MongoDB的基本操作

使用 insert 完成插入操作

操作格式: db.<集合>.insertOne(<json对象>) db.<集合>.insertMany([, , …])

> db.fruit.insertOne({name: "apple"})  插入的语句
返回信息
{
	"acknowledged" : true,
	"insertedId" : ObjectId("5e980a7e05d499f414a4e839")
}

>db.fruit.insertMany([
    {name: "apple"},
    {name: "pear"},
    {name: "orange"}
... ])  插入的语句
返回信息
  
{
	"acknowledged" : true,
	"insertedIds" : [
		ObjectId("5e980a8205d499f414a4e83a"),
		ObjectId("5e980a8205d499f414a4e83b"),
		ObjectId("5e980a8205d499f414a4e83c")
	]
}

  查看插入的数据

> db.fruit.find()
{ "_id" : ObjectId("5e980a7e05d499f414a4e839"), "name" : "apple" }
{ "_id" : ObjectId("5e980a8205d499f414a4e83a"), "name" : "apple" }
{ "_id" : ObjectId("5e980a8205d499f414a4e83b"), "name" : "pear" }
{ "_id" : ObjectId("5e980a8205d499f414a4e83c"), "name" : "orange" }
{ "_id" : ObjectId("5e980a8b05d499f414a4e83d"), "name" : "apple" }

  关于 find: find 是 MongoDB 中查询数据的基本指令,相当于 SQL 中的 SELECT 。 find 返回的是游标

find 示例:

db.fruit.find( { "name" : "apple" } )   #只有一个条件的查询
{ "_id" : ObjectId("5e980a7e05d499f414a4e839"), "name" : "apple" }
{ "_id" : ObjectId("5e980a8205d499f414a4e83a"), "name" : "apple" }
{ "_id" : ObjectId("5e980a8b05d499f414a4e83d"), "name" : "apple" }
> db.fruit.find( { "name" : "apple","_id" : ObjectId("5e980a8b05d499f414a4e83d") } )    #多条件并存and
{ "_id" : ObjectId("5e980a8b05d499f414a4e83d"), "name" : "apple" }
>db.fruit.find( {$and:[{"name" : "apple"},{"_id" : ObjectId("5e980a8b05d499f414a4e83d")}] } ) #多添加并存(都满足)and,另一种写法
{ "_id" : ObjectId("5e980a8b05d499f414a4e83d"), "name" : "apple" }
 db.fruit.find( {$or:[{"name" : "apple"},{"_id" : ObjectId("5e980a8205d499f414a4e83c")}] } )  #or多条件只满足一个条件即可
{ "_id" : ObjectId("5e980a7e05d499f414a4e839"), "name" : "apple" }
{ "_id" : ObjectId("5e980a8205d499f414a4e83a"), "name" : "apple" }
{ "_id" : ObjectId("5e980a8205d499f414a4e83c"), "name" : "orange" }
{ "_id" : ObjectId("5e980a8b05d499f414a4e83d"), "name" : "apple" }
> db.fruit.find({"name" : /^o/ } )   这则匹配
{ "_id" : ObjectId("5e980a8205d499f414a4e83c"), "name" : "orange" }

  查询条件对照表

SOL mol
a = 1 {a: 1}
a <> 1 {a: {$ne: 1}}
a > 1 {a: {$gt: 1}}
a >= 1 {a: {$gte: 1}}
a < 1 {a: {$lt: 1}}
a <= 1 {a: {$lte: 1}}
a = 1 AND b = 1 {a: 1, b: 1}或{$and: [{a: 1}, {b: 1}]}
a = 1 OR b = 1 {$or: [{a: 1}, {b: 1}]}
a IS NULL {a: {$exists: false}}
a IN (1, 2, 3) {a: {$in: [1, 2, 3]}}

 

查询逻辑运算符

● $lt: 存在并小于

● $lte: 存在并小于等于

● $gt: 存在并大于

● $gte: 存在并大于等于

● $ne: 不存在或存在但不等于

● $in: 存在并在指定数组中

● $nin: 不存在或不在指定数组中

● $or: 匹配两个或多个条件中的一个

● $and: 匹配全部条件

使用 find 搜索子文档

> db.fruit.drop()   #删除操作
true
> db.fruit.insertOne({
... name: "apple",
... from: {
... country: "China",
... province: "Guangdon"
... }
... })   重新插入
返回的信息
{
	"acknowledged" : true,
	"insertedId" : ObjectId("5e99090d05d499f414a4e83e")
}

  考虑以下查询的意义:

>db.fruit.find( { "from.country" : "China" } )  语句表示查询一个子文档from.country
返回
{ "_id" : ObjectId("5e99090d05d499f414a4e83e"), "name" : "apple", "from" : { "country" : "China", "province" : "Guangdon" } }
> db.fruit.find( { "from" : {country: "China"} } )语句表示我要找from而且值是{country: "China"} 
无返回  

  使用find搜索数据

> db.fruit.insert([
... { "name" : "Apple", color: ["red", "green" ] },
... { "name" : "Mango", color: ["yellow", "green"] }
... ])   插入
返回
BulkWriteResult({
	"writeErrors" : [ ],
	"writeConcernErrors" : [ ],
	"nInserted" : 2,
	"nUpserted" : 0,
	"nMatched" : 0,
	"nModified" : 0,
	"nRemoved" : 0,
	"upserted" : [ ]
})
> db.fruit.find({color: "red"})   # color值包含red
{ "_id" : ObjectId("5e990b9305d499f414a4e83f"), "name" : "Apple", "color" : [ "red", "green" ] }
{ "_id" : ObjectId("5e990efa05d499f414a4e841"), "name" : "Apple", "color" : [ "red", "green" ] }
> db.fruit.find({$or: [{color: "red"}, {color: "yellow"}]} )   或的关系也是包含
{ "_id" : ObjectId("5e990b9305d499f414a4e83f"), "name" : "Apple", "color" : [ "red", "green" ] }
{ "_id" : ObjectId("5e990b9305d499f414a4e840"), "name" : "Mango", "color" : [ "yellow", "green" ] }
{ "_id" : ObjectId("5e990efa05d499f414a4e841"), "name" : "Apple", "color" : [ "red", "green" ] }
{ "_id" : ObjectId("5e990efa05d499f414a4e842"), "name" : "Mango", "color" : [ "yellow", "green" ] }

使用 find 搜索数组中的对象

> db.movies.insertOne( {
 "title" : "Raiders of the Lost Ark",
 "filming_locations" : [
 { "city" : "Los Angeles", "state" : "CA", "country" : "USA" },
 { "city" : "Rome", "state" : "Lazio", "country" : "Italy" },
{ "city" : "Florence", "state" : "SC", "country" : "USA" } ] }) 语句 返回 { "acknowledged" : true, "insertedId" : ObjectId("5e9910fa05d499f414a4e843") }

// 查找城市是 Rome 的记录

db.movies.find({"filming_locations.city": "Rome"})
{ "_id" : ObjectId("5e9910fa05d499f414a4e843"), "title" : "Raiders of the Lost Ark", "filming_locations" : [ { "city" : "Los Angeles", "state" : "CA", "country" : "USA" }, { "city" : "Rome", 
"state" : "Lazio", "country" : "Italy" }, { "city" : "Florence", "state" : "SC", "country" : "USA" } ] }

  使用 find 搜索数组中的对象在数组中搜索子对象的多个字段时,如果使用 $elemMatch,它表示必须是同一个 子对象满足多个条件。考虑以下两个查询:

> db.getCollection('movies').find({
 "filming_locations.city": "Rome",
 "filming_locations.country": "USA"
})  去重查询语句
返回
{ "_id" : ObjectId("5e9910fa05d499f414a4e843"), "title" : "Raiders of the Lost Ark", "filming_locations" : [ { "city" : "Los Angeles", "state" : "CA", "country" : "USA" }, { "city" : "Rome", 
"state" : "Lazio", "country" : "Italy" }, { "city" : "Florence", "state" : "SC", "country" : "USA" } ] }

  控制 find 返回的字段 ● find 可以指定只返回指定的字段; ● _id字段必须明确指明不返回,否则默认返回; ● 在 MongoDB 中我们称这为投影(projection);

> db.movies.find({},{"_id":0, title:1})#0表示不显示1表示显示
返回
{ "title" : "Raiders of the Lost Ark" }

db.movies.find().pretty()与db.movies.find()的区别

> db.movies.find().pretty()
查询返回
{
	"_id" : ObjectId("5e9910fa05d499f414a4e843"),
	"title" : "Raiders of the Lost Ark",
	"filming_locations" : [
		{
			"city" : "Los Angeles",
			"state" : "CA",
			"country" : "USA"
		},
		{
			"city" : "Rome",
			"state" : "Lazio",
			"country" : "Italy"
		},
		{
			"city" : "Florence",
			"state" : "SC",
			"country" : "USA"
		}
	]
}
> db.movies.find()
查询返回
{ "_id" : ObjectId("5e9910fa05d499f414a4e843"), "title" : "Raiders of the Lost Ark", "filming_locations" : [ { "city" : "Los Angeles", "state" : "CA", "country" : "USA" }, { "city" : "Rome", 
"state" : "Lazio", "country" : "Italy" }, { "city" : "Florence", "state" : "SC", "country" : "USA" } ] }

使用 remove 删除文档

remove 命令需要配合查询条件使用;

匹配查询条件的的文档会被删除; 

指定一个空文档条件会删除所有文档;

db.testcol.remove( { a : 1 } ) // 删除a 等于1的记录
db.testcol.remove( { a : { $lt : 5 } } ) // 删除a 小于5的记录
db.testcol.remove( { } ) // 删除所有记录
db.testcol.remove() //报错

使用 update 更新文档

Update 操作执行格式:db.<集合>.update(<查询条件>, <更新字段>)

> db.fruit.insertMany([
 {name: "apple"},
{name: "pear"},
{name: "orange"}
 ]) 语句
返回
{
	"acknowledged" : true,
	"insertedIds" : [
		ObjectId("5e9917fe05d499f414a4e847"),
		ObjectId("5e9917fe05d499f414a4e848"),
		ObjectId("5e9917fe05d499f414a4e849")
	]
}
> 
> db.fruit.find()  查看
{ "_id" : ObjectId("5e9917fe05d499f414a4e847"), "name" : "apple" }
{ "_id" : ObjectId("5e9917fe05d499f414a4e848"), "name" : "pear" }
{ "_id" : ObjectId("5e9917fe05d499f414a4e849"), "name" : "orange" }
> db.fruit.updateOne({name: "apple"}, {$set: {from: "China"}})更新添加查询 name 为apple 的记录;将找到添加的 from设置为 China
{ "acknowledged" : true, "matchedCount" : 1, "modifiedCount" : 1 }
> db.fruit.find() 查看
{ "_id" : ObjectId("5e9917fe05d499f414a4e847"), "name" : "apple", "from" : "China" }
{ "_id" : ObjectId("5e9917fe05d499f414a4e848"), "name" : "pear" }
{ "_id" : ObjectId("5e9917fe05d499f414a4e849"), "name" : "orange" }

  使用 update 更新文档

● 使用 updateOne 表示无论条件匹配多少条记录,始终只更新第一条;

● 使用 updateMany 表示条件匹配多少条就更新多少条;

● updateOne/updateMany 方法要求更新条件部分必须具有以下之一,否则将报错:

• $set/$unset

• $push/$pushAll/$pop

• $pull/$pullAll

• $addToSet

● // 报错 db.fruit.updateOne({name: "apple"}, {from: "China"})

使用 update 更新数组

● $push: 增加一个对象到数组底部

● $pushAll: 增加多个对象到数组底部

● $pop: 从数组底部删除一个对象

● $pull: 如果匹配指定的值,从数组中删除相应的对象

● $pullAll: 如果匹配任意的值,从数据中删除相应的对象

● $addToSet: 如果不存在则增加一个值到数组

使用 drop 删除集合

● 使用 db.<集合>.drop() 来删除一个集合

● 集合中的全部文档都会被删除

● 集合相关的索引也会被删除 db.colToBeDropped.drop()

使用 dropDatabase 删除数据库

● 使用 db.dropDatabase() 来删除数据库

● 数据库相应文件也会被删除,磁盘空间将被释放

use tempDB

db.dropDatabase()

show collections // No collections

show dbs // The db is gone

posted @ 2020-04-17 10:59  烟雨楼台,行云流水  阅读(155)  评论(0编辑  收藏  举报