MongoDB的特点：
- 高性能
- 易使用
- 易部署
- 模式自由
- 动态查询（支持js）
- BSON数据存储
- 复制和数据恢复
- 索引，分片都支持
MongoDB公司原名是10gen公司，后来更名为MongoDB公司，典型的产品比公司名气大。名字来源于Humongous，目标在于处理海量的数据。
1. MongoDB的安装
- mongod 服务器启动程序
- mongo 客户端启动程序
对于类unix平台来说，可以使用命令直接安装，相对很方便！
for mac os
brew install mongodb
for ubuntu
sudo apt-get install mongodb
如果是类unix平台，推荐使用命令行安装，执行文件默认在系统可执行路径下！
2. MongoDB的增删改查
2.1 MongoDB的组织结构
MongoDB默认没有用户验证机制，使用mongo可以直接登陆，我们可以认为MongoDB的组织结构是三层！
库 - 集合(表) - 文档(记录)
2.2 启动MongoDB
- 服务器启动
/usr/local/bin/mongod -f /usr/local/etc/mongod.conf &
配置文件内容如下：
localhost:incentiveblog yk$ cat /usr/local/etc/mongod.confsystemLog: destination: file path: /usr/local/var/log/mongodb/mongo.log logAppend: truestorage: dbPath: /usr/local/var/mongodbnet: bindIp: 127.0.0.1
- 客户端连接
输入mongo就连接了
localhost:incentiveblog yk$ mongoMongoDB shell version v3.6.4connecting to: mongodb://127.0.0.1:27017MongoDB server version: 3.6.4Server has startup warnings: 2019-01-18T11:29:05.899+0800 I CONTROL [initandlisten] 2019-01-18T11:29:05.899+0800 I CONTROL [initandlisten] ** WARNING: Access control is not enabled for the database.2019-01-18T11:29:05.899+0800 I CONTROL [initandlisten] ** Read and write access to data and configuration is unrestricted.2019-01-18T11:29:05.899+0800 I CONTROL [initandlisten] 2019-01-18T11:29:05.899+0800 I CONTROL [initandlisten] 2019-01-18T11:29:05.899+0800 I CONTROL [initandlisten] ** WARNING: soft rlimits too low. Number of files is 256, should be at least 1000>
2.3 文档的增删改查
- 新增文档
语法：
db.COLLECTION.insert(JSON)
举例
> db.person.insert({name:"yekai",age:24,sex:"man"})WriteResult({ "nInserted" : 1 })> db.person.insert({name:"fuhongxue",age:"23",sex:"man"})WriteResult({ "nInserted" : 1 })> db.person.insert({name:"luxiaojia",age:22,sex:"man",info:{like:"huasheng",wuqi:"jian"}})WriteResult({ "nInserted" : 1 }) - 查询文档
语法：
db.COLLECTTION.find(COND_JSON,SHOW_JSON)
示例：
> db.person.find(){ "_id" : ObjectId("5c414aa9466f6a72a6e5196c"), "name" : "yekai", "age" : 24, "sex" : "man" }{ "_id" : ObjectId("5c414aa9466f6a72a6e5196d"), "name" : "fuhongxue", "age" : "23", "sex" : "man" }{ "_id" : ObjectId("5c414aab466f6a72a6e5196e"), "name" : "luxiaojia", "age" : 22, "sex" : "man", "info" : { "like" : "huasheng", "wuqi" : "jian" } } > db.person.find({name:"yekai"}){ "_id" : ObjectId("5c414aa9466f6a72a6e5196c"), "name" : "yekai", "age" : 24, "sex" : "man" }> db.person.find({name:"yekai"},{_id:0}){ "name" : "yekai", "age" : 24, "sex" : "man" } - 修改文档
类比关系型语法：update tablename set col= val where cond;
语法：db.COLLECTION.update(COND_JSON,UPDATE_JSON)
示例1，想把yekai的年龄修改为30
> db.person.update({name:"yekai"},{age:30})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 }) 修改后yekai消失了，结论后面的json要写全部信息。
> db.person.update({name:"yekai"},{age:30})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.person.find(){ "_id" : ObjectId("5c414aa9466f6a72a6e5196c"), "age" : 30 }{ "_id" : ObjectId("5c414aa9466f6a72a6e5196d"), "name" : "fuhongxue", "age" : "23", "sex" : "man" }{ "_id" : ObjectId("5c414aab466f6a72a6e5196e"), "name" : "luxiaojia", "age" : 22, "sex" : "man", "info" : { "like" : "huasheng", "wuqi" : "jian" } } 示例2，也可以使用$set操作符，进行精确修改
> db.person.update({name:"fuhongxue"},{$set:{age:30}})WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })> db.person.find(){ "_id" : ObjectId("5c414aa9466f6a72a6e5196c"), "age" : 30 }{ "_id" : ObjectId("5c414aa9466f6a72a6e5196d"), "name" : "fuhongxue", "age" : 30, "sex" : "man" }{ "_id" : ObjectId("5c414aab466f6a72a6e5196e"), "name" : "luxiaojia", "age" : 22, "sex" : "man", "info" : { "like" : "huasheng", "wuqi" : "jian" } } 实验证明，这样ok！
- 删除文档
语法：
db.COLLECTION.remove(COND_JSON)
示例：删除年龄是30的人
> db.person.remove({age:30})WriteResult({ "nRemoved" : 2 })> db.person.find(){ "_id" : ObjectId("5c414aab466f6a72a6e5196e"), "name" : "luxiaojia", "age" : 22, "sex" : "man", "info" : { "like" : "huasheng", "wuqi" : "jian" } } 总结：MongoDB对json非常依赖，我们只是简单的介绍了几个例子，有些更复杂的写法留给读者自学。
