关于你欠缺的NoSQL中的redis和mongoDB

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前言

不知不觉已经进入NoSQL的学习来了，那么什么是NoSQL呢？NoSQL的数据分类有哪一些呢?
一、什么是NoSQL呢？

NoSQL，指的是非关系型的数据库。NoSQL有时也称作Not Only SQL的缩写，是对不同于传统的关系
型数据库的数据库管理系统的统称。
NoSQL用于超大规模数据的存储。（例如谷歌或Facebook每天为他们的用户收集万亿比特的数据）。这
些类型的数据存储不需要固定的模式，无需多余操作就可以横向扩展。

二、NoSQL的数据分类有哪一些呢？

1、键值数据库
相关产品：Redis、Riak、SimpleDB、Chordless、Scalaris、Memcached
应用：内容缓存
优点：扩展性好、灵活性好、大量写操作时性能高
缺点：无法存储结构化信息、条件查询效率较低
使用者：百度云（Redis）、GitHub（Riak）、BestBuy（Riak）、Twitter（Ridis和
Memcached）
2、列族数据库
相关产品：BigTable、HBase、Cassandra、HadoopDB、GreenPlum、PNUTS
应用：分布式数据存储与管理
优点：查找速度快、可扩展性强、容易进行分布式扩展、复杂性低
使用者：Ebay（Cassandra）、Instagram（Cassandra）、NASA（Cassandra）、
Facebook（HBase）
3、文档数据库
相关产品：MongoDB、CouchDB、ThruDB、CloudKit、Perservere、Jackrabbit
应用：存储、索引并管理面向文档的数据或者类似的半结构化数据
优点：性能好、灵活性高、复杂性低、数据结构灵活
缺点：缺乏统一的查询语言
使用者：百度云数据库（MongoDB）、SAP（MongoDB）
4、图形数据库
相关产品：Neo4J、OrientDB、InfoGrid、GraphDB
应用：大量复杂、互连接、低结构化的图结构场合，如社交网络、推荐系统等
优点：灵活性高、支持复杂的图形算法、可用于构建复杂的关系图谱
缺点：复杂性高、只能支持一定的数据规模
使用者：Adobe（Neo4J）、Cisco（Neo4J）、T-Mobile（Neo4J）

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一、在string list hash结构中，每个至少完成5个命令，包含插入 修改 删除 查询，list 和hash还需要增加遍历的操作命令

REDIS中一些常用的命令：
LPUSH/LPUSHX：LPUSH是将值插入到链表的头部，LPUSHX是检测这个链表是否存在，如果存在的话会插入头部，如果不存在会忽略这个数据
RPUSH/RPUSHX：将值插入到链表的尾部。同上，位置相反
LPOP：移除并获取链表中的第一个元素。
RPOP：移除并获取链表中最后一个元素。
LTRIM：保留指定区间内的元素。
LLEN：获取链表的长度。
LSET:用索引设置链表元素的值。
LINDEX：通过索引获取链表中的元素。
LRANGE：获取链表指定范围内的元素。

1、STRING类型

（1） 设置键值：SET用于添加键值对,值 为string类型

①127.0.0.1:6379> set key value EX 100
OK
SET key value EX 秒数 / PX 毫秒数 NX/XX

②127.0.0.1:6379> SETNX key value
0

127.0.0.1:6379> SETNX key1 value
1
SETNX key value
命令在设置成功时返回 1   设置失败时返回 0 

③127.0.0.1:6379> SETEX key2 100 value
OK
SETEX key 秒数 value

④127.0.0.1:6379> PSETEX KEY3 100 VALUE
OK
PSETEX key 毫秒数 value

⑤127.0.0.1:6379> TTL KEY4
-2
⑥127.0.0.1:6379> PTTL KEY4
-2

（2） 读取键值：GET KEY_NAME

127.0.0.1:6379> SETEX KEYA 10 "HELLO CHINA"
OK
127.0.0.1:6379> GET KEYA
HELLO CHINA
、
当我们再去get键值的时候，却发现什么都没有，因为这是设置的时间为10s，这个时候已经过期了。
127.0.0.1:6379> GET KEYA

（3） 数值类型自增1：INCR KEY_NAME

127.0.0.1:6379> set mykey 20
OK
127.0.0.1:6379> incr mykey
21

（4） 数值类型自减1：DECR KEY_NAME

127.0.0.1:6379> set mykey 20
OK
127.0.0.1:6379> decr mykey
19

（5） 查看值的长度：SETRLEN KEY_NAME

127.0.0.1:6379> set key "this is my country china"
OK
127.0.0.1:6379> strlen key
24

2、List类型数据的命令操作：

(1）对列表city插入元素：Shanghai Suzhou Hangzhou

127.0.0.1:6379> lrange city 0 8
Hangzhou
Suzhou
Shanghai
tianjing
xian
chengdu
Chongqing

(2）将列表city里的头部的元素移除

127.0.0.1:6379> lpop city
Hangzhou
127.0.0.1:6379> lrange city 0 10
Suzhou
Shanghai
tianjing
xian
chengdu
chongqing
127.0.0.1:6379> 

(3）将name列表的尾部元素移除到number列表的头部
相关代码：RPOPLPUSH source destination

127.0.0.1:6379> lrange name 0 6
Mikky
Coco
Simmons
Tom
Susan
127.0.0.1:6379> rpoplpush name number
Susan
127.0.0.1:6379> lrange name 0 -1
Mikky
Coco
Simmons
Tom
127.0.0.1:6379> lrange number 0 -1
Susan
5
4
3
2
1

(4） 对一个已存在的列表插入新元素
相关代码：LPUSHX key value

127.0.0.1:6379> lrange name 0 6
Mikky
Coco
Simmons
Tom


127.0.0.1:6379> lpushx name Alice Brown
6

127.0.0.1:6379> lrange name 0 7
Brown
Alice
Mikky
Coco
Simmons
Tom

(5）查看list的值长度
相关代码：LLEN KEY_NAME

127.0.0.1:6379> llen name
6
127.0.0.1:6379> llen number
6

3、举例说明list和hash的应用场景，每个至少一个场景

List的应用场景：论坛评论、秒杀、消息队列

Hash的应用场景：java里结构化的信息存储，例如用户个人信息（姓名、性别、兴趣爱好）用hash结构存储

二、MongoDB作业

1.准备工作

1. 创建一个数据库 名字grade

MongoDB Enterprise > use grade
switched to db grade

2. 数据库中创建一个集合名字 class

MongoDB Enterprise > db.createCollection("class");
{ "ok" : 1 }

3. 集合中插入若干数据 文档格式如下
   ｛name:‘zhang’,age；10,sex:‘m’,hobby:[‘a’,‘b’,‘c’]｝
   hobby: draw sing dance basketball football pingpong computer
   

2. 查找

1、查看班级所有人信息
代码用法：DB.数据库.FIND()

MongoDB Enterprise > db.class.find();
{ "_id" : ObjectId("64a54599a1a01a01ed810f6b"), "name" : "小刚", "age" : 18, "sex" : "m", "hobby" : [ "football", "pingpong", "baskerball", "computer" ] }
{ "_id" : ObjectId("64a5459ca1a01a01ed810f6c"), "name" : "小红", "age" : 20, "sex" : "f", "hobby" : [ "draw", "sing", "baskerball" ] }
{ "_id" : ObjectId("64a545d7a1a01a01ed810f6d"), "name" : "小珍", "age" : 19, "sex" : "f", "hobby" : [ "draw", "sing", "dance", "computer" ] }
{ "_id" : ObjectId("64a5461da1a01a01ed810f6e"), "name" : "小政", "age" : 21, "sex" : "m", "hobby" : [ "sing", "basketball", "computer" ] }
{ "_id" : ObjectId("64a5463ea1a01a01ed810f6f"), "name" : "小芳", "age" : 20, "sex" : "f", "hobby" : [ "draw", "sing" ] }
{ "_id" : ObjectId("64a5466fa1a01a01ed810f70"), "name" : "小超", "age" : 21, "sex" : "m", "hobby" : [ "pingpong", "sing", "football" ] }
{ "_id" : ObjectId("64a54689a1a01a01ed810f71"), "name" : "小莱", "age" : 22, "sex" : "f", "hobby" : [ "pingpong", "dance", "football" ] }
MongoDB Enterprise > db.class.insert({name:"小猛",age:20,sex:'m',hobby:['basketball','dance','draw']})
WriteResult({ "nInserted" : 1 })

2、查看班级中年龄为18岁的学生信息

MongoDB Enterprise > db.class.find({age:18})
{ "_id" : ObjectId("64a54599a1a01a01ed810f6b"), "name" : "小刚", "age" : 18, "sex" : "m", "hobby" : [ "football", "pingpong", "baskerball", "computer" ] }
{ "_id" : ObjectId("64a54935a1a01a01ed810f78"), "name" : "小白", "age" : 18, "sex" : "f", "hobby" : [ "dance", "sing" ] }
{ "_id" : ObjectId("64a54957a1a01a01ed810f79"), "name" : "小哲", "age" : 18, "sex" : "m", "hobby" : [ "computer", "football", "basketball" ] }

3、查看年龄大于20岁的学生信息

MongoDB Enterprise > db.class.find({age:{$gt:20}})
{ "_id" : ObjectId("64a5461da1a01a01ed810f6e"), "name" : "小政", "age" : 21, "sex" : "m", "hobby" : [ "sing", "basketball", "computer" ] }
{ "_id" : ObjectId("64a5466fa1a01a01ed810f70"), "name" : "小超", "age" : 21, "sex" : "m", "hobby" : [ "pingpong", "sing", "football" ] }
{ "_id" : ObjectId("64a54689a1a01a01ed810f71"), "name" : "小莱", "age" : 22, "sex" : "f", "hobby" : [ "pingpong", "dance", "football" ] }
{ "_id" : ObjectId("64a548e4a1a01a01ed810f73"), "name" : "小刘", "age" : 21, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a5490aa1a01a01ed810f76"), "name" : "小粉", "age" : 23, "sex" : "f", "hobby" : [ "basketball", "dance", "draw" ] }

4、查看年龄在 18-21岁之间的学生信息

MongoDB Enterprise > db.class.find({age:{$gte:18,$lte:21}})
{ "_id" : ObjectId("64a54599a1a01a01ed810f6b"), "name" : "小刚", "age" : 18, "sex" : "m", "hobby" : [ "football", "pingpong", "baskerball", "computer" ] }
{ "_id" : ObjectId("64a5459ca1a01a01ed810f6c"), "name" : "小红", "age" : 20, "sex" : "f", "hobby" : [ "draw", "sing", "baskerball" ] }
{ "_id" : ObjectId("64a545d7a1a01a01ed810f6d"), "name" : "小珍", "age" : 19, "sex" : "f", "hobby" : [ "draw", "sing", "dance", "computer" ] }
{ "_id" : ObjectId("64a5461da1a01a01ed810f6e"), "name" : "小政", "age" : 21, "sex" : "m", "hobby" : [ "sing", "basketball", "computer" ] }
{ "_id" : ObjectId("64a5463ea1a01a01ed810f6f"), "name" : "小芳", "age" : 20, "sex" : "f", "hobby" : [ "draw", "sing" ] }
{ "_id" : ObjectId("64a5466fa1a01a01ed810f70"), "name" : "小超", "age" : 21, "sex" : "m", "hobby" : [ "pingpong", "sing", "football" ] }
{ "_id" : ObjectId("64a546bba1a01a01ed810f72"), "name" : "小猛", "age" : 20, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a548e4a1a01a01ed810f73"), "name" : "小刘", "age" : 21, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a548f0a1a01a01ed810f74"), "name" : "小霞", "age" : 20, "sex" : "f", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a54935a1a01a01ed810f78"), "name" : "小白", "age" : 18, "sex" : "f", "hobby" : [ "dance", "sing" ] }
{ "_id" : ObjectId("64a54957a1a01a01ed810f79"), "name" : "小哲", "age" : 18, "sex" : "m", "hobby" : [ "computer", "football", "basketball" ] }

5、找到年龄为20岁且为男生的学生

MongoDB Enterprise > db.class.find({age:20,sex:'m'})
{ "_id" : ObjectId("64a546bba1a01a01ed810f72"), "name" : "小猛", "age" : 20, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }

6、找到年龄小于20岁或者大于21岁的学生

MongoDB Enterprise > db.class.find({$or:[{age:{$lt:20}},{age:{$gt:21}}]})
{ "_id" : ObjectId("64a54599a1a01a01ed810f6b"), "name" : "小刚", "age" : 18, "sex" : "m", "hobby" : [ "football", "pingpong", "baskerball", "computer" ] }
{ "_id" : ObjectId("64a545d7a1a01a01ed810f6d"), "name" : "小珍", "age" : 19, "sex" : "f", "hobby" : [ "draw", "sing", "dance", "computer" ] }
{ "_id" : ObjectId("64a54689a1a01a01ed810f71"), "name" : "小莱", "age" : 22, "sex" : "f", "hobby" : [ "pingpong", "dance", "football" ] }
{ "_id" : ObjectId("64a548ffa1a01a01ed810f75"), "name" : "小绿", "age" : 17, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a5490aa1a01a01ed810f76"), "name" : "小粉", "age" : 23, "sex" : "f", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a54926a1a01a01ed810f77"), "name" : "小青", "age" : 17, "sex" : "m", "hobby" : [ "dance", "draw", "sing" ] }
{ "_id" : ObjectId("64a54935a1a01a01ed810f78"), "name" : "小白", "age" : 18, "sex" : "f", "hobby" : [ "dance", "sing" ] }
{ "_id" : ObjectId("64a54957a1a01a01ed810f79"), "name" : "小哲", "age" : 18, "sex" : "m", "hobby" : [ "computer", "football", "basketball" ] }

7、找到年龄是18岁或者21岁的学生

MongoDB Enterprise > db.class.find({$or:[{age:18},{age:21}]})
{ "_id" : ObjectId("64a54599a1a01a01ed810f6b"), "name" : "小刚", "age" : 18, "sex" : "m", "hobby" : [ "football", "pingpong", "baskerball", "computer" ] }
{ "_id" : ObjectId("64a5461da1a01a01ed810f6e"), "name" : "小政", "age" : 21, "sex" : "m", "hobby" : [ "sing", "basketball", "computer" ] }
{ "_id" : ObjectId("64a5466fa1a01a01ed810f70"), "name" : "小超", "age" : 21, "sex" : "m", "hobby" : [ "pingpong", "sing", "football" ] }
{ "_id" : ObjectId("64a548e4a1a01a01ed810f73"), "name" : "小刘", "age" : 21, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a54935a1a01a01ed810f78"), "name" : "小白", "age" : 18, "sex" : "f", "hobby" : [ "dance", "sing" ] }
{ "_id" : ObjectId("64a54957a1a01a01ed810f79"), "name" : "小哲", "age" : 18, "sex" : "m", "hobby" : [ "computer", "football", "basketball" ] }

8、找到兴趣爱好有两项的学生

MongoDB Enterprise > db.class.find({$where:"this.hobby.length == 2"})
{ "_id" : ObjectId("64a5463ea1a01a01ed810f6f"), "name" : "小芳", "age" : 20, "sex" : "f", "hobby" : [ "draw", "sing" ] }
{ "_id" : ObjectId("64a54935a1a01a01ed810f78"), "name" : "小白", "age" : 18, "sex" : "f", "hobby" : [ "dance", "sing" ] }

9、找到兴趣爱好有draw的学生

MongoDB Enterprise > db.class.find({hobby:'draw'})
{ "_id" : ObjectId("64a5459ca1a01a01ed810f6c"), "name" : "小红", "age" : 20, "sex" : "f", "hobby" : [ "draw", "sing", "baskerball" ] }
{ "_id" : ObjectId("64a545d7a1a01a01ed810f6d"), "name" : "小珍", "age" : 19, "sex" : "f", "hobby" : [ "draw", "sing", "dance", "computer" ] }
{ "_id" : ObjectId("64a5463ea1a01a01ed810f6f"), "name" : "小芳", "age" : 20, "sex" : "f", "hobby" : [ "draw", "sing" ] }
{ "_id" : ObjectId("64a546bba1a01a01ed810f72"), "name" : "小猛", "age" : 20, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a548e4a1a01a01ed810f73"), "name" : "小刘", "age" : 21, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a548f0a1a01a01ed810f74"), "name" : "小霞", "age" : 20, "sex" : "f", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a548ffa1a01a01ed810f75"), "name" : "小绿", "age" : 17, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a5490aa1a01a01ed810f76"), "name" : "小粉", "age" : 23, "sex" : "f", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a54926a1a01a01ed810f77"), "name" : "小青", "age" : 17, "sex" : "m", "hobby" : [ "dance", "draw", "sing" ] }

10、找到既喜欢画画又喜欢跳舞的学生

MongoDB Enterprise > db.class.find({hobby:{$all:['dance','draw']}})
{ "_id" : ObjectId("64a545d7a1a01a01ed810f6d"), "name" : "小珍", "age" : 19, "sex" : "f", "hobby" : [ "draw", "sing", "dance", "computer" ] }
{ "_id" : ObjectId("64a546bba1a01a01ed810f72"), "name" : "小猛", "age" : 20, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a548e4a1a01a01ed810f73"), "name" : "小刘", "age" : 21, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a548f0a1a01a01ed810f74"), "name" : "小霞", "age" : 20, "sex" : "f", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a548ffa1a01a01ed810f75"), "name" : "小绿", "age" : 17, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a5490aa1a01a01ed810f76"), "name" : "小粉", "age" : 23, "sex" : "f", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a54926a1a01a01ed810f77"), "name" : "小青", "age" : 17, "sex" : "m", "hobby" : [ "dance", "draw", "sing" ] }

11、统计爱好有三项的学生人数

MongoDB Enterprise > db.class.find({$where:"this.hobby.length == 3"})
{ "_id" : ObjectId("64a5459ca1a01a01ed810f6c"), "name" : "小红", "age" : 20, "sex" : "f", "hobby" : [ "draw", "sing", "baskerball" ] }
{ "_id" : ObjectId("64a5461da1a01a01ed810f6e"), "name" : "小政", "age" : 21, "sex" : "m", "hobby" : [ "sing", "basketball", "computer" ] }
{ "_id" : ObjectId("64a5466fa1a01a01ed810f70"), "name" : "小超", "age" : 21, "sex" : "m", "hobby" : [ "pingpong", "sing", "football" ] }
{ "_id" : ObjectId("64a54689a1a01a01ed810f71"), "name" : "小莱", "age" : 22, "sex" : "f", "hobby" : [ "pingpong", "dance", "football" ] }
{ "_id" : ObjectId("64a546bba1a01a01ed810f72"), "name" : "小猛", "age" : 20, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a548e4a1a01a01ed810f73"), "name" : "小刘", "age" : 21, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a548f0a1a01a01ed810f74"), "name" : "小霞", "age" : 20, "sex" : "f", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a548ffa1a01a01ed810f75"), "name" : "小绿", "age" : 17, "sex" : "m", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a5490aa1a01a01ed810f76"), "name" : "小粉", "age" : 23, "sex" : "f", "hobby" : [ "basketball", "dance", "draw" ] }
{ "_id" : ObjectId("64a54926a1a01a01ed810f77"), "name" : "小青", "age" : 17, "sex" : "m", "hobby" : [ "dance", "draw", "sing" ] }
{ "_id" : ObjectId("64a54957a1a01a01ed810f79"), "name" : "小哲", "age" : 18, "sex" : "m", "hobby" : [ "computer", "football", "basketball" ] }

12、找出本班年龄第二大的学生

MongoDB Enterprise > db.class.find({}).sort({age:-1}).skip(1).limit(1)
{ "_id" : ObjectId("64a54689a1a01a01ed810f71"), "name" : "小莱", "age" : 22, "sex" : "f", "hobby" : [ "pingpong", "dance", "football" ] }

13、查看学生的兴趣范围

MongoDB Enterprise > db.class.distinct('hobby')
[
	"baskerball",
	"computer",
	"football",
	"pingpong",
	"draw",
	"sing",
	"dance",
	"basketball"
]

14、将学生按年龄排序找到年龄最大的三个

MongoDB Enterprise > db.class.find({},{_id:0}).sort({age:-1}).limit(3)
{ "name" : "小粉", "age" : 23, "sex" : "f", "hobby" : [ "basketball", "dance", "draw" ] }
{ "name" : "小莱", "age" : 22, "sex" : "f", "hobby" : [ "pingpong", "dance", "football" ] }
{ "name" : "小政", "age" : 21, "sex" : "m", "hobby" : [ "sing", "basketball", "computer" ] }

15、删除所有 年级大于20或者小于18岁的学生

MongoDB Enterprise > db.class.deleteMany({$or:[{age:{$gt:20}},{age:{$lt:5}}]})
{ "acknowledged" : true, "deletedCount" : 5 }

增加、更新、删除、统计

1、将小红的年龄变为8岁 兴趣爱好变为 跳舞 画画

MongoDB Enterprise > db.class.update({'name':'小红'},{$set:{'age':8,'hobby':['dance','draw']}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
MongoDB Enterprise > db.class.find({'name':'小红'})
{ "_id" : ObjectId("64a5459ca1a01a01ed810f6c"), "name" : "小红", "age" : 8, "sex" : "f", "hobby" : [ "dance", "draw" ] }

2、追加小白兴趣爱好 唱歌

MongoDB Enterprise > db.class.update({'name':'小白'},{$push:{'hobby':'sing'}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

3、小哲兴趣爱好增加 吹牛 打篮球

MongoDB Enterprise > db.class.update({'name':'小哲'},{$push:{'hobby':{$each:['basketball','吹牛']}}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

4、小珍增加爱好，跑步和唱歌，但是不要和以前的重复

MongoDB Enterprise > db.class.update({'name':'小珍'},{$addToSet:{hobby:{$each:['running','sing']}}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

5、该班所有同学年龄加1

MongoDB Enterprise > db.class.update({},{$inc:{age:1}},false,true)
WriteResult({ "nMatched" : 10, "nUpserted" : 0, "nModified" : 10 })

6、删除小白的sex属性

MongoDB Enterprise > db.class.update({'name':'小白'},{$unset:{sex:0}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

7、删除小哲兴趣中的第一项

MongoDB Enterprise > db.class.update({'name':'小哲'},{$pop:{hobby:-1}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

8、将小红兴趣中的画画爱好删除

MongoDB Enterprise > db.class.update({'name':'小红'},{$pull:{hobby:'draw'}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

MongoDB Enterprise > db.class.find({'name':'小红'})
{ "_id" : ObjectId("64a5459ca1a01a01ed810f6c"), "name" : "小红", "age" : 9, "sex" : "f", "hobby" : [ "dance" ] }

3、增加分数域 score:{‘chinese’:88,‘english’:78,‘math’:98}

1、 按照性别分组统计每组人数

MongoDB Enterprise > db.class.aggregate([ { $group: { _id: "$sex", count: { $sum: 1 } } }])
{ "_id" : null, "count" : 1 }
{ "_id" : "f", "count" : 4 }
{ "_id" : "m", "count" : 5 }

2、按照姓名分组，过滤出有重名的同学

MongoDB Enterprise > db.class.aggregate([{$group:{_id:'$name',num:{$sum:1}}},{$match:{num:{$gt:1}}}])

3、统计每名男生的语文成绩

MongoDB Enterprise > db.class.aggregate([{$match:{sex:'m'}},{$project:{_id:0,name:1,'score.chinese':1}}])
{ "name" : "小刚", "score" : { "chinese" : 80 } }
{ "name" : "小猛", "score" : { "chinese" : 89 } }
{ "name" : "小绿", "score" : { "chinese" : 78 } }
{ "name" : "小青", "score" : { "chinese" : 75 } }
{ "name" : "小哲", "score" : { "Chinese" : 80 } }

4、将女生按照英语分数降序排列

MongoDB Enterprise > db.class.aggregate([{$match:{sex:'f'}},{$sort:{'score.english':-1}}])

{ "_id" : ObjectId("64a5459ca1a01a01ed810f6c"), "name" : "小红", "age" : 9, "sex" : "f", "hobby" : [ "dance" ], "score" : { "chinese" : 95, "english" : 90, "math" : 85 } }
{ "_id" : ObjectId("64a545d7a1a01a01ed810f6d"), "name" : "小珍", "age" : 20, "sex" : "f", "hobby" : [ "draw", "sing", "dance", "computer", "running" ], "score" : { "chinese" : 93, "english" : 88, "math" : 94 } }
{ "_id" : ObjectId("64a548f0a1a01a01ed810f74"), "name" : "小霞", "age" : 21, "sex" : "f", "hobby" : [ "basketball", "dance", "draw" ], "score" : { "chinese" : 92, "english" : 85, "math" : 76 } }
{ "_id" : ObjectId("64a5463ea1a01a01ed810f6f"), "name" : "小芳", "age" : 21, "sex" : "f", "hobby" : [ "draw", "sing" ], "score" : { "chinese" : 86, "english" : 80, "math" : 90 } }