Basic operations of mongodb [add, delete, modify, query]

1、 library （database） operation

 In the following example, we created a database  db1:
> use db1
switched to db db1
> db
db1
 
 If you want to view all databases , have access to  show dbs  command :
> show dbs
admin   0.000GB
config  0.000GB
local   0.000GB

 You can see , The database we just created  db1  Not in the list of databases , To display it , We need to  db1  Database inserts some data :
> db.db1.insert({_id:1,test:"hello MongoDB"})
WriteResult({ "nInserted" : 1 })
> show dbs
admin   0.000GB
config  0.000GB
db1     0.000GB
local   0.000GB

 In the following example, we deleted the database  db1:
> db.dropDatabase()
{ "dropped" : "db1", "ok" : 1 }

 You can see the database  db1  No longer exists :
> show dbs
admin   0.000GB
config  0.000GB
local   0.000GB

2、 aggregate （collection） operation

 Create database  test  Prepare for subsequent tests :
> use test
switched to db test
> db
test
> db.createCollection("student")
{ "ok" : 1 }

 In the following example, we created a set  student:
> db.createCollection("student")
{ "ok" : 1 }

 If you want to view all collections of this library , have access to  db.getCollectionNames()  command :
> db.getCollectionNames()
[ "student" ]

 Get the aggregate collection with the specified name （table）【 Personal feeling has no practical significance （ The set may not exist ）】:
> db.getCollection("student")
test.student
> db.getCollection("t1")
test.t1
// You can see above “t1” This set does not actually exist , But you can still return the aggregated set 

 Show the current db The status of all clustered indexes 
> db.printCollectionStats()

Other

 Query previous error messages 
db.getPrevError();

 Clear error records 
db.resetError();

 view help 
db.collectionName.help()

 Query the number of data in the current set 
db.collectionName.count()

 Look at the data space size 
db.collectionName.dataSize()

 Get the... Where the current aggregation set is located db
db.collectionName.getDB()

 Get the state of the current aggregation 
db.collectionName.stats()
 
 Get the aggregate total size 
db.collectionName.totalSize()

 Aggregate storage space size 
db.collectionName.storageSize()
 
Shard Version information 
db.collectionName.getShardVersion()

 Aggregate collection rename 
db.collectionName.renameCollection("newCollectionName")

 Delete the current aggregation collection 
db.collectionName.drop()

3、 file （documen） operation

1） Insert （ Add ） operation

 The following examples are given in  db1.student  Insert a document into the collection :
 Method 1 ：
> db.student.insert({id:1,name:" Zhang San ",gender:" male ",age:18})
WriteResult({ "nInserted" : 1 })

 Method 2 ：
> db.student.save({id:2,name:" Li Si ",gender:" male ",age:19})
WriteResult({ "nInserted" : 1 })

 Method 3 ：
> db.student.insertOne({id:3,name:" Wang Wu ",gender:" male ",age:18})
{
	"acknowledged" : true,
	"insertedId" : ObjectId("62986a0622e54ae6c619dde6")
}

 The following examples are given in  db1.student  Insert multiple documents into the collection :
> db.student.insertMany(
... [
... {id:4,name:" Zhao Liu ",gender:" Woman ",age:21},
... {id:5,name:" Qian Qi ",gender:" Woman ",age:20}
... ]
... )
{
	"acknowledged" : true,
	"insertedIds" : [
		ObjectId("62986bbe22e54ae6c619dde8"),
		ObjectId("62986bbe22e54ae6c619dde9")
	]
}

 The following examples are given in  db1.student  Insert multiple multidimensional documents into the collection :
> db.student.insertMany(
... [
... {id:8,name:" Sun Ba ",gender:" male ",age:19,address:{province:"guangdong",city:"guangzhou"}},
... {id:9,name:" Hou Jiu ",gender:" Woman ",age:22,address:{province:"guangxi",city:"guilin"}},
... {id:10,name:" Bear ten ",gender:" Woman ",age:18,address:{province:"fujian",city:"xiamen"}}
... ]
... )
{
	"acknowledged" : true,
	"insertedIds" : [
		ObjectId("62986d4e22e54ae6c619ddea"),
		ObjectId("62986d4e22e54ae6c619ddeb"),
		ObjectId("62986d4e22e54ae6c619ddec")
	]
}

 The following examples are given in  db1.student  Insert multiple multidimensional array documents into the collection :
> db.student.insertMany(
... [
... {id:11,name:" Wu Jing ",gender:" male ",age:43,address:{province:"beijing",city:"beijing"},hobby:["mil","fight","sing"]},
... {id:12,name:" Yang Mi ",gender:" Woman ",age:31,address:{province:"hongkong",city:"hongkong"},hobby:["dance","shopping","sing"]},
... {id:13,name:" Huang Bo ",gender:" male ",age:45,address:{province:"shandong",city:"qingdao"},hobby:["dance","game","sing"]}
... ]
... )
{
	"acknowledged" : true,
	"insertedIds" : [
		ObjectId("62986f8322e54ae6c619dded"),
		ObjectId("62986f8322e54ae6c619ddee"),
		ObjectId("62986f8322e54ae6c619ddef")
	]
}

2） Query operation

 Query all documents ：
> db.student.find()
{ "_id" : ObjectId("6298694722e54ae6c619dde4"), "id" : 1, "name" : " Zhang San ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("629869de22e54ae6c619dde5"), "id" : 2, "name" : " Li Si ", "gender" : " male ", "age" : 19 }
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde8"), "id" : 4, "name" : " Zhao Liu ", "gender" : " Woman ", "age" : 21 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde9"), "id" : 5, "name" : " Qian Qi ", "gender" : " Woman ", "age" : 20 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddea"), "id" : 6, "name" : " Sun Ba ", "gender" : " male ", "age" : 19, "address" : { "province" : "guangdong", "city" : "guangzhou" } }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddeb"), "id" : 7, "name" : " Hou Jiu ", "gender" : " Woman ", "age" : 22, "address" : { "province" : "guangxi", "city" : "guilin" } }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddec"), "id" : 8, "name" : " Bear ten ", "gender" : " Woman ", "age" : 18, "address" : { "province" : "fujian", "city" : "xiamen" } }
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 9, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "id" : 10, "name" : " Yang Mi ", "gender" : " Woman ", "age" : 31, "address" : { "province" : "hongkong", "city" : "hongkong" }, "hobby" : [ "dance", "shopping", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddef"), "id" : 11, "name" : " Huang Bo ", "gender" : " male ", "age" : 45, "address" : { "province" : "shandong", "city" : "qingdao" }, "hobby" : [ "dance", "game", "sing" ] }

 Query all documents （ After beautification ）：
> db.student.find().pretty()
{
	"_id" : ObjectId("6298694722e54ae6c619dde4"),
	"id" : 1,
	"name" : " Zhang San ",
	"gender" : " male ",
	"age" : 18
}
{
	"_id" : ObjectId("629869de22e54ae6c619dde5"),
	"id" : 2,
	"name" : " Li Si ",
	"gender" : " male ",
	"age" : 19
}
{
	"_id" : ObjectId("62986a0622e54ae6c619dde6"),
	"id" : 3,
	"name" : " Wang Wu ",
	"gender" : " male ",
	"age" : 18
}
{
	"_id" : ObjectId("62986bbe22e54ae6c619dde8"),
	"id" : 4,
	"name" : " Zhao Liu ",
	"gender" : " Woman ",
	"age" : 21
}
{
	"_id" : ObjectId("62986bbe22e54ae6c619dde9"),
	"id" : 5,
	"name" : " Qian Qi ",
	"gender" : " Woman ",
	"age" : 20
}
{
	"_id" : ObjectId("62986d4e22e54ae6c619ddea"),
	"id" : 6,
	"name" : " Sun Ba ",
	"gender" : " male ",
	"age" : 19,
	"address" : {
		"province" : "guangdong",
		"city" : "guangzhou"
	}
}
{
	"_id" : ObjectId("62986d4e22e54ae6c619ddeb"),
	"id" : 7,
	"name" : " Hou Jiu ",
	"gender" : " Woman ",
	"age" : 22,
	"address" : {
		"province" : "guangxi",
		"city" : "guilin"
	}
}
{
	"_id" : ObjectId("62986d4e22e54ae6c619ddec"),
	"id" : 8,
	"name" : " Bear ten ",
	"gender" : " Woman ",
	"age" : 18,
	"address" : {
		"province" : "fujian",
		"city" : "xiamen"
	}
}
{
	"_id" : ObjectId("62986f8322e54ae6c619dded"),
	"id" : 9,
	"name" : " Wu Jing ",
	"gender" : " male ",
	"age" : 43,
	"address" : {
		"province" : "beijing",
		"city" : "beijing"
	},
	"hobby" : [
		"mil",
		"fight",
		"sing"
	]
}
{
	"_id" : ObjectId("62986f8322e54ae6c619ddee"),
	"id" : 10,
	"name" : " Yang Mi ",
	"gender" : " Woman ",
	"age" : 31,
	"address" : {
		"province" : "hongkong",
		"city" : "hongkong"
	},
	"hobby" : [
		"dance",
		"shopping",
		"sing"
	]
}
{
	"_id" : ObjectId("62986f8322e54ae6c619ddef"),
	"id" : 11,
	"name" : " Huang Bo ",
	"gender" : " male ",
	"age" : 45,
	"address" : {
		"province" : "shandong",
		"city" : "qingdao"
	},
	"hobby" : [
		"dance",
		"game",
		"sing"
	]
}

 Query a document （ Support specifying ）：
> db.student.findOne()
{
	"_id" : ObjectId("6298694722e54ae6c619dde4"),
	"id" : 1,
	"name" : " Zhang San ",
	"gender" : " male ",
	"age" : 18
}
> db.student.findOne({id:5})
{
	"_id" : ObjectId("62986bbe22e54ae6c619dde9"),
	"id" : 5,
	"name" : " Qian Qi ",
	"gender" : " Woman ",
	"age" : 20
}

> db.student.find({id:3})
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male ", "age" : 18 }

 Query all documents ：
> db.student.find()
{ "_id" : ObjectId("6298694722e54ae6c619dde4"), "id" : 1, "name" : " Zhang San ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("629869de22e54ae6c619dde5"), "id" : 2, "name" : " Li Si ", "gender" : " male ", "age" : 19 }
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde8"), "id" : 4, "name" : " Zhao Liu ", "gender" : " Woman ", "age" : 21 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde9"), "id" : 5, "name" : " Qian Qi ", "gender" : " Woman ", "age" : 20 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddea"), "id" : 8, "name" : " Sun Ba ", "gender" : " male ", "age" : 19, "address" : { "province" : "guangdong", "city" : "guangzhou" } }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddeb"), "id" : 9, "name" : " Hou Jiu ", "gender" : " Woman ", "age" : 22, "address" : { "province" : "guangxi", "city" : "guilin" } }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddec"), "id" : 10, "name" : " Bear ten ", "gender" : " Woman ", "age" : 18, "address" : { "province" : "fujian", "city" : "xiamen" } }
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "id" : 12, "name" : " Yang Mi ", "gender" : " Woman ", "age" : 31, "address" : { "province" : "hongkong", "city" : "hongkong" }, "hobby" : [ "dance", "shopping", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddef"), "id" : 13, "name" : " Huang Bo ", "gender" : " male ", "age" : 45, "address" : { "province" : "shandong", "city" : "qingdao" }, "hobby" : [ "dance", "game", "sing" ] }

 Range condition query :
$gt 	 Greater than 
$lt 	 Say less than 
$gte 	 Is greater than or equal to 
$lte 	 Less than or equal to 

 Format :
 operation  	 		 Format 
 be equal to  	 		{
   <key>:<value>}
 Less than  	 		{
   <key>:{$lt:<value>}}
 Less than or equal to  		{
   <key>:{$lte:<value>}}
 Greater than  	 		{
   <key>:{$gt:<value>}}
 Greater than or equal to  		{
   <key>:{$gte:<value>}}
 It's not equal to  			{
   <key>:{$ne:<value>}}

 Example :
 Query age is greater than 40 year 
> db.student.find({age:{$gt:30}})
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "id" : 12, "name" : " Yang Mi ", "gender" : " Woman ", "age" : 31, "address" : { "province" : "hongkong", "city" : "hongkong" }, "hobby" : [ "dance", "shopping", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddef"), "id" : 13, "name" : " Huang Bo ", "gender" : " male ", "age" : 45, "address" : { "province" : "shandong", "city" : "qingdao" }, "hobby" : [ "dance", "game", "sing" ] }

 Multiconditional query :
AND 		db. Data sheet .find({ Conditions , Conditions , Conditions })
OR 			 Conditional statements use keywords  
$or Grammar format :
db. Data sheet .find({$or:[{ Conditions },{ Conditions },{ Conditions }]})

 Example :
 Query age is greater than or equal to 20 Less than or equal to 30 year 
> db.student.find({age:{$gte:20,$lte:30}})
{ "_id" : ObjectId("62986bbe22e54ae6c619dde8"), "id" : 4, "name" : " Zhao Liu ", "gender" : " Woman ", "age" : 21 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde9"), "id" : 5, "name" : " Qian Qi ", "gender" : " Woman ", "age" : 20 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddeb"), "id" : 9, "name" : " Hou Jiu ", "gender" : " Woman ", "age" : 22, "address" : { "province" : "guangxi", "city" : "guilin" } }

 regular expression :

 Check the data of last name 
> db.student.find({name:/^ king /})
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male ", "age" : 18 }

 Check the data with Jing in the name 
> db.student.find({name:/ Beijing /})
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }

 Query specified column name、age data （ List only name & age, Other omissions ）:
> db.student.find({},{name:1,age:1})
{ "_id" : ObjectId("6298694722e54ae6c619dde4"), "name" : " Zhang San ", "age" : 18 }
{ "_id" : ObjectId("629869de22e54ae6c619dde5"), "name" : " Li Si ", "age" : 19 }
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "name" : " Wang Wu ", "age" : 18 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde8"), "name" : " Zhao Liu ", "age" : 21 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde9"), "name" : " Qian Qi ", "age" : 20 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddea"), "name" : " Sun Ba ", "age" : 19 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddeb"), "name" : " Hou Jiu ", "age" : 22 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddec"), "name" : " Bear ten ", "age" : 18 }
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "name" : " Wu Jing ", "age" : 43 }
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "name" : " Yang Mi ", "age" : 31 }
{ "_id" : ObjectId("62986f8322e54ae6c619ddef"), "name" : " Huang Bo ", "age" : 45 }

 Show _id, No display name、age、address Column :
> db.student.find({},{_id:1,name:0,age:0,address:0})
{ "_id" : ObjectId("6298694722e54ae6c619dde4"), "id" : 1, "gender" : " male " }
{ "_id" : ObjectId("629869de22e54ae6c619dde5"), "id" : 2, "gender" : " male " }
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "gender" : " male " }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde8"), "id" : 4, "gender" : " Woman " }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde9"), "id" : 5, "gender" : " Woman " }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddea"), "id" : 8, "gender" : " male " }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddeb"), "id" : 9, "gender" : " Woman " }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddec"), "id" : 10, "gender" : " Woman " }
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "gender" : " male ", "hobby" : [ "mil", "fight", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "id" : 12, "gender" : " Woman ", "hobby" : [ "dance", "shopping", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddef"), "id" : 13, "gender" : " male ", "hobby" : [ "dance", "game", "sing" ] }

 No display address Column :
> db.student.find({},{address:0})
{ "_id" : ObjectId("6298694722e54ae6c619dde4"), "id" : 1, "name" : " Zhang San ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("629869de22e54ae6c619dde5"), "id" : 2, "name" : " Li Si ", "gender" : " male ", "age" : 19 }
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde8"), "id" : 4, "name" : " Zhao Liu ", "gender" : " Woman ", "age" : 21 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde9"), "id" : 5, "name" : " Qian Qi ", "gender" : " Woman ", "age" : 20 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddea"), "id" : 8, "name" : " Sun Ba ", "gender" : " male ", "age" : 19 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddeb"), "id" : 9, "name" : " Hou Jiu ", "gender" : " Woman ", "age" : 22 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddec"), "id" : 10, "name" : " Bear ten ", "gender" : " Woman ", "age" : 18 }
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "hobby" : [ "mil", "fight", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "id" : 12, "name" : " Yang Mi ", "gender" : " Woman ", "age" : 31, "hobby" : [ "dance", "shopping", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddef"), "id" : 13, "name" : " Huang Bo ", "gender" : " male ", "age" : 45, "hobby" : [ "dance", "game", "sing" ] }

 No display _id Column （ notes ：_id Columns are automatically generated , You can also specify it yourself ）:
> db.student.find({},{_id:0,name:1,age:1})
{ "name" : " Zhang San ", "age" : 18 }
{ "name" : " Li Si ", "age" : 19 }
{ "name" : " Wang Wu ", "age" : 18 }
{ "name" : " Zhao Liu ", "age" : 21 }
{ "name" : " Qian Qi ", "age" : 20 }
{ "name" : " Sun Ba ", "age" : 19 }
{ "name" : " Hou Jiu ", "age" : 22 }
{ "name" : " Bear ten ", "age" : 18 }
{ "name" : " Wu Jing ", "age" : 43 }
{ "name" : " Yang Mi ", "age" : 31 }
{ "name" : " Huang Bo ", "age" : 45 }

 notes ： In general , Or specify only those that are not displayed , Or specify only the , But only _id With the exception of （ A special case ）, You can specify 

 Sort by age :

 Ascending 
> db.student.find().sort({age:1})
{ "_id" : ObjectId("6298694722e54ae6c619dde4"), "id" : 1, "name" : " Zhang San ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddec"), "id" : 10, "name" : " Bear ten ", "gender" : " Woman ", "age" : 18, "address" : { "province" : "fujian", "city" : "xiamen" } }
{ "_id" : ObjectId("629869de22e54ae6c619dde5"), "id" : 2, "name" : " Li Si ", "gender" : " male ", "age" : 19 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddea"), "id" : 8, "name" : " Sun Ba ", "gender" : " male ", "age" : 19, "address" : { "province" : "guangdong", "city" : "guangzhou" } }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde9"), "id" : 5, "name" : " Qian Qi ", "gender" : " Woman ", "age" : 20 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde8"), "id" : 4, "name" : " Zhao Liu ", "gender" : " Woman ", "age" : 21 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddeb"), "id" : 9, "name" : " Hou Jiu ", "gender" : " Woman ", "age" : 22, "address" : { "province" : "guangxi", "city" : "guilin" } }
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "id" : 12, "name" : " Yang Mi ", "gender" : " Woman ", "age" : 31, "address" : { "province" : "hongkong", "city" : "hongkong" }, "hobby" : [ "dance", "shopping", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddef"), "id" : 13, "name" : " Huang Bo ", "gender" : " male ", "age" : 45, "address" : { "province" : "shandong", "city" : "qingdao" }, "hobby" : [ "dance", "game", "sing" ] }

 Descending 
> db.student.find().sort({age:-1})
{ "_id" : ObjectId("62986f8322e54ae6c619ddef"), "id" : 13, "name" : " Huang Bo ", "gender" : " male ", "age" : 45, "address" : { "province" : "shandong", "city" : "qingdao" }, "hobby" : [ "dance", "game", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "id" : 12, "name" : " Yang Mi ", "gender" : " Woman ", "age" : 31, "address" : { "province" : "hongkong", "city" : "hongkong" }, "hobby" : [ "dance", "shopping", "sing" ] }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddeb"), "id" : 9, "name" : " Hou Jiu ", "gender" : " Woman ", "age" : 22, "address" : { "province" : "guangxi", "city" : "guilin" } }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde8"), "id" : 4, "name" : " Zhao Liu ", "gender" : " Woman ", "age" : 21 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde9"), "id" : 5, "name" : " Qian Qi ", "gender" : " Woman ", "age" : 20 }
{ "_id" : ObjectId("629869de22e54ae6c619dde5"), "id" : 2, "name" : " Li Si ", "gender" : " male ", "age" : 19 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddea"), "id" : 8, "name" : " Sun Ba ", "gender" : " male ", "age" : 19, "address" : { "province" : "guangdong", "city" : "guangzhou" } }
{ "_id" : ObjectId("6298694722e54ae6c619dde4"), "id" : 1, "name" : " Zhang San ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddec"), "id" : 10, "name" : " Bear ten ", "gender" : " Woman ", "age" : 18, "address" : { "province" : "fujian", "city" : "xiamen" } }

 Before query 5 Data :
> db.student.find().limit(5)
{ "_id" : ObjectId("6298694722e54ae6c619dde4"), "id" : 1, "name" : " Zhang San ", "gender" : " male " "age" : 18 }
{ "_id" : ObjectId("629869de22e54ae6c619dde5"), "id" : 2, "name" : " Li Si ", "gender" : " male " "age" : 19 }
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male " "age" : 18 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde8"), "id" : 4, "name" : " Zhao Liu ", "gender" : " Woman " "age" : 21 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde9"), "id" : 5, "name" : " Qian Qi ", "gender" : " Woman " "age" : 20 }

 Inquire about 7 Data after :
> db.student.find().skip(7)
{ "_id" : ObjectId("62986d4e22e54ae6c619ddec"), "id" : 10, "name" : " Bear ten ", "gender" : " Woman ", "age" : 18, "address" : { "province" : "fujian", "city" : "xiamen" } }
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "id" : 12, "name" : " Yang Mi ", "gender" : " Woman ", "age" : 31, "address" : { "province" : "hongkong", "city" : "hongkong" }, "hobby" : [ "dance", "shopping", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddef"), "id" : 13, "name" : " Huang Bo ", "gender" : " male ", "age" : 45, "address" : { "province" : "shandong", "city" : "qingdao" }, "hobby" : [ "dance", "game", "sing" ] }

 The query in 3-12 Data between :
> db.student.find().skip(2).limit(8)
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde8"), "id" : 4, "name" : " Zhao Liu ", "gender" : " Woman ", "age" : 21 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde9"), "id" : 5, "name" : " Qian Qi ", "gender" : " Woman ", "age" : 20 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddea"), "id" : 8, "name" : " Sun Ba ", "gender" : " male ", "age" : 19, "address" : { "province" : "guangdong", "city" : "guangzhou" } }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddeb"), "id" : 9, "name" : " Hou Jiu ", "gender" : " Woman ", "age" : 22, "address" : { "province" : "guangxi", "city" : "guilin" } }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddec"), "id" : 10, "name" : " Bear ten ", "gender" : " Woman ", "age" : 18, "address" : { "province" : "fujian", "city" : "xiamen" } }
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "id" : 12, "name" : " Yang Mi ", "gender" : " Woman ", "age" : 31, "address" : { "province" : "hongkong", "city" : "hongkong" }, "hobby" : [ "dance", "shopping", "sing" ] }

 Inquire about 20 Men under the age of :
> db.student.find({age:{$lte:20},gender:" male "})
{ "_id" : ObjectId("6298694722e54ae6c619dde4"), "id" : 1, "name" : " Zhang San ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("629869de22e54ae6c619dde5"), "id" : 2, "name" : " Li Si ", "gender" : " male ", "age" : 19 }
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddea"), "id" : 8, "name" : " Sun Ba ", "gender" : " male ", "age" : 19, "address" : { "province" : "guangdong", "city" : "guangzhou" } }

 Count the number of men :
> db.student.find({gender:" male "}).count()
6

 Multidimensional field query :
> db.student.find({
   "address.city":"beijing"})
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }

 Array condition restrictions :
> db.student.find({hobby:"fight"})
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }

> db.student.find({hobby:{$all:["dance","sing"]}})
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "id" : 12, "name" : " Yang Mi ", "gender" : " Woman ", "age" : 31, "address" : { "province" : "hongkong", "city" : "hongkong" }, "hobby" : [ "dance", "shopping", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddef"), "id" : 13, "name" : " Huang Bo ", "gender" : " male ", "age" : 45, "address" : { "province" : "shandong", "city" : "qingdao" }, "hobby" : [ "dance", "game", "sing" ] }

 Other inquiries :
$in Query the data contained 
> db.student.find({age:{$in:[18,20,21,23]}},{name:1,age:1,_id:0})
{ "name" : " Zhang San ", "age" : 18 }
{ "name" : " Wang Wu ", "age" : 18 }
{ "name" : " Zhao Liu ", "age" : 21 }
{ "name" : " Qian Qi ", "age" : 20 }
{ "name" : " Bear ten ", "age" : 18 }

$exists Determine whether the field exists 
 Query exists age Field data 
> db.student.find({age:{$exists:true}})
{ "_id" : ObjectId("6298694722e54ae6c619dde4"), "id" : 1, "name" : " Zhang San ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("629869de22e54ae6c619dde5"), "id" : 2, "name" : " Li Si ", "gender" : " male ", "age" : 19 }
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde8"), "id" : 4, "name" : " Zhao Liu ", "gender" : " Woman ", "age" : 21 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde9"), "id" : 5, "name" : " Qian Qi ", "gender" : " Woman ", "age" : 20 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddea"), "id" : 8, "name" : " Sun Ba ", "gender" : " male ", "age" : 19, "address" : { "province" : "guangdong", "city" : "guangzhou" } }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddeb"), "id" : 9, "name" : " Hou Jiu ", "gender" : " Woman ", "age" : 22, "address" : { "province" : "guangxi", "city" : "guilin" } }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddec"), "id" : 10, "name" : " Bear ten ", "gender" : " Woman ", "age" : 18, "address" : { "province" : "fujian", "city" : "xiamen" } }
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "id" : 12, "name" : " Yang Mi ", "gender" : " Woman ", "age" : 31, "address" : { "province" : "hongkong", "city" : "hongkong" }, "hobby" : [ "dance", "shopping", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddef"), "id" : 13, "name" : " Huang Bo ", "gender" : " male ", "age" : 45, "address" : { "province" : "shandong", "city" : "qingdao" }, "hobby" : [ "dance", "game", "sing" ] }

 Query does not exist age Field data 
> db.student.find({age:{$exists:false}})

$mod Modulus operation 
 The query meets age The value of the column is divided by 5 more than 3 The data of 
> db.student.find({age:{$mod:[5,3]}})
{ "_id" : ObjectId("6298694722e54ae6c619dde4"), "id" : 1, "name" : " Zhang San ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddec"), "id" : 10, "name" : " Bear ten ", "gender" : " Woman ", "age" : 18, "address" : { "province" : "fujian", "city" : "xiamen" } }
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }

$ne Not equal to operation 
 Query age age is not 18 and 20 The data of 
> db.student.find({age:{$ne:18},age:{$ne:20}})
{ "_id" : ObjectId("6298694722e54ae6c619dde4"), "id" : 1, "name" : " Zhang San ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("629869de22e54ae6c619dde5"), "id" : 2, "name" : " Li Si ", "gender" : " male ", "age" : 19 }
{ "_id" : ObjectId("62986a0622e54ae6c619dde6"), "id" : 3, "name" : " Wang Wu ", "gender" : " male ", "age" : 18 }
{ "_id" : ObjectId("62986bbe22e54ae6c619dde8"), "id" : 4, "name" : " Zhao Liu ", "gender" : " Woman ", "age" : 21 }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddea"), "id" : 8, "name" : " Sun Ba ", "gender" : " male ", "age" : 19, "address" : { "province" : "guangdong", "city" : "guangzhou" } }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddeb"), "id" : 9, "name" : " Hou Jiu ", "gender" : " Woman ", "age" : 22, "address" : { "province" : "guangxi", "city" : "guilin" } }
{ "_id" : ObjectId("62986d4e22e54ae6c619ddec"), "id" : 10, "name" : " Bear ten ", "gender" : " Woman ", "age" : 18, "address" : { "province" : "fujian", "city" : "xiamen" } }
{ "_id" : ObjectId("62986f8322e54ae6c619dded"), "id" : 11, "name" : " Wu Jing ", "gender" : " male ", "age" : 43, "address" : { "province" : "beijing", "city" : "beijing" }, "hobby" : [ "mil", "fight", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddee"), "id" : 12, "name" : " Yang Mi ", "gender" : " Woman ", "age" : 31, "address" : { "province" : "hongkong", "city" : "hongkong" }, "hobby" : [ "dance", "shopping", "sing" ] }
{ "_id" : ObjectId("62986f8322e54ae6c619ddef"), "id" : 13, "name" : " Huang Bo ", "gender" : " male ", "age" : 45, "address" : { "province" : "shandong", "city" : "qingdao" }, "hobby" : [ "dance", "game", "sing" ] }

$nin Query data not included 
> db.student.find({age:{$nin:[18,20,21,23]}},{name:1,age:1,_id:0})
{ "name" : " Li Si ", "age" : 19 }
{ "name" : " Sun Ba ", "age" : 19 }
{ "name" : " Hou Jiu ", "age" : 22 }
{ "name" : " Wu Jing ", "age" : 43 }
{ "name" : " Yang Mi ", "age" : 31 }
{ "name" : " Huang Bo ", "age" : 45 }

$size Number of array elements 
 No demo （ lazy ）

3） update operation

update()  Method to update an existing document 

 Grammar format ：
db.collection.update(
   <query>,
   <update>,
   {
     upsert: <boolean>,
     multi: <boolean>,
     writeConcern: <document>
   }
)

 Parameter description ：
• query：update Query criteria for , similar sql update In the query where hinder ;
• update：update Object and some updated operators （ Such as $,$inc...） etc. , It can also be understood as sql update In the query set hinder ;
• upsert： Optional , This parameter means , If it doesn't exist update The record of , Whether insert objNew,true Insert for , The default is false, Do not insert ;
• multi： Optional ,mongodb  The default is false, Update only the first record found , If this parameter is zero true, According to the conditions to find out all the records updated ;
• writeConcern： Optional , The level at which an exception is thrown ;

 Example ：
 take title Updated to MySQL course 
MongoDB Enterprise > db.books.find()
{ "_id" : ObjectId("599026a4124716992d85a2ed"), "title" : "MongDB course ", "price" : 75, "num" : 50 }

MongoDB Enterprise > db.books.update({
   "title" : "MongDB course "},{$set:{
   "title" : "MySQL course "}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
MongoDB Enterprise > db.books.find()
{ "_id" : ObjectId("599026a4124716992d85a2ed"), "title" : "MySQL course ", "price" : 75, "num" : 50 }

price Number plus 1
MongoDB Enterprise > db.books.update({
   "title" : "MySQL course "},{$inc:{
   "price" : 1}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
MongoDB Enterprise > db.books.find()
{ "_id" : ObjectId("599026a4124716992d85a2ed"), "title" : "MySQL course ", "price" : 76, "num" : 50 }

db. surface .update({ Conditions },{
   '$set' :{ Field : value , Field : value }})
db. surface .update({ Conditions },{ Field : value , Field : value }) 
     Yes $set Modification of ： Only modify the set fields , The other fields remain unchanged 
     No, $set Modification of ： Only modify the set fields , The fields are deleted without modification （_id With the exception of )
    
 notes ： If there is a field, modify it. If not, add a new field 

4） Delete operation

 Delete record ：db. surface .remove( Conditions )
 Delete field : db. surface update({ Conditions },{ ‘$unset’ :{ Field :1/ Field :0}})