通过Javascript shell操作MongoDB

macOs 安装MongoDB

1.更新 Homebrew的package数据库（macosx上的软件包管理工具）

$ brew update

2.安装MongoDb

$ brew install mongodb

3.启动MongoDb

$ brew services start mongodb

4.连接到mongo

$ mongo

5.关闭MongoDb

$ brew services stop mongodb

如果安装过程遇到如下错误

Error: An unexpected error occurred during the `brew link` step
The formula built, but is not symlinked into /usr/local
Permission denied @ dir_s_mkdir - /usr/local/Frameworks
Error: Permission denied @ dir_s_mkdir - /usr/local/Frameworks

执行以下命令

sudo chown -R $(whoami) $(brew --prefix)/*
sudo install -d -o $(whoami) -g admin /usr/local/Frameworks

数据库，集合和文档

mongoDB把数据储存在文档中，数据可以以Json的格式输出。我们可以在不同的地方储存不同的文档，如文档usrs 和orders，一些文档以某种方式分类，成为集合，我们把集合储存在不同的数据库中。

切换数据库

> use tutorial
switched to db tutorial

创建第一个文档，因为使用javascript shell，文档使用JSON

> {username: "smith"}
smith

插入和查询

插入文档需要指定插入的集合,我们选择users集合

> db.users.insert({username: "smith"})
WriteResult({ "nInserted" : 1 })

如果插入成功，就成功保存了第一个文档

> db.users.find()
{ "_id" : ObjectId("5c00fba91fa39c550ae90b8d"), "username" : "smith" }

_id是文档的主键

继续插入

> db.users.insert({username: "john"})
WriteResult({ "nInserted" : 1 })
> db.users.count()
2
> db.users.find()
{ "_id" : ObjectId("5c00fba91fa39c550ae90b8d"), "username" : "smith" }
{ "_id" : ObjectId("5c00fc831fa39c550ae90b8e"), "username" : "john" }
> db.users.find({username: "john"})
{ "_id" : ObjectId("5c00fc831fa39c550ae90b8e"), "username" : "john" }

可以多个条件查询

> db.users.find({ "_id" : ObjectId("5c00fc831fa39c550ae90b8e"), "username" : "john" })
{ "_id" : ObjectId("5c00fc831fa39c550ae90b8e"), "username" : "john" }

等价于使用$and

> db.users.find({$and: [{"_id" : ObjectId("5c00fc831fa39c550ae90b8e")}, {"username" : "john"}]})

{ "_id" : ObjectId("5c00fc831fa39c550ae90b8e"), "username" : "john" }

也可以使用$or来进行或查询

> db.users.find({$or: [{"username" : "smith"}, {"username" : "john"}]})
{ "_id" : ObjectId("5c00fba91fa39c550ae90b8d"), "username" : "smith" }
{ "_id" : ObjectId("5c00fc831fa39c550ae90b8e"), "username" : "john" }

更新

指定文档，指定更新内容。注意使用$set,表示是更新当前文档

> db.users.update({username:"smith"},{$set: {country: "usa"}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

想要删除country，使用$unset

> db.users.update({username:"smith"},{$unset: {country: 1}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })

> db.users.update({username:"smith"},{$set: {favorites:{movies: ["movie1", "movie2"]}}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.users.find({username:"smith"}).pretty()
{
    "_id" : ObjectId("5c00fba91fa39c550ae90b8d"),
    "username" : "smith",
    "country" : "usa",
    "favorites" : {
        "movies" : [
            "movie1",
            "movie2"
        ]
    }
}

删除

> db.users.remove({username:"smith"})
WriteResult({ "nRemoved" : 1 })

删除整个文档用drop