MongoDB学了总结（Mac 下实践一）

用户11690639

发布于 2026-06-18 07:59:26

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MongDB是开源的document型数据库（非关系型数据库）支持NOSQL，是用C++编写的，但他的结构是最类似于关系型数据库的，支持K-V存储。

为什么选择mongdb?

第一它存储的内容为对象和JSON格式

第二可以在任何属性上加索引；

第三可复制并支持自动故障转移，自动恢复等功能，使其具有高可用性；（待补全）

第四自动分片（待补全）

下为MongDB存储内容需要注意的几点（不局限于这几点）

键是字符串UTF-8字符串(少数例外)；键不能空字符串\0，这个字符串表示键的结尾。

（1）键值区分大小写 {“foo”:123}不同于{“Foo”:123}

（2）值区分类型{“foo”:123}不同于{“foo”: “123”}

（3）键不能为空；键不能重复

（4）键值是有序的{“x”:1, “y”:2}不同于{“y”:2, “x”:1}

1.MongoDB安装部署

（1）brew installmongodb

我本地的安装路径为供参考：/usr/local/Cellar/mongodb/3.4.9/bin

安装后的配置文件路径为：/usr/local/etc/mongod.conf，内容如下所示:

systemLog:

 destination: file

 path: /usr/local/var/log/mongodb/mongo.log

 logAppend: true

storage:

 dbPath: /usr/local/var/mongodb

net:

 bindIp: 127.0.0.1

（2）创建目录 mkdir-p /data/db 并为其赋予权限 chown `id -u` /data/db,这个应该是用来存储数据文件的，里面包括索引文件和collection文件内容

（3）需要配环境变量，不然启动时需要进入到mongodb的bin路径下执行。环境变量配置如下所示：

vi ~/.bash_profile   加入如下一行：export PATH="/usr/local/Cellar/mongodb/3.4.9/bin:$PATH"

启动命令为：mongod

（4）进入shell命令模式便可持行mongo命令了并支持jS交互。命令为：mongo

2.常用命令总结

（1）查看相关

mongod :启动mongdb
mongo: 开启Mongo的shell命令
> showdbs :查看用多少个数据库
> show collections:查看所有集合
> db:查看当前使用DB
> usemydb:切换DB，如不丰会自动创建
db.collectionName.find().pretty()注：pretty()显示可以格式化显示

（2）增加相关

    db.createCollection(“zltest”):创建collection(相当于创建表)
    db.zltest1.insert({"title":"engineer","dept":21,"group":"XXAQ"})：创建一个集合并为其存放文档，如果集合存在则写入，不存在会自动创建
    db.createCollection("mycol",{ capped : true, autoIndexId : true, size : 6142800, max : 10000 } )
    注：上述中参数说明：capped:Boolean[true自动扩容collection]；autoIndexId:Boolean[true在_id上创建索引默认为false]; size:number[配合capped=true使用指collection的最大值];max:number[指指documents的最大值]
    以下为增加document内容示例：

（3）修改document

db.mongTest.update({"name":"zhanglu"},{$set:{"name":"zhanglu888"}})

注：修改还可以用save方法同时可以保存多条，insert和update的区别在于，update存在则修改，不存在增加;insert只用于增加操作

（4）删除document

    db.mongTest.remove({"name":"zhanglu888"})

（5）复杂查询总结

按列查询：db.zltest.find({},{"id":1,"name":1,_id:0}) ，使用按列查询时需要注意_id总会显示，所以需要_id:0指定不显示

db.zltest.find({},{"id":1,"name":1,_id:0})

{ "name" : "zl" }
{ "id" : 1 }
{ "id" : 2 }
{ "id" : 3 }
{ "id" : 4 }
{ "id" : 5 }
{ "name" : "test0", "id" : 0 }
{ "name" : "test1", "id" : 1 }
{ "name" : "test2", "id" : 2 }

条件查询【where】：

已知存在数据如下：

db.zltest.find()
{ "_id" : ObjectId("59cb36db25238f9e9cb9774f"), "name" : "zl", "age" : 33, "no" : "03130321" }
{ "_id" : ObjectId("59cc9beecd12a63a4befaba8"), "title" : "mongoDB", "id" : 1, "likes" : 100, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9db"), "title" : "mongoDB1", "id" : 2, "likes" : 110, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9dc"), "title" : "mongoDB2", "id" : 3, "likes" : 210, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9dd"), "title" : "mongoDB3", "id" : 4, "likes" : 310, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9de"), "title" : "mongoDB4", "id" : 5, "likes" : 410, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdf6815f77c2c6c7f327ae"), "name" : "test0", "id" : 0 }
{ "_id" : ObjectId("59cdf6815f77c2c6c7f327af"), "name" : "test1", "id" : 1 }
{ "_id" : ObjectId("59cdf6815f77c2c6c7f327b0"), "name" : "test2", "id" : 2 }

where key=value ---- {key:value} 注：默认_id是显示的，如下查询可以不查询_id

 db.zltest.find({},{"id":1,"name":1,_id:0})
{ "name" : "zl" }
{ "id" : 1 }
{ "id" : 2 }
{ "id" : 3 }
{ "id" : 4 }
{ "id" : 5 }
{ "name" : "test0", "id" : 0 }
{ "name" : "test1", "id" : 1 }
{ "name" : "test2", "id" : 2 }

where key<value ---- {key:{$lt:value}}

示例内容略。。。。

where key<=value ---- {key:{$lte:value}}

db.zltest.find({"likes":{$lte:110}})
{ "_id" : ObjectId("59cc9beecd12a63a4befaba8"), "title" : "mongoDB", "id" : 1, "likes" : 100, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9db"), "title" : "mongoDB1", "id" : 2, "likes" : 110, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }

key>value ---- {key:{$gt:value}}

示例内容略。。。

key>=value ---- {key:{$gte:value}}

db.zltest.find({"likes":{$gte:110}})
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9db"), "title" : "mongoDB1", "id" : 2, "likes" : 110, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9dc"), "title" : "mongoDB2", "id" : 3, "likes" : 210, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9dd"), "title" : "mongoDB3", "id" : 4, "likes" : 310, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9de"), "title" : "mongoDB4", "id" : 5, "likes" : 410, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }

key!=value ---- {key:{$ne:value}}

db.zltest.find({"title":{$ne:"mongoDB"}})
{ "_id" : ObjectId("59cb36db25238f9e9cb9774f"), "name" : "zl", "age" : 33, "no" : "03130321" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9db"), "title" : "mongoDB1", "id" : 2, "likes" : 110, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9dc"), "title" : "mongoDB2", "id" : 3, "likes" : 210, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9dd"), "title" : "mongoDB3", "id" : 4, "likes" : 310, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9de"), "title" : "mongoDB4", "id" : 5, "likes" : 410, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdf6815f77c2c6c7f327ae"), "name" : "test0", "id" : 0 }
{ "_id" : ObjectId("59cdf6815f77c2c6c7f327af"), "name" : "test1", "id" : 1 }
{ "_id" : ObjectId("59cdf6815f77c2c6c7f327b0"), "name" : "test2", "id" : 2 }

key1=value1 and key2=value2 ---- {$and:[{key1:value1},{key2:value2}]}

db.zltest.find({$and:[{"url":"http://www.tutorialspoint.com/mongodb/"},{"likes":210}]})
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9dc"), "title" : "mongoDB2", "id" : 3, "likes" : 210, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }

key1=value1 and(key2=value2 or key3=value3) ---- {$or:[{key1:value1},{key2:value2}]}

db.zltest.find({"likes":210,$or:[{"likes":310},{"likes":210}]})
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9dc"), "title" : "mongoDB2", "id" : 3, "likes" : 210, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }

其它函数sort()、skip()、limit()

db.zltest.find().skip(6).limit(2).sort({"id":1})
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9dc"), "title" : "mongoDB2", "id" : 3, "likes" : 210, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }
{ "_id" : ObjectId("59cdb54ea30515a6bffcf9dd"), "title" : "mongoDB3", "id" : 4, "likes" : 310, "description" : "database", "url" : "http://www.tutorialspoint.com/mongodb/", "by" : "tutorials point" }

上述例子发现是先持行了sort然后持行skip和limit 。期中sort({"排序列字段名":1代表升序0代表降序})

分组函数aggregate ,用法格式为 db.collectionName.aggregate([{group:{"columnName":"sum:"columnName1"}}}]) 注：如果查询总记录数时，

已知数据内容如下所示:db.mongTest.find()
{ "_id" : ObjectId("59ce043a5f77c2c6c7f327b1"), "id" : 0, "name" : "zl", "salary" : 0 }
{ "_id" : ObjectId("59ce043a5f77c2c6c7f327b2"), "id" : 1, "name" : "zl", "salary" : 1000 }
{ "_id" : ObjectId("59ce043a5f77c2c6c7f327b3"), "id" : 2, "name" : "zl", "salary" : 2000 }
{ "_id" : ObjectId("59ce04575f77c2c6c7f327b4"), "id" : 3, "name" : "xxn", "salary" : 6000 }
{ "_id" : ObjectId("59ce04575f77c2c6c7f327b5"), "id" : 4, "name" : "xxn", "salary" : 8000 }
{ "_id" : ObjectId("59ce04575f77c2c6c7f327b6"), "id" : 5, "name" : "xxn", "salary" : 10000 }

b.mongTest.aggregate([{$group:{_id:"$name",totalSalary:{$sum:"$salary"},num:{$sum:1}}}])
{ "_id" : "xxn", "totalSalary" : 24000, "num" : 3 }
{ "_id" : "zl", "totalSalary" : 3000, "num" : 3 }

exists 和 in的使用方法

db.zltest.find({title:{$exists:false}})
{ "_id" : ObjectId("59cb36db25238f9e9cb9774f"), "name" : "zl", "age" : 33, "no" : "03130321" }{ "_id" : ObjectId("59cdf6815f77c2c6c7f327ae"), "name" : "test0", "id" : 0 }{ "_id" : ObjectId("59cdf6815f77c2c6c7f327af"), "name" : "test1", "id" : 1 }{ "_id" : ObjectId("59cdf6815f77c2c6c7f327b0"), "name" : "test2", "id" : 2 }

db.zltest.find({name:{$in:["zl"]}})
{ "_id" : ObjectId("59cb36db25238f9e9cb9774f"), "name" : "zl", "age" : 33, "no" : "03130321" }

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原始发表：2026-06-17，如有侵权请联系 cloudcommunity@tencent.com 删除

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