
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : 25, "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : "26" }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "score" : "44", "xingbie" : "nv", "xuehao" : "004" }
> db.student_info.update({name:"jerry"},{$set:{age:25}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.student_info.find()
{ "_id" : ObjectId("5fa6c308391624ebd5fc6bbc"), "name" : "tom", "age" : 25, "gender" : "nan" }
{ "_id" : ObjectId("5fa6c597391624ebd5fc6bbd"), "name" : "jerry", "age" : 25 }
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "score" : "44", "xingbie" : "nv", "xuehao" : "004" }
> db.student_info.remove({age:25})
WriteResult({ "nRemoved" : 2 })
> db.student_info.find()
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "score" : "44", "xingbie" : "nv", "xuehao" : "004" }
>
提示：默是洗掉符合指定條件的所有檔案，我們可以在后面寫一個數字，來指定洗掉匹配條件的檔案數量
> db.student_info.find()
{ "_id" : ObjectId("5fa6c84b391624ebd5fc6bbe"), "name" : "xiaoming", "age" : "24", "score" : "84" }
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "score" : "44", "xingbie" : "nv", "xuehao" : "004" }
> db.student_info.remove({age:{$type:2}},1)
WriteResult({ "nRemoved" : 1 })
> db.student_info.find()
{ "_id" : ObjectId("5fa6c877391624ebd5fc6bbf"), "name" : "xiaohong", "age" : "34", "score" : "44", "xingbie" : "nv", "xuehao" : "004" }
>
洗掉collection
> db.student_info.drop() true > show collections >
洗掉資料庫
> db.getName()
student
> db.dropDatabase()
{ "dropped" : "student", "ok" : 1 }
> show dbs
admin 0.000GB
config 0.000GB
local 0.000GB
>
提示：一般洗掉資料庫要切換到對應的資料庫下執行db.dropDatabase()；
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