Mongodb (compare relational database, cloud database, common command line, tutorial)

Catalog

MongoDB

contrast RDBMS（ The term ）

Official website installation

MongoDB Cloud database

Keep database name

Common command line

help

Database operation

use dbname

show dbs

db.dropDatabase()

db.stats()

db.getMongo()

db.getName()

db.version()

Set operations

db.createCollection("collectionName")

db.getCollectionNames()

db.printCollectionStats()

file （ data ） operation

（ Insert ）db.collectionName.insert([{name:'yf',age:18},{name:'mm',age:null}])

（ lookup ）db.collectionName.find({age:{$gt:3,$lte:5}})

db.collectionName.find({$or:[{name:'yf'},{age:18}]})

db.collectionName.find({name:/^a.*c$/})

db.collectionName.find({},{name:0})

db.collectionName.find({}).sort({age:1})

db.collectionName.find().limit(3).sort({age:1})

db.collectionName.find().skip(2)

db.collectionName.find().count()

db.collectionName.distinct('name')

（ modify ）db.collectionName.update({name:'yf'},{$set:{age:16}},{upsert:true})

db.collectionName.updateMany({name:'abc'},{$inc:{age:100}})

（ Delete ）db.collectionName.remove({name:'a'},{justOne:true}) 

course

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MongoDB

A database based on distributed file storage . Products between relational and non relational databases , Non-relational databases are the most versatile , Most like a relational database .

contrast RDBMS（ The term ）

RDBMS（ Relational database management system ） And MongoDB Corresponding term ：

SQL The term / Concept	MongoDB The term / Concept	explain / explain
database	database	database
table	collection	Database table / aggregate
row	document	Data record row / file
column	field	Data field / Domain
index	index	Indexes
table joins		Table joins ,MongoDB I won't support it
primary key	primary key	Primary key ,MongoDB Automatically put _id Field sets the primary key

Through the following example , We can also see it more visually Mongo Some of the concepts in ：

Official website installation

Install MongoDB Community Edition — MongoDB Manual

MongoDB Cloud database

Cloud: MongoDB Cloud

Keep database name

By default, there is a database that can be accessed directly .

• admin： From a rights perspective , This is a "root" database . Add a user to the database , This user automatically inherits permissions for all databases . Certain server-side commands can only be run from this database , Such as listing all the databases or shutting down the server .
• local:  This data will never be copied , Can be used to store any collection limited to a single local server
• config: When Mongo Used for sharding Settings ,config The database is used internally , Used to save information about sharding .

Common command line

help

Check the command prompt .

Database operation

use dbname

Create a database named dbname（ Usually lowercase ）

show dbs

Display all databases （ If there is no set in the database, it will not be displayed use The created database will not display ）

db.dropDatabase()

Delete the current database . 

db.stats()

View the currently used database information , Including the name 、 size 、 How many sets are there .

db.getMongo()

View the address of the current database link .

db.getName()

View the database name currently in use

db.version()

Check the database version

Set operations

db.createCollection("collectionName")

Create set collectionName.

db.getCollectionNames()

View the names of all sets in the current database .

db.printCollectionStats()

View the information of all sets under the currently used database , Including the name 、 size 、 How many pieces of data .

file （ data ） operation

（ Insert ）db.collectionName.insert([{name:'yf',age:18},{name:'mm',age:null}])

stay colletionName Insert multiple pieces of data under the set （ When colletionName When the set does not exist , The collection will be created and the data will be inserted ）.

（ lookup ）db.collectionName.find({age:{ $gt:3,$lte:5}})

Show colletionName Gather all age Greater than 3 Less than or equal to 5 The data of . When not writing , To display all data .$gt Greater than ,$lt Say less than ,$gte Is greater than or equal to ,$lte Less than or equal to .

db.collectionName.find({$or:[{name:'yf'},{age:18}]})

Show colletionName Set below name:'yf' perhaps age:18 The data of .

db.collectionName.find({name:/^a.*c$/})

Show colletionName Gather all name With a Begin with c Data at the end .

db.collectionName.find({},{name:0})

Show colletionName Set all data under ,name Field not displayed .

db.collectionName.find({}).sort({age:1})

Show colletionName Collect all the data and follow age In ascending order ,-1 Representation of descending order , The default is 0 Don't order .

db.collectionName.find().limit(3).sort({age:1})

Show colletionName Set according to age The first three data after the ascending order of （ Be careful sort Write limit Before or after sorting, data is retrieved ）.

db.collectionName.find().skip(2)

Skip the former 2 Data , Show colletionName Gather all other data .

db.collectionName.find().count()

Show colletionName How many pieces of data are there in the set .

db.collectionName.distinct('name')

Show colletionName Gather all name Corresponding value （ duplicate removal After ）.

（ modify ）db.collectionName.update({name:'yf'},{$set:{age:16}},{upsert:true})

take colletionName Gather the first name:'yf' The data of age Set to 16,upsert:true It means to create a piece of data if it is not found （ This parameter cannot be written , The default is false）.

db.collectionName.updateMany({name:'abc'},{$inc:{age:100}})

take colletionName Gather all name:'abc' The data of age increase 16.

（ Delete ）db.collectionName.remove({name:'a'},{justOne:true}) 

take colletionName Gather the first name:'a' Data deletion ,justOne:true Indicates that only one （ The default is false, Optional ）.

course

MongoDB course | Novice tutorial