mongodb-crud基本操作

删库

> db.dropDatabase()

创建集合（表）

> db.createCollection('a')
> db.createCollection('b')

直接插入文档，集合会自动创建

> db.c.insert({username: 'mongodb'})
> show collections

删除集合

> db.a.drop()

重命名集合

> db.b.renameCollection("bb")

插入文档

> db.fruit.insertOne({name: "apple"})
{
	"acknowledged" : true,
	"insertedId" : ObjectId("64954b7814048ce7b7db5861")
}

> db.fruit.insertMany([{name: "apple"}, {name: "pear"}, {name: "orange"}])
{
	"acknowledged" : true,
	"insertedIds" : [
		ObjectId("64954bf814048ce7b7db5862"),
		ObjectId("64954bf814048ce7b7db5863"),
		ObjectId("64954bf814048ce7b7db5864")
	]
}

> for(i=0;i<10000;i++){db.log.insert({"uid":i,"name":"mongodb","age":6,"date":new Date()}); } 

find 查找

## 查询 log 集合所有信息
> db.log.find()
> show collections

## 指定单个条件查询
> db.log.find({uid: 15})
## 指定多个条件查询，相当于 and
> db.log.find({uid: 15,age: 6})

## 指定多个条件查询，以 or 方式
> db.log.find({ $or: [{uid: 15},{uid: 16},{uid: 17}]})

MySQL 和 mongodb 条件表达式对比

MySQL	mongodb
a=1
a<>1	{a:{$ne:1}}
a>1	{a:{$gt:1}}
a>=1	{a:{$ge:1}}
a<1	{a:{$lt:1}}
a<=1	{a:{$le:1}}
a=1 and b=1	{a:1,b:1} 或 {$and:[{a:1},{b:1}]}
a=1 or b=1	{$or: [{a:1},{b:2}]}
a is null	{a:{$exists:false}}
a in (1,2,3)	{a:{$in:[1,2,3]}}

通过 find 搜索子文档

> db.fruit.find()
{ "_id" : ObjectId("64954b7814048ce7b7db5861"), "name" : "apple" }
{ "_id" : ObjectId("64956d22e8de26ee5060da9d"), "name" : "apple", "from" : { "country" : "china", "province" : "guangdong" } }
{ "_id" : ObjectId("64956e1de8de26ee5060da9e"), "name" : "apple", "color" : [ "red", "green" ] }
{ "_id" : ObjectId("64956e1de8de26ee5060da9f"), "name" : "mango", "color" : [ "yellow", "green" ] }

> db.fruit.find({"from.country": "china"})
{ "_id" : ObjectId("64956d22e8de26ee5060da9d"), "name" : "apple", "from" : { "country" : "china", "province" : "guangdong" } }

通过 find 搜索数组

> db.fruit.find({color:"red"})
{ "_id" : ObjectId("64956e1de8de26ee5060da9e"), "name" : "apple", "color" : [ "red", "green" ] }
> db.fruit.find({$or: [{color:"red"},{color:"yellow"}]})
{ "_id" : ObjectId("64956e1de8de26ee5060da9e"), "name" : "apple", "color" : [ "red", "green" ] }
{ "_id" : ObjectId("64956e1de8de26ee5060da9f"), "name" : "mango", "color" : [ "yellow", "green" ] }

通过 find 搜索数组中的对象

> db.movies.find({"filming_locations.city":"Rome"})
{ "_id" : ObjectId("64956f6ce8de26ee5060daa0"), "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" } ] }
{ "_id" : ObjectId("64964e705374a9c8332c9f7c"), "title" : "11111", "filming_locations" : [ { "city" : "bj", "state" : "CA", "country" : "CHN" }, { "city" : "Rome", "state" : "Lazio", "country" : "Italy" }, { "city" : "tlp", "state" : "SC", "country" : "USA" } ] }


> db.getCollection('movies').find({"filming_locations.city":"Rome","filming_locations.country":"USA"})
{ "_id" : ObjectId("64956f6ce8de26ee5060daa0"), "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" } ] }
{ "_id" : ObjectId("64964e705374a9c8332c9f7c"), "title" : "11111", "filming_locations" : [ { "city" : "bj", "state" : "CA", "country" : "CHN" }, { "city" : "Rome", "state" : "Lazio", "country" : "Italy" }, { "city" : "tlp", "state" : "SC", "country" : "USA" } ] }
 
> db.getCollection('movies').find({"filming_locations":{$elemMatch:{"city":"bj","country":"CHN"}}})
{ "_id" : ObjectId("64964e705374a9c8332c9f7c"), "title" : "11111", "filming_locations" : [ { "city" : "bj", "state" : "CA", "country" : "CHN" }, { "city" : "Rome", "state" : "Lazio", "country" : "Italy" }, { "city" : "tlp", "state" : "SC", "country" : "USA" } ] }

通过find 指定返回的字段

> db.movies.find({},{"_id":0, title:1})
{ "title" : "Raiders of the Lost Ark" }
{ "title" : "11111" }

_id 默认是自动返回的，需要指定不返回。

通过remove 删除文档记录

##　删除匹配条件的文档记录
> db.fruit.remove({name:"apple"})

##　删除所有的文档记录
> db.fruit.remove({})

更新文档记录

> db.fruit.updateOne({name:"apple"},{$set:{from:"usa"}})

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

$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

删除集合

> db.fruit.drop()

删除数据库

> use test
> db.dropDatabase()