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MongoDB 基本用法

 2 years ago
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MongoDB 基本用法

记得最早使用的数据库就是MongoDB，当时懵懂无知，就知道需要用一个数据库去储存数据，也分不清SQL 和 NoSQL。不过MongoDB以它的方便快捷吸引了我，以至于后来每次用MySQL的时候，还奇怪为啥每次都需要DDL定义结构，好麻烦。

P.S. 还记得学完MongoDB的那个晚上，黄昏🌆还是蛮好看的样子

# 安装教程

# 基础命令

参考教程推荐：CRUD Guides: Create, Read, Update, and Delete Data

# 数据库&集合

use test # 切换数据库
show dbs # 显示所有数据库
show collections # 显示所有collections

db.dropDatabase(test) # 删除数据库 test
db.createCollection(inventory) # 创建集合 inventory
db.inventory.drop() # 删除集合 inventory


mongo mongodb://$[hostlist]/$[database]?authSource=$[authSource] --username $[username] # 连接数据库
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# 查询文档

# 查询全量数据
db.inventory.find({}) 

# 带Query的查询
db.inventory.find( { size: { h: 14, w: 21, uom: "cm" } } ) 
db.inventory.find( { "size.uom": "in" } ) # 使用 dot notation

# 带比较运算符的查询
db.inventory.find( { "size.h": { $lt: 15 } } )

# 带And的查询
db.inventory.find( { $and: [ { price: { $ne: 1.99 } }, { price: { $exists: true } } ] } )  # 显式写法
db.inventory.find( { price: { $ne: 1.99, $exists: true } } )  # 隐式写法

# 带Or的查询
db.inventory.find( { $or: [ { status: "A" }, { qty: { $lt: 30 } } ] } )


# 复杂查询
# AND 和 OR 一起使用
db.inventory.find( {
    $and: [
        { $or: [ { qty: { $lt : 10 } }, { qty : { $gt: 50 } } ] },
        { $or: [ { sale: true }, { price : { $lt : 5 } } ] }
    ]
} )


db.inventory.find( {
     status: "A",
     $or: [ { qty: { $lt: 30 } }, { item: /^p/ } ]  // qty小于30 或 item 以 p 开头
} 

# 输出格式化
db.inventory.find({}).pretty()
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# 插入文档

# use test
# 将数据插入collections：inventory，此时会创建test数据库
# 插入一条数据
db.inventory.insertOne(
   { "item" : "canvas",
     "qty" : 100,
     "tags" : ["cotton"],
     "size" : { "h" : 28, "w" : 35.5, "uom" : "cm" }
   }
)

# 批量插入数据
db.inventory.insertMany( [
   { "item": "journal", "qty": 25, "size": { "h": 14, "w": 21, "uom": "cm" }, "status": "A" },
   { "item": "notebook", "qty": 50, "size": { "h": 8.5, "w": 11, "uom": "in" }, "status": "A" },
   { "item": "paper", "qty": 100, "size": { "h": 8.5, "w": 11, "uom": "in" }, "status": "D" },
   { "item": "planner", "qty": 75, "size": { "h": 22.85, "w": 30, "uom": "cm" }, "status": "D" },
   { "item": "postcard", "qty": 45, "size": { "h": 10, "w": 15.25, "uom": "cm" }, "status": "A" }
]);
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# 更新文档

# 更新
# 更新一条
db.inventory.updateOne(
    { "item" : "paper" }, // specifies the document to update
    {
      $set: {  "size.uom" : "cm",  "status" : "P" },
      $currentDate: { "lastModified": true }
    }
)

# 更新多条
db.inventory.updateMany(
    { "qty" : { $lt: 50 } }, // specifies the documents to update
    {
       $set: { "size.uom" : "cm", "status": "P" },
       $currentDate : { "lastModified": true }
    }
)
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# 删除文档

# 删除一条
db.inventory.deleteOne(
    { "status": "D" } // specifies the document to delete
)
# 删除多条
db.inventory.deleteMany(
    { "status" : "A" } // specifies the documents to delete
)
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# 补充

  • MongoDB中存在许多运算符，如前 $gt，Query and Projection Operators

  • 通过编程语言连接 MongoDB 文档：https://docs.mongodb.com/drivers/


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