Mongodb common commands of mongodb series

One 、MongoDB Basic operation

1.1、 Software environment preparation

Software environment ：

• MongoDB Server5.0.9
• Navicat15.0.28
• RoboMongo 0.9.0
• Window10 System

1.2、MongoDB Connect

MongoDB Connect , Use “username:[email protected]/dbname’” In the form of connection .
Connect to the local database server , Port is the default .

mongodb://localhost

1.3、 Create database

MongoDB Create database Syntax

use DATABASE_NAME

demo： establish test database

use test

If there is no database , Just create the database , No, connect to the specified database
View all databases , Use

show dbs

But then we use show dbs Words , Still can't see the database we created , In fact, we need to add data to the database to see
demo： towards test Insert a row of data into the database

db.test.insert({
    "name":"test"})

1.4、 Delete database

MongoDB Delete database Syntax

db.dropDatabase()

However, it is generally necessary to use use Connect to database , Then delete the guidance database
demo： Delete test database
Connect test database

use test

Delete test database

db.dropDatabase()

Delete the collection
demo： Delete test Database coll aggregate

> use test
switched to db runoob
> show tables
coll
> db.coll.drop()
true
> show tables
> 

1.5、 Inserted into the document

MongoDB The syntax of inserting a document is roughly like

db.COLLECTION_NAME.insert(document)

demo： towards test Database col Insert document in collection
Method 1

>use test
>db.col.insert({
    title: 'MongoDB', 
    description: 'MongoDB NOSQL',
    by: 'test',
    url: 'https:',
    tags: ['mongodb', 'database', 'NoSQL'],
    likes: 100
})

View the written data col aggregate

db.col.find()

Method 2
Define a document object

document=({
    title: 'MongoDB', 
     description: 'MongoDB NOSQL',
    by: 'test',
    url: 'https:',
    tags: ['mongodb', 'database', 'NoSQL'],
    likes: 100
});

perform , Will define document Object to write data

db.col.insert(document)

1.6、 The new document

save() Method
The grammar is like ：

db.collection.save(
   <document>,
   {
    
     writeConcern: <document>
   }
)

Parameter meaning

1. document : Document data .
2. writeConcern : Optional , The level at which an exception is thrown .
   demo： To replace the _id by 56064f89ade2f21f36b03136 Document data

db.col.save({
    
	"_id" : ObjectId("56064f89ade2f21f36b03136"),
    "title" : "MongoDB",
    "description": 'MongoDB NOSQL',
    "by": 'test',
    "url": 'https:',
    "tags": ['mongodb', 'database', 'NoSQL'],
    "likes": 100
})

1.7、 Update the document

Update the document operation syntax, such as ：

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

Parameter meaning ：

• 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 .

demo: to update test Database documentation
Use test database

use test

Update document action

db.col.update({
    'title':'MongoDB'},{
    $set:{
    'title':'MongoDB test'}})

Then check whether the document is updated

db.col.find()

Modify multiple identical documents
The appeal situation is to modify a document , If you modify multiple identical documents , You need to set multi Parameter is true.

db.col.update({
    'title':'MongoDB'},{
    $set:{
    'title':'MongoDB test'}},{
    multi:true})

You can also use updateMulti

db.col.updateMany({
    'title':'MongoDB'},{
    $set:{
    'title':'MongoDB test'}})

Comprehensive operation ：

 Only the first record is updated ：
db.col.update( {
     "count" : {
     $gt : 1 } } , {
     $set : {
     "test2" : "OK"} } );
 All updates ：
db.col.update( {
     "count" : {
     $gt : 3 } } , {
     $set : {
     "test2" : "OK"} },false,true );
 Just add the first one ：
db.col.update( {
     "count" : {
     $gt : 4 } } , {
     $set : {
     "test5" : "OK"} },true,false );
 Add all in :
db.col.update( {
     "count" : {
     $gt : 5 } } , {
     $set : {
     "test5" : "OK"} },true,true );
 All updates ：
db.col.update( {
     "count" : {
     $gt : 15 } } , {
     $inc : {
     "count" : 1} },false,true );
 Only the first record is updated ：
db.col.update( {
     "count" : {
     $gt : 10 } } , {
     $inc : {
     "count" : 1} },false,false );

1.8、 Delete the document

MongoDB Delete the document as

db.collection.remove(
   <query>,
   <justOne>
)

MongoDB2.6 The operation of later versions is

db.collection.remove(
   <query>,
   {
    
     justOne: <boolean>,
     writeConcern: <document>
   }
)

• query :（ Optional ） Conditions for deleted documents .
• justOne : （ Optional ） If it is set to true or 1, Only one document is deleted .
• writeConcern :（ Optional ） The level at which an exception is thrown .

demo: Delete title by MongoDB The data of

db.col.remove({
    'title':'MongoDB'})

Delete all data in the collection

db.col.remove({
    })

1.9、MongoDB Inquire about

MongoDB The query syntax

db.collection.find(query, projection)

• query ： Optional , Use the query operator to specify the query criteria
• projection ： Optional , Use the projection operator to specify the returned key . Returns all key values in the document when queried , Simply omit the parameter （ The default is omitted ）.
  Easy to read query

db.col.find().pretty()

except find() Out of the way , One more findOne() Method , It returns only one document .

1.10、MongoDB Conditional operation

MongoDB AND Conditions

Multiple keys can be passed in (key), Each key (key) Separated by commas

db.col.find({
    key1:value1, key2:value2}).pretty()

Use and and in Example , obtain "col" A series of data in a set ：

db.getCollection("col").find({
    $and: [{
        "SYNC_STATUS": "HANDLED"
    }, {
        "CODE": {
            $in: [
                "123456789",
                "12345678910"
            ]
        }
    }]
}).pretty();

MongoDB OR Conditions

db.col.find(
   {
    
      $or: [
	     {
    key1: value1}, {
    key2:value2}
      ]
   }
).pretty()

MongoDB AND and OR The joint query
AND and OR A combination of , Similar to the conventional SQL Statement for ： ‘where likes>50 AND (by = ‘ course ’ OR title = ‘MongoDB course ’)’

MongoDB Conditional operators

• (>) Greater than ： $gt
• (<) Less than ： $lt
• (>=) Greater than or equal to ： $gte
• (<= ) Less than or equal to ： $lte
  Demo：
  obtain “col” Collection “likes” Greater than 100 The data of , You can use the following command ：

db.col.find({
    "likes" : {
    $gt : 100}})

obtain "col" Collection “likes” Greater than or equal to 100 The data of , You can use the following command

db.col.find({
    likes : {
    $gte : 100}})

obtain "col" Collection “likes” Less than 150 The data of , You can use the following command ：

db.col.find({
    likes : {
    $lt : 150}})

obtain "col" Collection “likes” Less than or equal to 150 The data of , You can use the following command ：

db.col.find({
    likes : {
    $lte : 150}})

obtain "col" Collection “likes” Greater than 100, Less than 200 The data of , You can use the following command ：

db.col.find({
    likes : {
    $lt :200, $gt : 100}})

MongoDB Limit and Skip The operator
Limit The operator ,Number Indicates the number of records read

db.COLLECTION_NAME.find().limit(NUMBER)

MongoDB skip() Method
Number Indicates the number of records to skip , The default from the 0 Start

db.COLLECTION_NAME.find().limit(NUMBER).skip(NUMBER)

1.11、MongoDB $type The operator

MongoDB $type Operator table

type	Numbers	remarks
Double	1
Object	2
Array	4
Binary data	5
Undefined	6	obsolete
Object id	7
Boolean	8
Date	9
Null	10
Regular Expression	11
JavaScript	13
Symbol	14
JavaScript (with scope)	15
32-bit integer	16
Timestamp	17
64-bit integer	18
Min key	255	Query with -1
Max key	127

obtain “col” Collection title by String The data of , You can use the following command ：

db.col.find({
    "title" : {
    $type : 2}})

1.12、MongoDB Sort

Use sort() Method to sort the data ,sort() Method can be used to specify the sorting field by parameter , And use 1 and -1 To specify how to sort , among 1 Arrange... In ascending order , and -1 It's for descending order .
This is to sort the set

db.COLLECTION_NAME.find().sort({
    KEY:1})

1.13、MongoDB Indexes

An index is a special data structure , The index is stored in a collection of data that is easy to read through , An index is a structure that sorts the values of a column or columns in a database table . Indexing can improve query speed . If there is no index ,MongoDB When the data is read, each file in the collection must be scanned and those records that meet the query criteria must be selected .
demo： Inquire about col aggregate ,“title” For index fields ,1 Creates an index in ascending order for the specified , If you want to create the index in descending order specify as -1 that will do .

db.col.ensureIndex({
    "title":1})

Create indexes in the background

db.values.ensureIndex({
    open: 1, close: 1}, {
    background: true})

1.14、MongoDB polymerization

MongoDB Middle polymerization (aggregate) It's mainly used to process data ( Such as the statistical average , Make a peace, etc ), And return the calculated data result . It's kind of similar sql Statement count(*).
Basic grammar such as ：

db.COLLECTION_NAME.aggregate(AGGREGATE_OPERATION)

demo： Count the number of articles written by each author through the collection , Use aggregate() The calculation results are as follows ：

db.mycol.aggregate([{
    $group : {
    _id : "$by_user", num_tutorial : {
    $sum : 1}}}])

The above example is similar to sql sentence ：
select by_user, count(*) from mycol group by by_user