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前言

各位FEer，大家好。最近呢，公司项目没有之前那么紧啦，我就在自己驱动学习下其他周边知识，因为想做一个全栈型的开发者，所以我就着手学习了Nodejs做后端接口和MongoDB做数据库存储这样一个架构。写了一个原生的移动App。今天我们来分享下MongoDB数据库的学习新得。

数据库初识

众所周知，数据库的存在对于技术开发者来说，就好比是仓库，用来存储信息的仓库。而一般数据库又分为关系型数据库和非关系型数据库。关系型数据库比较常见的是Mysql和Oracle，非关系数据库比较常见的是memcached（key-value），redis（key-value），和mongoDB（Document-oriented）等等很多NoSQL数据库。

MongoDB的特点

MongoDB是一个介于关系型数据库和非关系型数据库之间的产品，是非关系型数据库当中功能最丰富，最像关系数据库的。他支持的数据库结构非常松散，类似json的bjson格式，因此可以存储比较复杂的数据类型。Mongodb最大的特点是他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。

特点

• 高性能
• 易部署
• 易使用
• 存储数据非常方便

主要功能特性

• 面向集合存储，易存储对象类型的数据
  “面向集合”（Collenction-Orented）意思是数据库被分组存储在数据集中，被称为一个集合（Collenction）每个 集合在数据库中都有一个唯一的标识名，并且可以包含无限数目的文档，集合的概念类似关系型数据库（RDBMS）里的表（table）不同的是它不需要定义任何模式（schema）
• 模式自由
  模式自由（schema-free）意为着存储在mongodb数据库中的文件，我们不需要知道它的任何结构定义。
• 支持动态查询
• 支持完全索引，包含内部对象
• 支持查询
• 支持复制和故障恢复
• 使用高效的二进制数据存储，包括大型对象
• 自动处理碎片、以支持云计算层次的扩展性

学习细节

1. 启动mongoDB数据库

xuhao@localhost private-code$ cd MongoDB-Project/xuhao@localhost MongoDB-Project$ mongod

2. 进入命令行操作

xuhao@localhost MongoDB-Project$ mongoMongoDB shell version v4.0.13connecting to: mongodb://127.0.0.1:27017/?gssapiServiceName=mongodbImplicit session: session { "id" : UUID("ccf999e2-2300-4438-acef-4a8bb23862f5") }MongoDB server version: 4.0.13

// mongo命令行模式下，练习基本操作命令> var a = 5> print a2019-12-09T22:24:39.248+0800 E QUERY    [js] SyntaxError: missing ; before statement @(shell):1:6> print(a)5> function sum(x,y){... return x+y;... }> sum(5,6)11> show dbsadmin   0.000GBconfig  0.000GBlocal   0.000GB> use weichuangswitched to db weichuang> show dbsadmin   0.000GBconfig  0.000GBlocal   0.000GB> dbweichuang> show collections> db.user.insert({"name":"xuhao"})WriteResult({ "nInserted" : 1 })> db.user.find(){ "_id" : ObjectId("5dee5a2df4dd815948930114"), "name" : "xuhao" }> db.user.insert({"name":"luolanyu"})WriteResult({ "nInserted" : 1 })> db.user.find(){ "_id" : ObjectId("5dee5a2df4dd815948930114"), "name" : "xuhao" }{ "_id" : ObjectId("5dee5a75f4dd815948930115"), "name" : "luolanyu" }> db.user.findOne(){ "_id" : ObjectId("5dee5a2df4dd815948930114"), "name" : "xuhao" }> db.user.remove({"name":"xuhao"})WriteResult({ "nRemoved" : 1 })> db.user.find(){ "_id" : ObjectId("5dee5a75f4dd815948930115"), "name" : "luolanyu" }> db.user.drop()true> db.user.find()> load('./1.js')connecting to: mongodb://127.0.0.1:27017/weichuangImplicit session: session { "id" : UUID("a2e0831a-e3ee-449d-98bc-62ab536381e3") }MongoDB server version: 4.0.13Insert Success!true// 清空数据库> db.user.drop()true// 查询数据库（此时为空）> db.user.find()> // 插入多个数据> load('2.js')connecting to: mongodb://127.0.0.1:27017/weichuangImplicit session: session { "id" : UUID("f3d004c8-20d0-4d0e-a5e9-0ec57b273d8a") }MongoDB server version: 4.0.13Insert Success!true> db.user.find(){ "_id" : ObjectId("5dee627166e1e1543cfcf6b9"), "name" : "xutiantian", "age" : 11, "hobby" : [ "画画", "弹琴", "民族舞" ], "piano" : { "brand" : "Bluthner", "price" : 140000 } }{ "_id" : ObjectId("5dee627166e1e1543cfcf6ba"), "name" : "wangqianqian", "age" : 12, "hobby" : [ "毛笔字", "弹琴", "民族舞" ], "piano" : { "brand" : "Fazioli", "price" : 110000 } }{ "_id" : ObjectId("5dee627166e1e1543cfcf6bb"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "吃饭", "弹琴", "民族舞" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }// 更新数据库中的数据（错误方式，会覆盖并丢数据）> db.user.update({name:'xutiantian'},{age:10})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.user.find(){ "_id" : ObjectId("5dee627166e1e1543cfcf6b9"), "age" : 10 }{ "_id" : ObjectId("5dee627166e1e1543cfcf6ba"), "name" : "wangqianqian", "age" : 12, "hobby" : [ "毛笔字", "弹琴", "民族舞" ], "piano" : { "brand" : "Fazioli", "price" : 110000 } }{ "_id" : ObjectId("5dee627166e1e1543cfcf6bb"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "吃饭", "弹琴", "民族舞" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }// 某一条数据更新（正确方式，但不方便）> db.user.update({ name: 'xutiantian' }, {...   name: 'xutiantian',...   age: 10,...   hobby: ['画画', '弹琴', '民族舞'],...   piano: {...     brand: 'Bluthner',...     price: 140000...   }... })WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.user.find(){ "_id" : ObjectId("5dee649f66e1e1543cfcf6bf"), "name" : "xutiantian", "age" : 10, "hobby" : [ "画画", "弹琴", "民族舞" ], "piano" : { "brand" : "Bluthner", "price" : 140000 } }{ "_id" : ObjectId("5dee649f66e1e1543cfcf6c0"), "name" : "wangqianqian", "age" : 12, "hobby" : [ "毛笔字", "弹琴", "民族舞" ], "piano" : { "brand" : "Fazioli", "price" : 110000 } }{ "_id" : ObjectId("5dee649f66e1e1543cfcf6c1"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "吃饭", "弹琴", "民族舞" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }// // 某一条数据更新（正确方式，方便）> db.user.update({name:'xutiantian'},{$set:{age: 11.5}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.user.find(){ "_id" : ObjectId("5dee649f66e1e1543cfcf6bf"), "name" : "xutiantian", "age" : 11.5, "hobby" : [ "画画", "弹琴", "民族舞" ], "piano" : { "brand" : "Bluthner", "price" : 140000 } }{ "_id" : ObjectId("5dee649f66e1e1543cfcf6c0"), "name" : "wangqianqian", "age" : 12, "hobby" : [ "毛笔字", "弹琴", "民族舞" ], "piano" : { "brand" : "Fazioli", "price" : 110000 } }{ "_id" : ObjectId("5dee649f66e1e1543cfcf6c1"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "吃饭", "弹琴", "民族舞" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }> db.user.drop()true> db.user.find()> load('2.js')connecting to: mongodb://127.0.0.1:27017/weichuangImplicit session: session { "id" : UUID("a391815d-fd2a-4012-819f-b488ecbfb648") }MongoDB server version: 4.0.13Insert Success!true> db.user.find(){ "_id" : ObjectId("5defb269af75827244d1f227"), "name" : "xutiantian", "age" : 11, "hobby" : [ "画画", "弹琴", "民族舞" ], "piano" : { "brand" : "Bluthner", "price" : 140000 } }{ "_id" : ObjectId("5defb269af75827244d1f228"), "name" : "wangqianqian", "age" : 12, "hobby" : [ "毛笔字", "弹琴", "民族舞" ], "piano" : { "brand" : "Fazioli", "price" : 110000 } }{ "_id" : ObjectId("5defb269af75827244d1f229"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "吃饭", "弹琴", "民族舞" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }// 删除一条数据中的某个值(unset)> db.user.update({name:'wangqianqian'},{$unset:{'hobby':''}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.user.find(){ "_id" : ObjectId("5defb269af75827244d1f227"), "name" : "xutiantian", "age" : 11, "hobby" : [ "画画", "弹琴", "民族舞" ], "piano" : { "brand" : "Bluthner", "price" : 140000 } }{ "_id" : ObjectId("5defb269af75827244d1f228"), "name" : "wangqianqian", "age" : 12, "piano" : { "brand" : "Fazioli", "price" : 110000 } }{ "_id" : ObjectId("5defb269af75827244d1f229"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "吃饭", "弹琴", "民族舞" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }// upsert: 如果有某一个属性，则去更新，如果没有这个属性，则插入这个属性> db.user.update({name:'xutiantian'},{$set: {age: 10}},{upsert: true})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.user.find(){ "_id" : ObjectId("5defb269af75827244d1f227"), "name" : "xutiantian", "age" : 10, "hobby" : [ "画画", "弹琴", "民族舞" ], "piano" : { "brand" : "Bluthner", "price" : 140000 } }{ "_id" : ObjectId("5defb269af75827244d1f228"), "name" : "wangqianqian", "age" : 12, "piano" : { "brand" : "Fazioli", "price" : 110000 } }{ "_id" : ObjectId("5defb269af75827244d1f229"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "吃饭", "弹琴", "民族舞" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }// multi  给每条数据的某个属性统一为一个值， 如果没有multi: true，则只会作用于第一条数据> db.user.update({}, {$set: {hobby:['弹琴']}}, {multi: true})WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })> db.user.find(){ "_id" : ObjectId("5defb269af75827244d1f227"), "name" : "xutiantian", "age" : 10, "hobby" : [ "弹琴" ], "piano" : { "brand" : "Bluthner", "price" : 140000 } }{ "_id" : ObjectId("5defb269af75827244d1f228"), "name" : "wangqianqian", "age" : 12, "piano" : { "brand" : "Fazioli", "price" : 110000 }, "hobby" : [ "弹琴" ] }{ "_id" : ObjectId("5defb269af75827244d1f229"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "弹琴" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }// push 在某条数据中给数组格式的数据属性中添加一个新的值> db.user.update({name: 'liangyunwei'}, {$push:{hobby: '玩游戏'}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.user.find(){ "_id" : ObjectId("5defb269af75827244d1f227"), "name" : "xutiantian", "age" : 10, "hobby" : [ "弹琴" ], "piano" : { "brand" : "Bluthner", "price" : 140000 } }{ "_id" : ObjectId("5defb269af75827244d1f228"), "name" : "wangqianqian", "age" : 12, "piano" : { "brand" : "Fazioli", "price" : 110000 }, "hobby" : [ "弹琴" ] }{ "_id" : ObjectId("5defb269af75827244d1f229"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "弹琴", "玩游戏" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }// addToSet 查找某条数据中数组格式的数据属性中是否有这个属性值（检查），如果不存在，则插入// 如果是push，并不会进行检查，则插入的数据可能会重复> db.user.update({name: 'xutiantian'}, {$addToSet: {hobby: '睡觉'}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.user.find(){ "_id" : ObjectId("5defb269af75827244d1f227"), "name" : "xutiantian", "age" : 10, "hobby" : [ "弹琴", "睡觉" ], "piano" : { "brand" : "Bluthner", "price" : 140000 } }{ "_id" : ObjectId("5defb269af75827244d1f228"), "name" : "wangqianqian", "age" : 12, "piano" : { "brand" : "Fazioli", "price" : 110000 }, "hobby" : [ "弹琴" ] }{ "_id" : ObjectId("5defb269af75827244d1f229"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "弹琴", "玩游戏" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }// each 把好几个属性每一个都插入到数据库中> var newHobby = ['吃零食','出去玩','学习'];> db.user.update({name: 'xutiantian'}, {$addToSet: {hobby:{$each: newHobby}}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.user.find(){ "_id" : ObjectId("5defb269af75827244d1f227"), "name" : "xutiantian", "age" : 10, "hobby" : [ "弹琴", "睡觉", "吃零食", "出去玩", "学习" ], "piano" : { "brand" : "Bluthner", "price" : 140000 } }{ "_id" : ObjectId("5defb269af75827244d1f228"), "name" : "wangqianqian", "age" : 12, "piano" : { "brand" : "Fazioli", "price" : 110000 }, "hobby" : [ "弹琴" ] }{ "_id" : ObjectId("5defb269af75827244d1f229"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "弹琴", "玩游戏" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }// 把某个属性中的值（按照下标）修改> db.user.update({name: 'xutiantian'}, {$set: {'hobby.0':'看动画片'}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.user.find(){ "_id" : ObjectId("5defb269af75827244d1f227"), "name" : "xutiantian", "age" : 10, "hobby" : [ "看动画片", "睡觉", "吃零食", "出去玩", "学习" ], "piano" : { "brand" : "Bluthner", "price" : 140000 } }{ "_id" : ObjectId("5defb269af75827244d1f228"), "name" : "wangqianqian", "age" : 12, "piano" : { "brand" : "Fazioli", "price" : 110000 }, "hobby" : [ "弹琴" ] }{ "_id" : ObjectId("5defb269af75827244d1f229"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "弹琴", "玩游戏" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }//findAndModify 应答式的，会返回成功或失败的结果 // 3.jsvar modify = {  findAndModify: 'user',  query: {name: 'xutiantian'},  update: {$set: {age: 11}},  new: true}; var result = db.runCommand(modify);printjson(result);> load('3.js'){        "lastErrorObject" : {                "n" : 1,                "updatedExisting" : true        },        "value" : {                "_id" : ObjectId("5defb269af75827244d1f227"),                "name" : "xutiantian",                "age" : 11,                "hobby" : [                        "看动画片",                        "睡觉",                        "吃零食",                        "出去玩",                        "学习"                ],                "piano" : {                        "brand" : "Bluthner",                        "price" : 140000                }        },        "ok" : 1}true> db.user.drop()> load('2.js')// 按条件范围查询查找 大于等于12 小于等于15> db.user.find( ...   {age: {$gte:12, $lte: 15}}... ){ "_id" : ObjectId("5df4b5da39980975e9ca7b9a"), "name" : "wangqianqian", "age" : 12, "hobby" : [ "毛笔字", "弹琴", "民族舞" ], "piano" : { "brand" : "Fazioli", "price" : 110000 } }{ "_id" : ObjectId("5df4b5da39980975e9ca7b9b"), "name" : "liangyunwei", "age" : 12, "hobby" : [ "吃饭", "弹琴", "民族舞" ], "piano" : { "brand" : "C. Bechstein", "price" : 310000 } }// 按条件范围查找，大于10，小于14> db.user.find( ...   {age: {$gt:10, $lt: 14}}, ...   {name: true, age: true}... ){ "_id" : ObjectId("5e0aacf66ad7fc9f6c8bc5b8"), "name" : "xutiantian", "age" : 11 }// 按条件查找，含某些条件> db.user.find(...   {age: {$in: [10,11]}},...   {name: true, age: true, _id: false}... ){ "name" : "xutiantian", "age" : 11 }>// “或”逻辑，按条件查找，满足其一就行> db.user.find({...   $or: [...     {age: {$gte: 18}},...     {'piano.brand': 'Fazioli'}...   ]},  ...   {name: true, age: true, _id: false}... ){ "name" : "wangqianqian", "age" : 14 }{ "name" : "liangyunwei", "age" : 18 }// “与”逻辑，全部条件同时满足进行查询// db.user.find({//   $and: [//     {age: {$gte: 18}},//     {'piano.brand': 'Fazioli'}//   ]},   //   {name: true, age: true, _id: false}// )// 无数据满足// “非逻辑”，查找不是当前条件的数据项 not// 精确匹配 必须全部满足// 如果有[],则表示数据要完全一致，才能被查到> db.user.find(...  {hobby: ['毛笔字', '弹琴', '民族舞']},...  {name: true, age: true, _id: false}...){ "name" : "wangqianqian", "age" : 14 }// 模糊查询，// 没有[]， 只要含这个条件，则筛选出所有数据> db.user.find(...  {hobby: '弹琴'},...  {name: true, age: true, _id: false}...)// 数组查询 ，$all, 需要这些条件都存在，才符合条件 > db.user.find(...   {hobby: {$all: ['画画', '弹琴']}},...   {name: true, age: true, _id: false}... ){ "name" : "xutiantian", "age" : 11 }// 数组查询 ，$in, 需要这些条件符合一个，即可> db.user.find(...   {hobby: {$in:['画画', '吃饭']}}, ...   {name: true, age: true, _id: false}... ){ "name" : "xutiantian", "age" : 11 }{ "name" : "liangyunwei", "age" : 18 }// 数组查询 ，可根据某个数据项的个数去筛选> db.user.find(...   {hobby: {$size:3}}, ...   {name: true, age: true, _id: false}... ){ "name" : "xutiantian", "age" : 11 }{ "name" : "wangqianqian", "age" : 14 }{ "name" : "liangyunwei", "age" : 18 }// 分页查询，其中limit代表每次显示几条数据，skip代表跳过几条数据，sort代表排序【-1是降序，1是升序】> db.user.find(...   {},...   {name: true, age: true, _id: false}... ).limit(1).skip(0).sort({age: -1}){ "name" : "liangyunwei", "age" : 18 }

总结

前端技术庞而杂，所以我们需要不断的精进，提高技术的深度和广度。谢谢各位同学，如果这篇文章对您有用的话，麻烦记得点赞收藏哦！😄

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