MongoDB is one of the most popular open-source No-SQL databases. It is a document-based database. In this blog post, I will explain various MongoDB commands. We will also go over and install MongoDB using docker. So let’s get started.
Install MongoDB using the docker
For this demo, I will be using docker to install MongoDB. Follow this link to download docker.
Now let’s verify if the docker is running.
➜ docker --version Docker version 20.10.3, build 48d30b5
Awesome, now let’s proceed further and pull the mongo official image from dockerhub.
➜ docker pull mongo Using default tag: latest latest: Pulling from library/mongo 4bbfd2c87b75: Pull complete d2e110be24e1: Pull complete 889a7173dcfe: Pull complete 6f6a1a25f35a: Pull complete e87b34c16538: Pull complete 7099eef4dfe4: Pull complete 29b1d79d3b5b: Pull complete b5c178e98a5a: Pull complete ded800e62b93: Pull complete b09aa2e255f0: Pull complete c7e0f50ad27a: Pull complete dcdad63a2ffa: Pull complete Digest: sha256:482a562bf25f42f02ce589458f72866bbe9eded5b6f8fa5b1213313f0e00bba2 Status: Downloaded newer image for mongo:latest docker.io/library/mongo:latest
Verify if the docker image gets downloaded
➜ docker images REPOSITORY TAG IMAGE ID CREATED SIZE mongo latest 81a352f64d83 16 hours ago 449MB
Now let’s start the docker container
➜ docker run --name my-mongo -d mongo:latest 659e36f1f2b967c8cb20b1697181d03f43b83468af29c2091de40690601849ca
Type the below command to go inside the docker container
➜ docker exec -it my-mongo /bin/bash [email protected]:/#
Verify mongo version
[email protected]:/# mongo --version MongoDB shell version v4.4.6 Build Info: { "version": "4.4.6", "gitVersion": "72e66213c2c3eab37d9358d5e78ad7f5c1d0d0d7", "openSSLVersion": "OpenSSL 1.1.1 11 Sep 2018", "modules": [], "allocator": "tcmalloc", "environment": { "distmod": "ubuntu1804", "distarch": "x86_64", "target_arch": "x86_64" } } [email protected]:/#
Awesome, you have successfully installed MongoDB; let’s proceed further and see some of the commonly used MongoDB commands.
MongoDB commands
MongoDB has a vibrant command-line interface, using which we can easily interact with MongoDB.This tutorial will see some of the most widely used MongoDB commands.
Type the below command to get inside the mongo shell.
[email protected]:/# mongo MongoDB shell version v4.4.6 connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb ................<supressed o/p>............ ................<supressed o/p>............ --- >
List Databases
show dbs command will list all the databases present in MongoDB.By default, MongoDB has some system databases created.
> show dbs admin 0.000GB config 0.000GB local 0.000GB
Create new Database
use the <dbname> command will create a new database in MongoDB
> use naivetech switched to db naivetech
To view the current database
with the help of the db command; we can verify the current database user are in.
> db naivetech
Create a new collection
Now let’s create a test collection in the naivetech database
> db.createCollection('test')
{ "ok" : 1 }List collections in MongoDB
To list all the collections in the mongo naivetech database, type the below command:
> show collections test
Drop a collection
Let’s drop the test collection that we created earlier
> db.test.drop() true
Delete a database
To drop any database, switch to that database and type the below command to delete:
> db.dropDatabase()
{ "dropped" : "naivetech", "ok" : 1 }Insert a document in the MongoDB collection
Now let’s proceed further and create another database, naivetechblog, and a new collection of tech
> use naivetechblog
switched to db naivetechblog
> db.createCollection("tech")
{ "ok" : 1 }Type the below command to insert a document in the tech collection
> db.tech.insert({
... 'Kind': 'Mobile',
... 'lang': 'iphone 6s',
... 'Rating': 4.2
... })
WriteResult({ "nInserted" : 1 })
>Show documents in a MongoDB collection
Let’s list all the documents present in the tech collection
> db.tech.find()
{ "_id" : ObjectId("60c37656a9c3d411ad96c6e6"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }Pretty command
With MongoDB pretty command, we can print the output in a pretty format
> db.tech.find().pretty()
{
"_id" : ObjectId("60c37656a9c3d411ad96c6e6"),
"Kind" : "Mobile",
"lang" : "iphone 6s",
"Rating" : 4.2
}
>Insert many documents in the MongoDB collection
Sometimes we need to insert more than 1 document at one go in our MongoDB collection. With MongoDB insert many command, we can insert multiple documents.
> db.tech.insertMany([
... {
... 'Kind': 'Mobile',
... 'lang': 'iphone 6s',
... 'Rating': 4.2
... },
... {
... 'Kind': 'laptop',
... 'lang': 'acer',
... 'Rating': 3.9
... },
... {
... 'Kind': 'mobile',
... 'lang': 'samsung',
... 'Rating': 4.0
... },
... ])
{
"acknowledged" : true,
"insertedIds" : [
ObjectId("60c37883a9c3d411ad96c6e7"),
ObjectId("60c37883a9c3d411ad96c6e8"),
ObjectId("60c37883a9c3d411ad96c6e9")
]
}Now let’s verify if all documents get created.
> db.tech.find()
{ "_id" : ObjectId("60c37656a9c3d411ad96c6e6"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e7"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e8"), "Kind" : "laptop", "lang" : "acer", "Rating" : 3.9 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e9"), "Kind" : "mobile", "lang" : "samsung", "Rating" : 4 }
>Search MongoDB
With the help of the find command, we can filter out/search the documents. Let’s try to find the documents which contain mobile details.
> db.tech.find({Kind:'Mobile'})
{ "_id" : ObjectId("60c37656a9c3d411ad96c6e6"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e7"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
>FindOne command in MongoDB
findOne command displays the first output based on the filter criteria
db.tech.findOne({Kind:'Mobile'})
{
"_id" : ObjectId("60c37656a9c3d411ad96c6e6"),
"Kind" : "Mobile",
"lang" : "iphone 6s",
"Rating" : 4.2
}
>Limit command
With the limit command, we can limit the no of documents to be displayed in MongoDB
> db.tech.find().limit(2)
{ "_id" : ObjectId("60c37656a9c3d411ad96c6e6"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e7"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
>Count command
Count command Counts the number of rows in the query output. Let’s try to find all documents present in the MongoDB tech database.
> db.tech.find().count() 4
Insert document with different schema in MongoDB
In MongoDB, we can insert data with different schema; we don’t have to stick to any schema while inserting data in mongo collection.
Let’s insert a document in mongo with a different schema than we inserted earlier.
db.tech.insert({
'Kind': 'Mobile',
'lang': 'iphone 6s',
'Build_year': 2013 ,
'Rating': 4.2
})Let’s verify if the data gets inserted.
db.tech.find()
{ "_id" : ObjectId("60c37656a9c3d411ad96c6e6"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e7"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e8"), "Kind" : "laptop", "lang" : "acer", "Rating" : 3.9 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e9"), "Kind" : "mobile", "lang" : "samsung", "Rating" : 4 }
{ "_id" : ObjectId("60c38f5ca9c3d411ad96c6ea"), "Kind" : "Mobile", "lang" : "iphone 6s", "Build_year" : 2013, "Rating" : 4.2 }Update command in MongoDB
The update command modifies the existing document or documents in a collection. With the update command, we can modify specific fields of an existing document or replace an existing document.
This session will see some of the most widely used update commands.
Update a row
Let’s use an update command to update a document where Kind: laptop.
verify the data before updating
> db.tech.find({Kind:'laptop'})
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e8"), "Kind" : "laptop", "lang" : "acer", "Rating" : 3.9and run the update command
> db.tech.update({'Kind': 'laptop'},
... { 'Kind': 'laptop',
... 'Brand': 'samsung',
... 'Rating': 4.3
... })
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })Verify if the data gets successfully updated.
> db.tech.find({Kind:'laptop'})
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e8"), "Kind" : "laptop", "Brand" : "samsung", "Rating" : 4.3 }Update with upsert
upsert flag in the update command inserted a new document in MongoDB if the document does not exist.
> db.tech.update({'Kind': 'game'},
... { 'Kind': 'game',
... 'Brand': 'sony',
... 'Rating': 4.3
... }, {upsert: true})
WriteResult({
"nMatched" : 0,
"nUpserted" : 1,
"nModified" : 0,
"_id" : ObjectId("60c3984464d905a23322abb1")
})We got nUpserted”: 1 in the output, which means the record was not present in MongoDB, and the update command has added it as a new document.
Let’s verify the document.
> db.tech.find()
{ "_id" : ObjectId("60c37656a9c3d411ad96c6e6"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e7"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e8"), "Kind" : "laptop", "Brand" : "vivo", "Rating" : 4.3 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e9"), "Kind" : "mobile", "lang" : "samsung", "Rating" : 4 }
{ "_id" : ObjectId("60c38f5ca9c3d411ad96c6ea"), "Kind" : "Mobile", "lang" : "iphone 6s", "Build_year" : 2013, "Rating" : 4.2 }
{ "_id" : ObjectId("60c3984464d905a23322abb1"), "Kind" : "game", "Brand" : "sony", "Rating" : 4.3 }Inc command
With the inc command, we can update the documents filed by specific value. Let’s run this command and update the build_year by 2.
Document before updating
db.tech.find({Kind:'Mobile'})
{ "_id" : ObjectId("60c37656a9c3d411ad96c6e6"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e7"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c38f5ca9c3d411ad96c6ea"), "Kind" : "Mobile", "lang" : "iphone 6s", "Build_year" : 2013, "Rating" : 4.2 }Now, let’s update the document
> db.tech.update({'Build_year': 2013},
... {$inc:{
... Build_year: 2
... }})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
>Now let’s verify the data after the update
db.tech.find({Kind:'Mobile'})
{ "_id" : ObjectId("60c37656a9c3d411ad96c6e6"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e7"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c38f5ca9c3d411ad96c6ea"), "Kind" : "Mobile", "lang" : "iphone 6s", "Build_year" : 2015, "Rating" : 4.2 }Rename command
With rename command, we can update the document filed in the MongoDB collection
db.tech.update({'Build_year': 2015},
{$rename:{
lang: "brand"
}})verify the data after renamed
> db.tech.find({'Build_year': 2015})
{ "_id" : ObjectId("60c38f5ca9c3d411ad96c6ea"), "Kind" : "Mobile", "Build_year" : 2015, "Rating" : 4.2, "brand" : "iphone 6s" }The complete list of update commands can be found here
Delete command in MongoDB
We can delete any document from the mongo collection with the delete command. Let’s delete the Kind: game from the tech collection
Data before deletion
db.tech.find()
{ "_id" : ObjectId("60c37656a9c3d411ad96c6e6"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e7"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e8"), "Kind" : "laptop", "Brand" : "vivo", "Rating" : 4.3 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e9"), "Kind" : "mobile", "lang" : "samsung", "Rating" : 4 }
{ "_id" : ObjectId("60c38f5ca9c3d411ad96c6ea"), "Kind" : "Mobile", "Build_year" : 2015, "Rating" : 4.2, "brand" : "iphone 6s" }
{ "_id" : ObjectId("60c3984464d905a23322abb1"), "Kind" : "game", "Brand" : "sony", "Rating" : 4.3 }Delete the document
db.tech.remove({"Kind":"game"})
WriteResult({ "nRemoved" : 1 })Verify the data after the deletion
db.tech.find()
{ "_id" : ObjectId("60c37656a9c3d411ad96c6e6"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e7"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e8"), "Kind" : "laptop", "Brand" : "vivo", "Rating" : 4.3 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e9"), "Kind" : "mobile", "lang" : "samsung", "Rating" : 4 }
{ "_id" : ObjectId("60c38f5ca9c3d411ad96c6ea"), "Kind" : "Mobile", "Build_year" : 2015, "Rating" : 4.2, "brand" : "iphone 6s" }Less than command in mongoDB
In MongoDB, we can use less than one command to filter out the document based on filter criteria. Let’s filter out the Mobile whose rating is less than 4.2
db.tech.find({Rating: {$lt: 4.2}})
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e9"), "Kind" : "mobile", "lang" : "samsung", "Rating" : 4 }Less than equal to command in MongoDB
Like less than command, we can use less than equal command in MongoDB to filter out documents.
db.tech.find({Rating: {$lte: 4.2}})
{ "_id" : ObjectId("60c37656a9c3d411ad96c6e6"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e7"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e9"), "Kind" : "mobile", "lang" : "samsung", "Rating" : 4 }
{ "_id" : ObjectId("60c38f5ca9c3d411ad96c6ea"), "Kind" : "Mobile", "Build_year" : 2015, "Rating" : 4.2, "brand" : "iphone 6s" }Greater than command
Let’s filter out the Mobile whose rating is greater than 4.2
db.tech.find({Rating: {$gt: 4.2}})
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e8"), "Kind" : "laptop", "Brand" : "vivo", "Rating" : 4.3 }Greater than equal to command
Similar to the greater than command, we can use the greater than equal command in MongoDB to filter out documents.
db.tech.find({Rating: {$gte: 4.2}})
{ "_id" : ObjectId("60c37656a9c3d411ad96c6e6"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e7"), "Kind" : "Mobile", "lang" : "iphone 6s", "Rating" : 4.2 }
{ "_id" : ObjectId("60c37883a9c3d411ad96c6e8"), "Kind" : "laptop", "Brand" : "vivo", "Rating" : 4.3 }
{ "_id" : ObjectId("60c38f5ca9c3d411ad96c6ea"), "Kind" : "Mobile", "Build_year" : 2015, "Rating" : 4.2, "brand" : "iphone 6s" }Conclusion
I hope you have liked this tutorial. Please do let me know in the comment box. I will be more than happy to hear from you.
