All about MongoDB command 📝

SQL to MongoDB Mapping Chart

This document provides a mapping of common SQL terminology and concepts to their MongoDB equivalents

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📘 Terminology and Concepts

The following table maps SQL terms to their MongoDB counterparts:

SQL Terms/Concepts	MongoDB Terms/Concepts
database	database
table	collection
row	document or BSON document
column	field
index	index
table joins	$lookup, embedded documents
primary key	Specify any unique column or column combination
primary key (MongoDB)	_id field is the default primary key
aggregation (e.g. GROUP BY)	aggregation pipeline
SELECT INTO NEW_TABLE	$out (see Aggregation Mapping Chart)
MERGE INTO TABLE	$merge (see Aggregation Mapping Chart)
UNION ALL	$unionWith
transactions	transactions

💡 For many scenarios, MongoDB's denormalized data model (using embedded documents and arrays) is optimal. This often reduces the need for multi-document transactions.

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Installation

With Docker

Pull the MongoDB Docker Image

docker pull mongodb/mongodb-community-server:latest

Run the Image as a Container

docker run --name mongodb -p 27017:27017 -d mongodb/mongodb-community-server:latest

Go to container and Connect to the MongoDB Deployment with mongosh

mongosh --port 27017

for more detail click here

Databases Crud Commands 🚀

List Databases

below commands use to list all databses in mongoDB

show dbs;

or

show databases;

To select current DB/Create Database

Below command is used to creating a database. This command will tell the MongoDB client to create a database by this name if there is no database exists by this name. Otherwise, this command will return the existing database.

use <db_name>;

Update Databases

db.copyDatabase("oldDBName", "newDBName")

Delete Databases

current selected databases will be deleted

db.dropDatabase()

Dump data to files(Export database)

mongodump --out c:\backupDatabase

Load load data from files(Import database)

mongorestore --db databaseName --collection <collectionName>   <directory\collectionName.bson>

Collections(Table) CRUD Commands 🚀

List All Collections

show collections;

or

show tables;

or

db.getCollectionNames();

Create Collections

 db.createCollection("<Collection_name>");

Update Collections(Rename)

 db.<collection_name>.renameCollection("<new_collection_name>")

Delete Collections

db.<collection_name>.drop()

Documents(Rows) CRUD Commands

Insert Documents

Insert single Documents

db.<collection_name>.insertOne(
  {
    title: "The Favourite",
    genres: [ "Drama", "History" ],
    runtime: 121,
    rated: "R",
    year: 2018,
    directors: [ "Yorgos Lanthimos" ],
    cast: [ "Olivia Colman", "Emma Stone", "Rachel Weisz" ],
    type: "movie"
  }
)

Insert multiple Documents

db.<collection_name>.insertMany([
   { title: "Jurassic World: Fallen Kingdom", genres: [ "Action", "Sci-Fi" ], runtime: 130, rated: "PG-13", year: 2018, directors: [ "J. A. Bayona" ]},
   { title: "Tag",                            genres: [ "Comedy", "Action" ], runtime: 105, rated: "R",     year: 2018, directors: [ "Jeff Tomsic" ]}
])

Fetch Documents(rows)

To fetch all data from collection

db.<collection_name>.find({})

To fetch all document where key(column name )=value

db.<collection_name>.find( { "title": "Titanic" } )

$In Operator is used to fetch all document where key in []

db.<collection_name>.find( { rated: { $in: [ "PG", "PG-13" ] } } )

meaning: select * from collection_name where rated in ("PG", "PG-13")

Specify Logical Operators (AND)

AND

db.movies.find( { countries: "Mexico", "imdb.rating": { $gte: 7 } } )

meaning SELECT * FROM movies WHERE countries = 'Mexico' AND imdb_rating >= 7;

$OR Operator

db.movies.find( {
     year: 2010,
     $or: [ { "awards.wins": { $gte: 5 } }, { genres: "Drama" } ]
} )

meaning SELECT m.* FROM movies m LEFT JOIN movie_genres mg ON m.id = mg.movie_id WHERE m.year = 2010 AND ( m.awards_wins >= 5 OR mg.genre = 'Drama');

Update Documents

To update single document updateOne method

db.movies.updateOne({title:{"$regex":"the$"}},{ $set: {"awards.win":12}, $currentDate : {lastupdated:true}})

meaning UPDATE movies SET awards_win = 12, lastupdated = CURRENT_TIMESTAMP WHERE id = ( SELECT id FROM movies WHERE title ~* 'the$' LIMIT 1 );

To update multiple Documents updateMany method

db.movies.updateMany({title:{"$regex":"the$"}},{ $set: {"awards.win":12,year:2015}, $currentDate : {lastupdated:true}})

meaning UPDATE movies SET awards_win = 12, year = 2015, lastupdated = CURRENT_TIMESTAMP WHERE title ~* 'the$';

To replace the entire content of a document except for the _id field, pass an entirely new document as the second argument to db.collection.replaceOne()

db.<collection_name>.replaceOne(
  { account_id: 371138 },
  { account_id: 893421, limit: 5000, products: [ "Investment", "Brokerage" ] }
)

meaning : above command will find one document which have account_id=371138 and set new document Specify as second argument

Delete Documents

To delete one document use deleteOne method

 db.movies.deleteOne({title: 'Breathe'})

To delete multiple document use deleteMany method

 db.movies.deleteMany({"imdb.rating":{$gt:1, $lt: 4}})

Sorting Documents

desceding order

 db.<collection_name>.find().sort({<key_name>>:-1})

asceding order

 db.<collection_name>.find().sort({<key_name>>:1})

limit and Skip

using limit keyword we can specify number of document for output.

 db.movies.find().limit(1)

using skip keyword we can skip first given number of document for output. query will skip given number of document and return documents after skipped document

 db.movies.find().skip(1)

MongoDB Query and Projection Operators

This guide provides a detailed overview of MongoDB Query Selectors, Logical Operators, Evaluation, Geospatial Queries, Array Queries, Bitwise Operations, Projection Operators, and Miscellaneous Operators.

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📗 Query Selectors

Comparison Operators

Name	Description
$eq	Matches values that are equal to a specified value.
$gt	Matches values that are greater than a specified value.
$gte	Matches values that are greater than or equal to a specified value.
$in	Matches any of the values specified in an array.
$lt	Matches values that are less than a specified value.
$lte	Matches values that are less than or equal to a specified value.
$ne	Matches all values that are not equal to a specified value.
$nin	Matches none of the values specified in an array.

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📘 Logical Operators

Name	Description
$and	Joins query clauses with a logical AND; returns documents matching all conditions.
$not	Inverts the effect of a query predicate; returns documents that do not match the predicate.
$nor	Joins query clauses with a logical NOR; returns documents that fail to match both clauses.
$or	Joins query clauses with a logical OR; returns documents matching either clause.

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📙 Element Operators

Name	Description
$exists	Matches documents that contain the specified field.
$type	Selects documents if a field is of the specified BSON type.

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📒 Evaluation Operators

Name	Description
$expr	Allows the use of aggregation expressions within the query language.
$jsonSchema	Validates documents against the given JSON Schema.
$mod	Performs a modulo operation on the value of a field and selects documents with the specified result.
$regex	Selects documents where values match a specified regular expression.
$text	Performs text search. (For Atlas, use Atlas Search for improved capabilities.)
$where	Matches documents that satisfy a JavaScript expression.

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🗺️ Geospatial Operators

Name	Description
$geoIntersects	Selects geometries that intersect with a GeoJSON geometry (supports 2dsphere index).
$geoWithin	Selects geometries within a bounding GeoJSON geometry (supports 2dsphere and 2d indexes).
$near	Returns geospatial objects near a point (requires a geospatial index).
$nearSphere	Returns geospatial objects near a point on a sphere (requires a geospatial index).

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📚 Array Operators

Name	Description
$all	Matches arrays that contain all elements specified in the query.
$elemMatch	Selects documents if an element in the array field matches all specified conditions.
$size	Selects documents if the array field is a specified size.

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🧠 Bitwise Operators

Name	Description
$bitsAllClear	Matches values where all specified bit positions are clear (0).
$bitsAllSet	Matches values where all specified bit positions are set (1).
$bitsAnyClear	Matches values where any specified bit position is clear (0).
$bitsAnySet	Matches values where any specified bit position is set (1).

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🖼️ Projection Operators

Name	Description
$	Projects the first array element that matches the query condition.
$elemMatch	Projects the first array element that matches the specified $elemMatch condition.
$meta	Projects the document's score assigned during the $text operation.
$slice	Limits the number of elements projected from an array (supports skip and limit).

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🔀 Miscellaneous Operators

Name	Description
$rand	Generates a random float between 0 and 1.
$natural	A special hint to force forward or reverse collection scan (sort() or hint() methods).

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