day--86（MongoDB数据库）

　　　　　　　　　　　　　　　　mongodb数据库基本操作指令

ps：mongodb中的 文档，集合的概念（和mysql中的表对比理解）：

集合（mongodb）--相当于mysql中的表
文档（mongodb）--相当于mysql中的行

一：mongodb数据库操作

  use blog  #切换到这个数据库，如果没有则创建，有则切换
  switched to db blog
  > show dbs  #显示所有的数据库
  admin   0.000GB
  blog    0.000GB
  config  0.000GB
  local   0.000GB
  > db.article.insert({"title":"python"})  #db代表当前切换的数据库blog
  WriteResult({ "nInserted" : 1 })
  > db.userinfo.insert({"name":"tom"}) #往数据库添加集合（mysql中叫做表，mongodb中叫做 集合）
  WriteResult({ "nInserted" : 1 })
  > show tables;  #显示所有的集合
  article
  userinfo
  > show dbs
  admin   0.000GB
  blog    0.000GB
  config  0.000GB
  local   0.000GB
 
  > db.dropDatabase()   #删除这个数据库
  { "dropped" : "blog", "ok" : 1 }
  > show dbs
  admin   0.000GB
  config  0.000GB
  local   0.000GB

二：mongodb数据库的集合操作（mysql中称之为：表）

  > use blog
  switched to db blog
  > db.article.insert({"name":"c++"})
  WriteResult({ "nInserted" : 1 })
  > db.article.insert({"name":"linux"})
  WriteResult({ "nInserted" : 1 })
  > show tables;  #显示当前所有的集合
  article
  > db.article.drop() #删除这个文档
  true   #显示已经删除
  > show tables  #再显示，已经没有了，所以没有打印出来

三：文档操作（相当于mysql中的行）

　　1：添加文档

01:没有指定_id则默认ObjectId,_id不能重复，且在插入后不可变

:插入单条文档
cmd界面操作：
小技巧： ^ 放在cmd界面一行的前面和最后面，用来换行，因此才会，在文档结束的时     候，再加上^就会 结束换行
       > user0={^
        ... "name":"tom",
        ... "age":10,
        ... "hobbies":["musice","read","dancing"],
        ... "addr":{"countye":"China","city":"BJ"}
        ... ^}
        2019-03-05T20:36:20.263+0800 E QUERY    [js] Synt
        > db.test.insert(user0)
        WriteResult({ "nInserted" : 1 })
        > db.test.find()
        { "_id" : ObjectId("5c7e6d52253ec476879e656a") }

：插入多条

user1={
            "_id":1,
            "name":"alex",
            "age":10,
            'hobbies':['music','read','dancing'],
            'addr':{
                'country':'China',
                'city':'weifang'
            }
        }
 
        user2={
            "_id":2,
            "name":"wupeiqi",
            "age":20,
            'hobbies':['music','read','run'],
            'addr':{
                'country':'China',
                'city':'hebei'
            }
        }
 
        user3={
            "_id":3,
            "name":"yuanhao",
            "age":30,
            'hobbies':['music','drink'],
            'addr':{
                'country':'China',
                'city':'heibei'
            }
        }
 
        user4={
            "_id":4,
            "name":"jingliyang",
            "age":40,
            'hobbies':['music','read','dancing','tea'],
            'addr':{
                'country':'China',
                'city':'BJ'
            }
        }
 
        user5={
            "_id":5,
            "name":"jinxin",
            "age":50,
            'hobbies':['music','read',],
            'addr':{
                'country':'China',
                'city':'henan'
            }
        }
 
        >db.user.insertMany([user1,user2,user3,user4,user5])
 
        > db.user.find()
        { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
        { "_id" : 2, "name" : "wupeiqi", "age" : 20, "hobbies" : [ "music", "read", "run" ], "addr" : { "country" : "China", "city" : "hebei" } }
        { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
        { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
        { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
        >

2:查看文档

　　001：比较运算

　　

# SQL：=,!=,>,<,>=,<=
# MongoDB：{key:value}代表什么等于什么,"$ne","$gt","$lt","gte","lte",
  其中"$ne"能用于所有数据类型
 
#1、select * from db1.user where name = "alex"; #(mysql)
   > db.user.find({"name":"alex"})
   { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
 
#2、select * from db1.user where name != "alex"; #(mysql)
   > db.user.find({"name":{"$ne":"alex"}})
   { "_id" : 2, "name" : "wupeiqi", "age" : 20, "hobbies" : [ "music", "read", "run" ], "addr" : { "country" : "China", "city" : "hebei" } }
   { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
   { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
   { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
 
#3、select * from db1.user where id > 2; #(mysql)
    > db.user.find({'_id':{'$gt':2}})
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    >
 
#4、select * from db1.user where id < 3; #(mysql)
    > db.user.find({'_id':{"$gte":2,}})
    { "_id" : 2, "name" : "wupeiqi", "age" : 20, "hobbies" : [ "music", "read", "run" ], "addr" : { "country" : "China", "city" : "hebei" } }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    >
#5、select * from db1.user where id <= 2; #(mysql)
    > db.user.find({"_id":{"$lte":2}})
    { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
    { "_id" : 2, "name" : "wupeiqi", "age" : 20, "hobbies" : [ "music", "read", "run" ], "addr" : { "country" : "China", "city" : "hebei" } }
    >

　　002：逻辑运算

　　

# MySQL：and，or，not
# MongoDB：字典中逗号分隔的多个条件是and关系，"$or"的条件放到[]内,"$not"
----------------理解小概念-------------
ps：db：表示当前的数据库，user表示当前数据库下的这个集合（表）
 
#1、select * from db1.user where id >= 2 and id < 4;
    > db.user.find({"_id":{"$gt":2,"$lt":4}})  # 意思是：找到当前数据库下的user集合下的数据
 结果：{ "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    >
 
#2、select * from db1.user where id >= 2 and age < 40;
    > db.user.find({"_id":{"$gte":2},"age":{"$lt":40}})
结果： { "_id" : 2, "name" : "wupeiqi", "age" : 20, "hobbies" : [ "music", "read", "run" ], "addr" : { "country" : "China", "city" : "hebei" } }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    >
 
#3、select * from db1.user where id >= 5 or name = "alex";
    db.user.find({
        "$or":[
            {'_id':{"$gte":5}},
            {"name":"alex"}
            ]
    })
 
结果： >{ "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
    { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
 
#4、select * from db1.user where id >= 5 or name = "alex";
    > db.user.find({"_id":{"$mod":[2,1]}})  #将id的值除2取1，（取奇数）
结果：{ "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    >
#5、取反：
    db.user.find({'_id':{"$not":{"$mod":[2,1]}}}) #拿到所有不是奇数的数据

003：成员运算

# mysql： in，not in
#mongodb: "$in","$nin"
 
#1、select * from db1.user where age in (20,30,31);
    > db.user.find({"age":{"$in":[20,30,31]}})  #取出年龄在这个集合之中的数据
    { "_id" : 2, "name" : "wupeiqi", "age" : 20, "hobbies" : [ "music", "read", "run" ], "addr" : { "country" : "China", "city" : "hebei" } }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    >
 
#2、select * from db1.user where name not in ('alex','yuanhao');
    > db.user.find({"name":{"$nin":["alex","yuanhao"]}})  #取出姓名不在这个集合中的数据
    { "_id" : 2, "name" : "wupeiqi", "age" : 20, "hobbies" : [ "music", "read", "run" ], "addr" : { "country" : "China", "city" : "hebei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" }}
    { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    >

004：正则匹配

# SQL: regexp 正则
# MongoDB: /正则表达/i
#1、select * from db1.user where name regexp '^j.*?(g|n)$';
    > db.user.find({'name':/^j.*?(g|n)$/i})
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    >

　　005:取指定字段

#1、select name,age from db1.user where id=3;
    > db.user.find({"_id":3},{'name':1,"age":1})  #取id为3的数据，并且显示姓名和年龄，1 代表显示，0 代表不显示
    { "_id" : 3, "name" : "yuanhao", "age" : 30 }
    >
 
#2:查询出id为3的数据，并且不显示地址，其他字段默认显示，
    > db.user.find({"_id":3},{"addr":0})
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ] }
    >

006：查询数组

#1、查看有dancing爱好的人
    > db.user.find({"hobbies":"dancing"})
-->
    { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    >
 
#2、查看既有dancing爱好又有tea爱好的人
    db.user.find({
        'hobbies':{
            "$all":['dancing','tea']
            }
    })
-->
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
 
#3、查看第4个爱好为tea的人
    db.user.find({"hobbies.3":'tea'})
-->
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
 
#4、查看所有人最后两个爱好
    db.user.find({},{'hobbies':{"$slice":-2},"age":0,"_id":0,"name":0,"addr":0}) #0代表字段不显示
-->
    { "hobbies" : [ "read", "dancing" ] }
    { "hobbies" : [ "read", "run" ] }
    { "hobbies" : [ "music", "drink" ] }
    { "hobbies" : [ "dancing", "tea" ] }
    { "hobbies" : [ "music", "read" ] }
 
#5、查看所有人的第2个到第3个爱好
    db.user.find({},{'hobbies':{"$slice":[1,2]},"age":0,"_id":0,"name":0,"addr":0})
-->  #这个是时候的切片，两边都是闭区间。----〉取头，取尾
    { "hobbies" : [ "read", "dancing" ] }
    { "hobbies" : [ "read", "run" ] }
    { "hobbies" : [ "drink" ] }
    { "hobbies" : [ "read", "dancing" ] }
    { "hobbies" : [ "read" ] }

　　007:排序

# 排序: 1代表升序，-1代表降序
    db.user.find().sort({"name":1,})  #按名字的升序排列
 --〉
    > db.user.find().sort({"name":1,})
    { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 2, "name" : "wupeiqi", "age" : 20, "hobbies" : [ "music", "read", "run" ], "addr" : { "country" : "China", "city" : "hebei" } }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    >
 
    db.user.find().sort({"age":-1,'_id':1})   # 按照年龄降序排列，如果年龄一样，则按照id 升序排列
 --〉
    "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    "_id" : 2, "name" : "wupeiqi", "age" : 20, "hobbies" : [ "music", "read", "run" ], "addr" : { "country" : "China", "city" : "hebei" } }
    "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }

008：分页（limit代表取多少个document，skip代表跳过前多少个document。）

db.user.find().sort({'age':1}).limit(1).skip(2)
-->
{ "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }

　　009:查询数量

第一种方法：
> db.user.count({"age":{"$gt":30}})
---> 2
 
第二种方法：
> db.user.find({"age":{"$gt":30}}).count()
--->2

　　010:其他方法：

#1、{'key':null} 匹配key的值为null或者没有这个key
    > db.t2.insert({"a":10,"b":111})
    WriteResult({ "nInserted" : 1 })
    > db.t2.insert({"a":20})
    WriteResult({ "nInserted" : 1 })
    > db.t2.insert({"b":null})
    WriteResult({ "nInserted" : 1 })
    >
    > db.t2.find({"b":null})
    { "_id" : ObjectId("5c7f23577e39bd0c0f8fd7ba"), "a" : 20 }
    { "_id" : ObjectId("5c7f236a7e39bd0c0f8fd7bb"), "b" : null }
#2、查找所有
    db.user.find() #等同于db.user.find({})
    db.user.find().pretty()  #pretty() 格式化输出，使结果在cmd界面是换行输出的
 
#3、查找一个，与find用法一致，只是只取匹配成功的第一个
    db.user.findOne()   #取所有结果的第一个且格式化输出
    db.user.findOne({"_id":{"$gt":3}})　  #取所有结果的第一个且格式化输出

3：修改文档update

update() 方法用于更新已存在的文档。语法格式如下：
 
db.collection.update(
   <query>,
   <update>,
   {
     upsert: <boolean>,
     multi: <boolean>,
     writeConcern: <document>
   }
)
 
参数说明：对比update db1.t1 set name='EGON',sex='Male' where name='egon' and age=18;
 
query : 相当于where条件。
update : update的对象和一些更新的操作符（如$,$inc...等，相当于set后面的
upsert : 可选，默认为false，代表如果不存在update的记录不更新也不插入，设置为true代表插入。
multi : 可选，默认为false，代表只更新找到的第一条记录，设为true,代表更新找到的全部记录。
writeConcern :可选，抛出异常的级别。
 
更新操作是不可分割的：若两个更新同时发送，先到达服务器的先执行，然后执行另外一个，不会破坏文档。

　　001:覆盖更新　　

第一种方法：
    原来的数据：
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
    { "_id" : 2, "name" : "wupeiqi", "age" : 20, "hobbies" : [ "music", "read", "run" ], "addr" : { "country" : "China", "city" : "hebei" } }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
 
    更新后的数据：
    #查询年龄为20 的数据，并将这条数据替换为后面的数据，默认是替换找到的第一条数据，也可以设置multi=True，则替换所有找到的数据
    > db.user.update({"age":20},{"name":"Wxx","hobbies_count":3})
    WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
    { "_id" : 2, "name" : "Wxx", "hobbies_count" : 3 }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    >
    说明：是用{"_id":2,"name":"Wxx","hobbies_count":3}覆盖原来的记录原来的记录就不会存在了
 
第二种方法：
002：一种最简单的更新就是用一个新的文档完全替换匹配的文档。这适用于大规模式迁移的情况。例如
    var obj=db.user.findOne({"_id":2})
 
    obj.username=obj.name+'SB'
    obj.hobbies_count++
    delete obj.age
 
    db.user.update({"_id":2},obj)

　　002：局部更新

通常文档只会有一部分需要更新。可以使用原子性的更新修改器，指定对文档中的某些字段进行更新。更新修改器是种特殊的键，用来指定复杂的更新操作，
比如修改、增加后者删除设置：$set

#1:#1、update db1.user set  name="WXX" where id = 2
    > db.user.update({"_id":2},{"$set":{"name":"MMM",}})
    WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 3 }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
 
#2、没有匹配成功则新增一条{"upsert":true}  #--------
    upsert : 可选，默认为false，代表如果不存在update的记录不更新也不插入，设置为true代表插入。
 
    db.user.update({"_id":6},{"$set":{"name":"tom","age":18}},{"upsert":true})
    WriteResult({ "nMatched" : 0, "nUpserted" : 1, "nModified" : 0, "_id" : 6 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 3 }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 50, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 18, "name" : "tom" }
>
 
#3、默认只改匹配成功的第一条,{"multi":改多条}
    db.user.update({'_id':{"$gt":4}},{"$set":{"age":28}})
    -->默认第一条
    WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB" }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 28, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 18, "name" : "tom" }
 
-->multi设置可以改多条
将id大于4的文档的年龄 改为 38 ，全部匹配的都改
    > db.user.update({'_id':{"$gt":4}},{"$set":{"age":38}},{"multi":true})   # true  必须小写
    WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "China", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB" }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 38, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 38, "name" : "tom" }
 
4、修改内嵌文档，把名字为alex的人所在的地址国家改成Japan
    > db.user.update({"name":"alex"},{"$set":{"addr.country":"Japan"}})
    WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "read", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB" }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 38, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 38, "name" : "tom" }
 
#5、把名字为alex的人的第2个爱好改成eat
    > db.user.update({"name":"alex"},{"$set":{"hobbies.1":"eat"}})
    WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB" }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 38, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 38, "name" : "tom" }
    >
#6、删除alex的爱好,$unset
    > db.user.update({"name":"axle"},{"$unset":{"hobbies":""}})
    WriteResult({ "nMatched" : 0, "nUpserted" : 0, "nModified" : 0 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 10, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB" }
    { "_id" : 3, "name" : "yuanhao", "age" : 30, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 40, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 38, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 38, "name" : "tom" }

　　003:增加和减少

#1、所有人年龄增加一岁
    > db.user.update({},{"$inc":{"age":1}},{"multi":true})
    WriteResult({ "nMatched" : 6, "nUpserted" : 0, "nModified" : 6 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 11, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB", "age" : 1 }
    { "_id" : 3, "name" : "yuanhao", "age" : 31, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 41, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 39, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 39, "name" : "tom" }
 
#2、所有人年龄减少5岁
    > db.user.update({},{"$inc":{"age":-5}},{"multi":true})
    WriteResult({ "nMatched" : 6, "nUpserted" : 0, "nModified" : 6 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 6, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB", "age" : -4 }
    { "_id" : 3, "name" : "yuanhao", "age" : 26, "hobbies" : [ "music", "drink" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 36, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 34, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 34, "name" : "tom" }

4:添加删除数组内元素

　　#添加删除数组内元素：$push,$pop,$pull往数组内添加元素：$push

#1、为名字为yuanhao的人添加一个爱好read
    > db.user.update({"name":"yuanhao"},{"$push":{"hobbies":"read"}})
    WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 6, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB", "age" : -4 }
    { "_id" : 3, "name" : "yuanhao", "age" : 26, "hobbies" : [ "music", "drink", "tea", "dancing", "read" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 36, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 34, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 34, "name" : "tom" }
    >
--------------------------------------$each-------------------------------------------------------------
#2、为名字为yuanhao的人一次添加多个爱好tea，dancing
    > db.user.update({"name":"yuanhao"},{"$push":{"hobbies":{"$each":["tea","dancing"]}}})
    WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 6, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB", "age" : -4 }
    { "_id" : 3, "name" : "yuanhao", "age" : 26, "hobbies" : [ "music", "drink", "tea", "dancing" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 36, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 34, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 34, "name" : "tom" }
 
按照位置且只能从开头或结尾删除元素：$pop
#3、{"$pop":{"key":1}} 从数组末尾删除一个元素
 
    > db.user.update({"name":"yuanhao"},{"$pop":{"hobbies":1}})
    WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 6, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB", "age" : -4 }
    { "_id" : 3, "name" : "yuanhao", "age" : 26, "hobbies" : [ "music", "drink", "tea", "dancing" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 36, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 34, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 34, "name" : "tom" }
    >
#4、{"$pop":{"key":-1}} 从头部删除
 
    > db.user.update({"name":"yuanhao"},{"$pop":{"hobbies":-1}})
    WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 6, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB", "age" : -4 }
    { "_id" : 3, "name" : "yuanhao", "age" : 26, "hobbies" : [ "drink", "tea", "dancing" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 36, "hobbies" : [ "music", "read", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 34, "hobbies" : [ "music", "read" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 34, "name" : "tom" }
    >
#5、按照条件删除元素,："$pull" 把符合条件的统统删掉，而$pop只能从两端删
    > db.user.update({"addr.country":"China"},{"$pull":{"hobbies":"read"}},{"multi":true})
    WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 2 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 6, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB", "age" : -4 }
    { "_id" : 3, "name" : "yuanhao", "age" : 26, "hobbies" : [ "drink", "tea", "dancing" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 36, "hobbies" : [ "music", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 34, "hobbies" : [ "music" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 34, "name" : "tom" }

5:避免重复添加

#避免添加重复："$addToSet"
 
db.urls.insert({"_id":1,"urls":[]})  #第一条文档
 
db.urls.update({"_id":1},{"$addToSet":{"urls":'http://www.baidu.com'}}) #第二条文档
db.urls.update({"_id":1},{"$addToSet":{"urls":'http://www.baidu.com'}}) #第三条文档
db.urls.update({"_id":1},{"$addToSet":{"urls":'http://www.baidu.com'}}) #第四条文档
 
#第五条文档
db.urls.update({"_id":1},{
    "$addToSet":{
        "urls":{
        "$each":[
            'http://www.baidu.com',
            'http://www.baidu.com',
            'http://www.xxxx.com'
            ]
            }
        }
    }
)
 
查看urls集合：
> db.urls.find()
{ "_id" : 1, "urls" : {  } }
 
总结："$addToSet" 在集合中有记录的时候，由于id是唯一的，所以后面的数据都没有添加进去

6:其他：

#1、限制大小"$slice"，只留最后n个
 
    db.user.update({"_id":5},{
        "$push":{"hobbies":{
        "$each":["read",'music','dancing'],  #先往条文档添加三个hobby，再只取最后两个hobby
        "$slice":-2  # 只保留最后两个hobbies
        }
        }
    })
 
    结果是：
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 6, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB", "age" : -4 }
    { "_id" : 3, "name" : "yuanhao", "age" : 26, "hobbies" : [ "drink", "tea", "dancing" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 36, "hobbies" : [ "music", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 34, "hobbies" : [ "music", "dancing" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 34, "name" : "tom" }
 
  #2、排序The $sort element value must be either 1 or -1"
 
    db.user.update({"_id":5},{
        "$push":{"hobbies":{
        "$each":["read",'music','dancing'], # $push  往这个条文档里面添加三个hobbies，
        "$slice":-1,        # 取倒数第一个（最尾部的第一个）
        "$sort":-1          #排序：倒叙
        }
        }
    })
 
    结果：
    WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 6, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB", "age" : -4 }
    { "_id" : 3, "name" : "yuanhao", "age" : 26, "hobbies" : [ "drink", "tea", "dancing" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 36, "hobbies" : [ "music", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 34, "hobbies" : [ "dancing" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 34, "name" : "tom" }
    >
 
    #注意：不能只将"$slice"或者"$sort"与"$push"配合使用，且必须使用"$each"

4:删除文档

#1、删除多个中的第一个
    db.user.deleteOne({ 'age': 8 })
原来的数据：
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 6, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB", "age" : -4 }
    { "_id" : 3, "name" : "yuanhao", "age" : 26, "hobbies" : [ "drink", "tea", "dancing" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 36, "hobbies" : [ "music", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 5, "name" : "jinxin", "age" : 34, "hobbies" : [ "dancing" ], "addr" : { "country" : "China", "city" : "henan" } }
    { "_id" : 6, "age" : 34, "name" : "tom" }
    >
 
删除后的数据  #只删除了多个中的第一条匹配数据
    > db.user.deleteOne({"age":34})
    { "acknowledged" : true, "deletedCount" : 1 }
    > db.user.find()
    { "_id" : 1, "name" : "alex", "age" : 6, "hobbies" : [ "music", "eat", "dancing" ], "addr" : { "country" : "Japan", "city" : "weifang" } }
    { "_id" : 2, "name" : "MMM", "hobbies_count" : 4, "username" : "MMMSB", "age" : -4 }
    { "_id" : 3, "name" : "yuanhao", "age" : 26, "hobbies" : [ "drink", "tea", "dancing" ], "addr" : { "country" : "China", "city" : "heibei" } }
    { "_id" : 4, "name" : "jingliyang", "age" : 36, "hobbies" : [ "music", "dancing", "tea" ], "addr" : { "country" : "China", "city" : "BJ" } }
    { "_id" : 6, "age" : 34, "name" : "tom" }
    >
 
#3、删除全部
    > db.user.deleteMany({})
    { "acknowledged" : true, "deletedCount" : 5 }  #显示删除成功！
    > db.user.find()