一、MongoDB介绍
MongoDB是一个基于分布式文件存储的数据库。
由C++语言编写。旨在为WEB应用提供可扩展的 高性能数据存储解决方案。
MongoDB是一个介于关系型数据库和非关系数据库之间的产品，是非关系数据库当中功能最丰富，最像关系数据库的。
MongoDB支持的数据结构非常松散，是类似JSON的BJSON格式，因此可以存储比较复 杂的数据类型。Mongo最大的特点是它支持的查询语言非常强大，其语法有点类似于面向对象的查询语 言，几乎可以实现类似关系数据库单表查询的绝大部分功能，而且还支持对数据建立索引。
MongoDB数据操作基于json格式
{ "userName":"admin", "password":123456 }
二、MongoDB安装
1.MongoDB下载
2.MongoDB安装
全程点击next安装，但是这一步需要注意，这里是安装可视化组件，默认是选择状态，这里需 要取消选中，否则在安装的过程中要下载可视化组件，比较慢，甚至有时候会报错：
3.MongoDB环境变量配置
4.验证安装是否成功
C:Users***.DESKTOP-C1RC9P2>mongo
MongoDB shell version v4.4.2-rc0
connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("df31999e-cb62-4f71-8a18-7db8723c514f") }
MongoDB server version: 4.4.2-rc0
---
The server generated these startup warnings when booting:
2020-10-30T16:25:16.503+08:00: Access control is not enabled for the database. Read and write access to data and configuration is unrestricted
---
---
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()
三、MongoDB使用基本介绍
MongoDB属于非关系型数据库，其数据库、表、字段等和关系型数据库 （如：MySQL数据库）有一定的差别；
MongoDB中的集合就相当于关系型数据库中的表 MongoDB中的json字符串的键相当于关系型数据库中的列名；
在操作MongoDB数据的时候全部使用json数据格式。
1.查看数据库名
命令：
show dbs
> show dbs
admin 0.000GB
config 0.000GB
local 0.000GB
2. 查看集合
命令：
ues 数据库名 show collections
> use admin
switched to db admin
> show collections
system.version
3.查询集合中的数据
命令：
db.集合名.find()
> db.system.version.find()
{ "_id" : "featureCompatibilityVersion", "version" : "4.4" }
四、创建数据库及添加数据
MongoDB不能够直接创建数据库，需要添加一条数据才能创建
1.创建数据库和插入数据
> use company
switched to db company
> db.emp.insert({"empno":100,"ename":"admin","sex":"男","age":20,"salary":800.00,"deptno":10})
WriteResult({ "nInserted" : 1 })
WriteResult({ "nInserted" : 1 })
> db.emp.insert({"empno":101,"ename":"张三","sex":"女","age":30,"salary":2500.00,"deptno":20})})})})
WriteResult({ "nInserted" : 1 })五、查询数据
查询所有数据，在查询数据前要先指定使用哪个数据库，再查询数据库中的所有集合，根据相应集 合再查询数据。
1.查询所有数据
命令：
db.集合名.find()
指定对哪个数据库操作
> use company
switched to db company
查询指定数据库后里面的所有集合
> show collections
emp
查询所有数据，一共12条数据：
> db.emp.find()
{ "_id" : ObjectId("5f9c1c5b5df291fa8194b91b"), "empno" : 100, "ename" : "admin", "sex" : "男", "age" : 20, "salary" : 800, "deptno" : 10 }
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "empno" : 101, "ename" : "张三", "sex" : "女", "age" : 30, "salary" : 2500, "deptno" : 20 }
{ "_id" : ObjectId("5f9c20945df291fa8194b91d"), "empno" : 102, "ename" : "张良", "sex" : "男", "age" : 25, "salary" : 3000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "empno" : 103, "ename" : "李明", "sex" : "女", "age" : 30, "salary" : 1800, "deptno" : 30 }
{ "_id" : ObjectId("5f9c215f5df291fa8194b91f"), "empno" : 104, "ename" : "李菲菲", "sex" : "女", "age" : 28, "salary" : 4200, "deptno" : 20 }
{ "_id" : ObjectId("5f9c219b5df291fa8194b921"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 34, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21a75df291fa8194b922"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 34, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21d85df291fa8194b923"), "empno" : 107, "ename" : "王三", "sex" : "女", "age" : 27, "salary" : 5000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "empno" : 108, "ename" : "李元芳", "sex" : "男", "age" : 33, "salary" : 10000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c227d5df291fa8194b926"), "empno" : 110, "ename" : "刘静", "sex" : "女", "age" : 25, "salary" : 3500, "deptno" : 10 }
{ "_id" : ObjectId("5f9c371b5df291fa8194b927"), "empno" : 105, "ename" : "张四", "sex" : "男", "age" : 32, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c376a29491ade8d9d3e79"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 32, "salary" : 1600, "deptno" : 30 }
2.去掉集合中重复的数据
命令：
> db.集合名.distinct("ename")
> db.emp.distinct("ename")
[
"admin",
"刘静",
"张三",
"张四",
"张良",
"李元芳",
"李元静",
"李四",
"李明",
"李菲菲",
"王三"
]
3. 查询年龄等于25的数据
> db.emp.find({"age":25})
{ "_id" : ObjectId("5f9c20945df291fa8194b91d"), "empno" : 102, "ename" : "张良", "sex" : "男", "age" : 25, "salary" : 3000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c227d5df291fa8194b926"), "empno" : 110, "ename" : "刘静", "sex" : "女", "age" : 25, "salary" : 3500, "deptno" : 10 }
4. 查询ename=“李元芳“的数据
> db.emp.find({"ename":"李元芳"})
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "empno" : 108, "ename" : "李元芳", "sex" : "男", "age" : 35, "salary" : 8000, "deptno" : 30 }
5. 查询age>30岁的员工数据
> db.emp.find({"age":{$gt:30}})
{ "_id" : ObjectId("5f9c21855df291fa8194b920"), "empno" : 105, "ename" : "张四", "sex" : "男", "age" : 32, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c219b5df291fa8194b921"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21a75df291fa8194b922"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "empno" : 108, "ename" : "李元芳", "sex" : "男", "age" : 35, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 35, "salary" : 15000, "deptno" : 36 }
6. 查询age<25的员工数据
> db.emp.find({"age":{$lt:25}})
{ "_id" : ObjectId("5f9c1c5b5df291fa8194b91b"), "empno" : 100, "ename" : "admin", "sex" : "男", "age" : 20, "salary" : 800, "deptno" : 10 }
7.查询age>=30的员工数据
> db.emp.find({"age":{$gte:30}})
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "empno" : 101, "ename" : "张三", "sex" : "女", "age" : 30, "salary" : 2500, "deptno" : 20 }
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "empno" : 103, "ename" : "李明", "sex" : "女", "age" : 30, "salary" : 1800, "deptno" : 30 }
{ "_id" : ObjectId("5f9c21855df291fa8194b920"), "empno" : 105, "ename" : "张四", "sex" : "男", "age" : 32, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c219b5df291fa8194b921"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21a75df291fa8194b922"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "empno" : 108, "ename" : "李元芳", "sex" : "男", "age" : 35, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 35, "salary" : 15000, "deptno" : 36 }
8. 查询age<=30的员工数据
> db.emp.find({"age":{$lte:30}})
{ "_id" : ObjectId("5f9c1c5b5df291fa8194b91b"), "empno" : 100, "ename" : "admin", "sex" : "男", "age" : 20, "salary" : 800, "deptno" : 10 }
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "empno" : 101, "ename" : "张三", "sex" : "女", "age" : 30, "salary" : 2500, "deptno" : 20 }
{ "_id" : ObjectId("5f9c20945df291fa8194b91d"), "empno" : 102, "ename" : "张良", "sex" : "男", "age" : 25, "salary" : 3000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "empno" : 103, "ename" : "李明", "sex" : "女", "age" : 30, "salary" : 1800, "deptno" : 30 }
{ "_id" : ObjectId("5f9c215f5df291fa8194b91f"), "empno" : 104, "ename" : "李菲菲", "sex" : "女", "age" : 28, "salary" : 4200, "deptno" : 20 }
{ "_id" : ObjectId("5f9c21d85df291fa8194b923"), "empno" : 107, "ename" : "王三", "sex" : "女", "age" : 27, "salary" : 5000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c227d5df291fa8194b926"), "empno" : 110, "ename" : "刘静", "sex" : "女", "age" : 25, "salary" : 3500, "deptno" : 10 }
9. 查询age>=25并且age<=30的员工数据
> db.emp.find({"age":{$gte:25,$lte:30}})
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "empno" : 101, "ename" : "张三", "sex" : "女", "age" : 30, "salary" : 2500, "deptno" : 20 }
{ "_id" : ObjectId("5f9c20945df291fa8194b91d"), "empno" : 102, "ename" : "张良", "sex" : "男", "age" : 25, "salary" : 3000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "empno" : 103, "ename" : "李明", "sex" : "女", "age" : 30, "salary" : 1800, "deptno" : 30 }
{ "_id" : ObjectId("5f9c215f5df291fa8194b91f"), "empno" : 104, "ename" : "李菲菲", "sex" : "女", "age" : 28, "salary" : 4200, "deptno" : 20 }
{ "_id" : ObjectId("5f9c21d85df291fa8194b923"), "empno" : 107, "ename" : "王三", "sex" : "女", "age" : 27, "salary" : 5000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c227d5df291fa8194b926"), "empno" : 110, "ename" : "刘静", "sex" : "女", "age" : 25, "salary" : 3500, "deptno" : 10 }
10. 查询全部姓李的员工数据（模糊查询）
> db.emp.find({"ename":/李/})
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "empno" : 103, "ename" : "李明", "sex" : "女", "age" : 30, "salary" : 1800, "deptno" : 30 }
{ "_id" : ObjectId("5f9c215f5df291fa8194b91f"), "empno" : 104, "ename" : "李菲菲", "sex" : "女", "age" : 28, "salary" : 4200, "deptno" : 20 }
{ "_id" : ObjectId("5f9c219b5df291fa8194b921"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21a75df291fa8194b922"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "empno" : 108, "ename" : "李元芳", "sex" : "男", "age" : 35, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 35, "salary" : 15000, "deptno" : 36 }
11. 查询姓名以“张”开头的员工数据
> db.emp.find({"ename":/^张/})
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "empno" : 101, "ename" : "张三", "sex" : "女", "age" : 30, "salary" : 2500, "deptno" : 20 }
{ "_id" : ObjectId("5f9c20945df291fa8194b91d"), "empno" : 102, "ename" : "张良", "sex" : "男", "age" : 25, "salary" : 3000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c21855df291fa8194b920"), "empno" : 105, "ename" : "张四", "sex" : "男", "age" : 32, "salary" : 8000, "deptno" : 30 }
12. 查询以姓名以“静”结尾的员工数据
> db.emp.find({"ename":/静$/})
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 35, "salary" : 15000, "deptno" : 36 }
{ "_id" : ObjectId("5f9c227d5df291fa8194b926"), "empno" : 110, "ename" : "刘静", "sex" : "女", "age" : 25, "salary" : 3500, "deptno" : 10 }
13. 查询指定列的员工数据
> db.emp.find({},{"age":1})
{ "_id" : ObjectId("5f9c1c5b5df291fa8194b91b"), "age" : 20 }
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "age" : 30 }
{ "_id" : ObjectId("5f9c20945df291fa8194b91d"), "age" : 25 }
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "age" : 30 }
{ "_id" : ObjectId("5f9c215f5df291fa8194b91f"), "age" : 28 }
{ "_id" : ObjectId("5f9c21855df291fa8194b920"), "age" : 32 }
{ "_id" : ObjectId("5f9c219b5df291fa8194b921"), "age" : 35 }
{ "_id" : ObjectId("5f9c21a75df291fa8194b922"), "age" : 35 }
{ "_id" : ObjectId("5f9c21d85df291fa8194b923"), "age" : 27 }
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "age" : 35 }
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "age" : 35 }
{ "_id" : ObjectId("5f9c227d5df291fa8194b926"), "age" : 25 }
> db.emp.find({},{"ename":1,"age":1})
{ "_id" : ObjectId("5f9c1c5b5df291fa8194b91b"), "ename" : "admin", "age" : 20 }
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "ename" : "张三", "age" : 30 }
{ "_id" : ObjectId("5f9c20945df291fa8194b91d"), "ename" : "张良", "age" : 25 }
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "ename" : "李明", "age" : 30 }
{ "_id" : ObjectId("5f9c215f5df291fa8194b91f"), "ename" : "李菲菲", "age" : 28 }
{ "_id" : ObjectId("5f9c21855df291fa8194b920"), "ename" : "张四", "age" : 32 }
{ "_id" : ObjectId("5f9c219b5df291fa8194b921"), "ename" : "李四", "age" : 35 }
{ "_id" : ObjectId("5f9c21a75df291fa8194b922"), "ename" : "李四", "age" : 35 }
{ "_id" : ObjectId("5f9c21d85df291fa8194b923"), "ename" : "王三", "age" : 27 }
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "ename" : "李元芳", "age" : 35 }
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "ename" : "李元静", "age" : 35 }
{ "_id" : ObjectId("5f9c227d5df291fa8194b926"), "ename" : "刘静", "age" : 25 }
> db.emp.find({"age":{$gte:30}},{"ename":1,"age":1,"salary":1})
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "ename" : "张三", "age" : 30, "salary" : 2500 }
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "ename" : "李明", "age" : 30, "salary" : 1800 }
{ "_id" : ObjectId("5f9c21855df291fa8194b920"), "ename" : "张四", "age" : 32, "salary" : 8000 }
{ "_id" : ObjectId("5f9c219b5df291fa8194b921"), "ename" : "李四", "age" : 35, "salary" : 12000 }
{ "_id" : ObjectId("5f9c21a75df291fa8194b922"), "ename" : "李四", "age" : 35, "salary" : 12000 }
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "ename" : "李元芳", "age" : 35, "salary" : 8000 }
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "ename" : "李元静", "age" : 35, "salary" : 15000 }
14. 排序
> db.emp.find().sort({"age":1})
{ "_id" : ObjectId("5f9c1c5b5df291fa8194b91b"), "empno" : 100, "ename" : "admin", "sex" : "男", "age" : 20, "salary" : 800, "deptno" : 10 }
{ "_id" : ObjectId("5f9c20945df291fa8194b91d"), "empno" : 102, "ename" : "张良", "sex" : "男", "age" : 25, "salary" : 3000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c227d5df291fa8194b926"), "empno" : 110, "ename" : "刘静", "sex" : "女", "age" : 25, "salary" : 3500, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21d85df291fa8194b923"), "empno" : 107, "ename" : "王三", "sex" : "女", "age" : 27, "salary" : 5000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c215f5df291fa8194b91f"), "empno" : 104, "ename" : "李菲菲", "sex" : "女", "age" : 28, "salary" : 4200, "deptno" : 20 }
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "empno" : 101, "ename" : "张三", "sex" : "女", "age" : 30, "salary" : 2500, "deptno" : 20 }
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "empno" : 103, "ename" : "李明", "sex" : "女", "age" : 30, "salary" : 1800, "deptno" : 30 }
{ "_id" : ObjectId("5f9c21855df291fa8194b920"), "empno" : 105, "ename" : "张四", "sex" : "男", "age" : 32, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c219b5df291fa8194b921"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21a75df291fa8194b922"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "empno" : 108, "ename" : "李元芳", "sex" : "男", "age" : 35, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 35, "salary" : 15000, "deptno" : 36 }
> db.emp.find().sort({salary:-1})
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 35, "salary" : 15000, "deptno" : 36 }
{ "_id" : ObjectId("5f9c219b5df291fa8194b921"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21a75df291fa8194b922"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21855df291fa8194b920"), "empno" : 105, "ename" : "张四", "sex" : "男", "age" : 32, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "empno" : 108, "ename" : "李元芳", "sex" : "男", "age" : 35, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c21d85df291fa8194b923"), "empno" : 107, "ename" : "王三", "sex" : "女", "age" : 27, "salary" : 5000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c215f5df291fa8194b91f"), "empno" : 104, "ename" : "李菲菲", "sex" : "女", "age" : 28, "salary" : 4200, "deptno" : 20 }
{ "_id" : ObjectId("5f9c227d5df291fa8194b926"), "empno" : 110, "ename" : "刘静", "sex" : "女", "age" : 25, "salary" : 3500, "deptno" : 10 }
{ "_id" : ObjectId("5f9c20945df291fa8194b91d"), "empno" : 102, "ename" : "张良", "sex" : "男", "age" : 25, "salary" : 3000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "empno" : 101, "ename" : "张三", "sex" : "女", "age" : 30, "salary" : 2500, "deptno" : 20 }
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "empno" : 103, "ename" : "李明", "sex" : "女", "age" : 30, "salary" : 1800, "deptno" : 30 }
{ "_id" : ObjectId("5f9c1c5b5df291fa8194b91b"), "empno" : 100, "ename" : "admin", "sex" : "男", "age" : 20, "salary" : 800, "deptno" : 10 }
15. 查询ename=admin且age=20的员工数据
> db.emp.find({ename:"admin",age:20})
{ "_id" : ObjectId("5f9c1c5b5df291fa8194b91b"), "empno" : 100, "ename" : "admin", "sex" : "男", "age" : 20, "salary" : 800, "deptno" : 10 }
16. 查询前5条数据
> db.emp.find().limit(5)
{ "_id" : ObjectId("5f9c1c5b5df291fa8194b91b"), "empno" : 100, "ename" : "admin", "sex" : "男", "age" : 20, "salary" : 800, "deptno" : 10 }
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "empno" : 101, "ename" : "张三", "sex" : "女", "age" : 30, "salary" : 2500, "deptno" : 20 }
{ "_id" : ObjectId("5f9c20945df291fa8194b91d"), "empno" : 102, "ename" : "张良", "sex" : "男", "age" : 25, "salary" : 3000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "empno" : 103, "ename" : "李明", "sex" : "女", "age" : 30, "salary" : 1800, "deptno" : 30 }
{ "_id" : ObjectId("5f9c215f5df291fa8194b91f"), "empno" : 104, "ename" : "李菲菲", "sex" : "女", "age" : 28, "salary" : 4200, "deptno" : 20 }
17. 查询10条以后的数据
> db.emp.find().skip(10)
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 35, "salary" : 15000, "deptno" : 36 }
{ "_id" : ObjectId("5f9c227d5df291fa8194b926"), "empno" : 110, "ename" : "刘静", "sex" : "女", "age" : 25, "salary" : 3500, "deptno" : 10 }
18. 查询集合中的总数据
> db.emp.find().count()
12
> db.emp.find({salary:{$gte:5000}}).count()
6
验证（查询查询salary>=5000的员工数据，一共是6条。）
> db.emp.find({salary:{$gte:5000}})
{ "_id" : ObjectId("5f9c21855df291fa8194b920"), "empno" : 105, "ename" : "张四", "sex" : "男", "age" : 32, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c219b5df291fa8194b921"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21a75df291fa8194b922"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21d85df291fa8194b923"), "empno" : 107, "ename" : "王三", "sex" : "女", "age" : 27, "salary" : 5000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "empno" : 108, "ename" : "李元芳", "sex" : "男", "age" : 35, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 35, "salary" : 15000, "deptno" : 36 }
19. 分页查询
第一页：
> db.emp.find().skip(0).limit(5)
{ "_id" : ObjectId("5f9c1c5b5df291fa8194b91b"), "empno" : 100, "ename" : "admin", "sex" : "男", "age" : 20, "salary" : 800, "deptno" : 10 }
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "empno" : 101, "ename" : "张三", "sex" : "女", "age" : 30, "salary" : 2500, "deptno" : 20 }
{ "_id" : ObjectId("5f9c20945df291fa8194b91d"), "empno" : 102, "ename" : "张良", "sex" : "男", "age" : 25, "salary" : 3000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "empno" : 103, "ename" : "李明", "sex" : "女", "age" : 30, "salary" : 1800, "deptno" : 30 }
{ "_id" : ObjectId("5f9c215f5df291fa8194b91f"), "empno" : 104, "ename" : "李菲菲", "sex" : "女", "age" : 28, "salary" : 4200, "deptno" : 20 }
第二页：
> db.emp.find().skip(5).limit(5)
{ "_id" : ObjectId("5f9c21855df291fa8194b920"), "empno" : 105, "ename" : "张四", "sex" : "男", "age" : 32, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c219b5df291fa8194b921"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21a75df291fa8194b922"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21d85df291fa8194b923"), "empno" : 107, "ename" : "王三", "sex" : "女", "age" : 27, "salary" : 5000, "deptno" : 20 }
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "empno" : 108, "ename" : "李元芳", "sex" : "男", "age" : 35, "salary" : 8000, "deptno" : 30 }
第三页：
> db.emp.find().skip(10).limit(5)
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 35, "salary" : 15000, "deptno" : 36 }
{ "_id" : ObjectId("5f9c227d5df291fa8194b926"), "empno" : 110, "ename" : "刘静", "sex" : "女", "age" : 25, "salary" : 3500, "deptno" : 10 }
skip的值=（页数-1）* 每页显示数量
skip（N）：表示要查询第N条数据后的数据
20.关键字or的查询方式
> db.emp.find({$or:[{age:30},{age:35}]})
{ "_id" : ObjectId("5f9c1dfc5df291fa8194b91c"), "empno" : 101, "ename" : "张三", "sex" : "女", "age" : 30, "salary" : 2500, "deptno" : 20 }
{ "_id" : ObjectId("5f9c21055df291fa8194b91e"), "empno" : 103, "ename" : "李明", "sex" : "女", "age" : 30, "salary" : 1800, "deptno" : 30 }
{ "_id" : ObjectId("5f9c219b5df291fa8194b921"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c21a75df291fa8194b922"), "empno" : 106, "ename" : "李四", "sex" : "男", "age" : 35, "salary" : 12000, "deptno" : 10 }
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "empno" : 108, "ename" : "李元芳", "sex" : "男", "age" : 35, "salary" : 8000, "deptno" : 30 }
{ "_id" : ObjectId("5f9c22445df291fa8194b925"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 35, "salary" : 15000, "deptno" : 36 }
21. 查询第一条数据
> db.emp.findOne()
{
"_id" : ObjectId("5f9c1c5b5df291fa8194b91b"),
"empno" : 100,
"ename" : "admin",
"sex" : "男",
"age" : 20,
"salary" : 800,
"deptno" : 10
}
或
> db.emp.find().limit(1)
{ "_id" : ObjectId("5f9c1c5b5df291fa8194b91b"), "empno" : 100, "ename" : "admin", "sex" : "男", "age" : 20, "salary" : 800, "deptno" : 10 }
22. 查询当前表所在的数据库
> db.emp.getDB()
company
六、更新数据
1. 更新员工李元静的年龄为32岁
> db.emp.update({ename:"李元静"},{$set:{age:32}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
验证(查询姓名是李元静的员工数据)
> db.emp.find({ename:"李元静"})
{ "_id" : ObjectId("5f9c376a29491ade8d9d3e79"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 32, "salary" : 15000, "deptno" : 36 }
2. 更新员工李元静的薪资为1600并且所在部门修改为30
> db.emp.update({ename:"李元静"},{$set:{salary:1600,deptno:30}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.emp.find({ename:"李元静"})
{ "_id" : ObjectId("5f9c376a29491ade8d9d3e79"), "empno" : 109, "ename" : "李元静", "sex" : "女", "age" : 32, "salary" : 1600, "deptno" : 30 }
3. 批量更新数据
把年龄是35岁的更新为34岁
设置第三个参数：{multi:true}
> db.emp.update({age:35},{$set:{age:34}},{multi:true})
WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })
4. $inc使用
$inc将一个字段的值增加或者减少
把李元芳的年龄减少1岁，同时薪资加2000
> db.emp.update({ename:"李元芳"},{$inc:{age:-1,salary:2000}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.emp.find({ename:"李元芳"})
{ "_id" : ObjectId("5f9c22185df291fa8194b924"), "empno" : 108, "ename" : "李元芳", "sex" : "男", "age" : 33, "salary" : 10000, "deptno" : 30 }
七、删除操作
1. 删除指定条件的数据
db.emp.remove({ename:"李元芳"})
2. 删除所有数据
db.emp.remove({})
3. 删除集合
db.emp.drop()
4.删除数据库
db.dropDatabase()
5. 温馨提示
八、MongoDB数据库索引
1. 模拟批量插入数据
> use com
switched to db com
> for(var i=0;i<600000;i++){
... db.users.insert({userNo:i,userName:"张三"+i,age:28,phone:"13000"+i})
... }
WriteResult({ "nInserted" : 1 })
> db.users.find().count()
600000
2.无索引查询所耗费时间
命令：
db.users.find({userNo:599999}).explain("executionStats")
> db.users.find({userNo:599999}).explain("executionStats")
{
"queryPlanner" : {
"plannerVersion" : 1,
"namespace" : "com.users",
"indexFilterSet" : false,
"parsedQuery" : {
"userNo" : {
"$eq" : 599999
}
},
"winningPlan" : {
"stage" : "COLLSCAN",
"filter" : {
"userNo" : {
"$eq" : 599999
}
},
"direction" : "forward"
},
"rejectedPlans" : [ ]
},
"executionStats" : {
"executionSuccess" : true,
"nReturned" : 1,
"executionTimeMillis" : 254,
"totalKeysExamined" : 0,
"totalDocsExamined" : 600000,
"executionStages" : {
"stage" : "COLLSCAN",
"filter" : {
"userNo" : {
"$eq" : 599999
}
},
"nReturned" : 1,
"executionTimeMillisEstimate" : 3,
"works" : 600002,
"advanced" : 1,
"needTime" : 600000,
"needYield" : 0,
"saveState" : 600,
"restoreState" : 600,
"isEOF" : 1,
"direction" : "forward",
"docsExamined" : 600000
}
},
"serverInfo" : {
"host" : "thinkPadE580",
"port" : 27017,
"version" : "4.4.2-rc0",
"gitVersion" : "b5fafa1f87dda6f8773c5a8a1a5e7776d4d94da7"
},
"ok" : 1
}
3. 创建索引
命令：
db.users.ensureIndex({userNo:1})
> db.users.ensureIndex({userNo:1})
{
"createdCollectionAutomatically" : false,
"numIndexesBefore" : 1,
"numIndexesAfter" : 2,
"ok" : 1
}
4. 查询索引
命令：
db.users.getIndexes()
> db.users.getIndexes()
[
{
"v" : 2,
"key" : {
"_id" : 1
},
"name" : "_id_"
},
{
"v" : 2,
"key" : {
"userNo" : 1
},
"name" : "userNo_1"
}
]
5. 使用索引查询所耗费时间
> db.users.find({userNo:599999}).explain("executionStats")
{
"queryPlanner" : {
"plannerVersion" : 1,
"namespace" : "com.users",
"indexFilterSet" : false,
"parsedQuery" : {
"userNo" : {
"$eq" : 599999
}
},
"winningPlan" : {
"stage" : "FETCH",
"inputStage" : {
"stage" : "IXSCAN",
"keyPattern" : {
"userNo" : 1
},
"indexName" : "userNo_1",
"isMultiKey" : false,
"multiKeyPaths" : {
"userNo" : [ ]
},
"isUnique" : false,
"isSparse" : false,
"isPartial" : false,
"indexVersion" : 2,
"direction" : "forward",
"indexBounds" : {
"userNo" : [
"[599999.0, 599999.0]"
]
}
}
},
"rejectedPlans" : [ ]
},
"executionStats" : {
"executionSuccess" : true,
"nReturned" : 1,
"executionTimeMillis" : 84,
"totalKeysExamined" : 1,
"totalDocsExamined" : 1,
"executionStages" : {
"stage" : "FETCH",
"nReturned" : 1,
"executionTimeMillisEstimate" : 0,
"works" : 2,
"advanced" : 1,
"needTime" : 0,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"docsExamined" : 1,
"alreadyHasObj" : 0,
"inputStage" : {
"stage" : "IXSCAN",
"nReturned" : 1,
"executionTimeMillisEstimate" : 0,
"works" : 2,
"advanced" : 1,
"needTime" : 0,
"needYield" : 0,
"saveState" : 0,
"restoreState" : 0,
"isEOF" : 1,
"keyPattern" : {
"userNo" : 1
},
"indexName" : "userNo_1",
"isMultiKey" : false,
"multiKeyPaths" : {
"userNo" : [ ]
},
"isUnique" : false,
"isSparse" : false,
"isPartial" : false,
"indexVersion" : 2,
"direction" : "forward",
"indexBounds" : {
"userNo" : [
"[599999.0, 599999.0]"
]
},
"keysExamined" : 1,
"seeks" : 1,
"dupsTested" : 0,
"dupsDropped" : 0
}
}
},
"serverInfo" : {
"host" : "thinkPadE580",
"port" : 27017,
"version" : "4.4.2-rc0",
"gitVersion" : "b5fafa1f87dda6f8773c5a8a1a5e7776d4d94da7"
},
"ok" : 1
}
6. 删除索引
命令：
db.users.dropIndex({userNo:1})
验证
> db.users.dropIndex({userNo:1})
{ "nIndexesWas" : 2, "ok" : 1 }
7. 复合索引
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