MongoDB Cheat Sheet "issr Master"

A Programming › MongoDB cheat sheet in English by hanysamir

MongoDB cheat sheet customized for Cairo University, Faculty of Graduate Studies for Statistical Research "Master"

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PRs

Commmand	Description	Example
mongod	start the mongo service	mongod --dbpath /home/mongo --logpath /home/mongo/mongod.log --bind_ip 0.0.0.0
mongosh	command run mongodb shell	mongosh
show dbs	list databases	show dbs
use db_name	Switch to database db	use company
db	show current database name	db
show collections	List current database collections	show collections

syntax	Description	Example
insertOne (data, options)	insert one document	db.people.insertOne({ "ssn":1, "name":"Ali","age":20})
insertMany([{document1},{document2}])	insert many documents, square brackets are mandatory	"db.sales.insertMany([ { ""item"": ""abc"", ""price"": 10}, { ""item"": ""xyz"", ""price"": 5 } ])"

syntax	Description	Example
deleteOne(filter, options)	delete the first matching document from collection	db.project.deleteOne( { "pnumber": 1 } )
deleteMany(filter, options)	delete all matching documents from the project collection	db.project.deleteMany( { "plocation": "Stafford" } )

syntax	Description	Example
updateOne(filter, data, options)	update one document	db.sales.updateOne({"item":"abc"}, { "$set" : {"price": 22} } )
updateMany(filter, data, options)	update matching documents.	db.sales.updateMany ( { ""_id"":{""$gte"":14, ""$lte"":16} } , { $unset : { ""price"" : "" ""} } )

$set to update the field value
$unset will remove the field

syntax	Description	Example
createIndex( {keys} , {options} )	Creates indexes on collections.	db.project.createIndex( { "pnumber": 1, "Pname": -1 } , { "name": "pno_name" , "unique": true} )
dropIndex(index)	Delete index	db.project.dropIndex("pno_name")
getIndexes()	List indexes on collection.	db.project.getIndexes()

if index name was not specified withing options, the name will be generated automatically.
1 = ascending order
-1 = descending order

syntax	Description	Example
findOne(filter, options)	find first matching document	db.employee.findOne({"dno": 8},{"_id":0,"fname":1,"lname":1})
find(filter, options)	find all matching documents	db.employee.find({"dno": 8},{"_id":0,"fname":1,"lname":1})

syntax	Description	Example
sort({field_name:1 or -1})	find first matching document	db.sales.find().sort({"price": 1})
limit(n)	Limits the number of documents	db.sales.find().limit(3)
skip(n)	Skips over the specified number of documents	db.sales.find().skip(3)

1 = ascending order
-1 = descending order

syntax	Description	Example
$group	The $group stage separates documents into groups according to a "group key". The output is one document for each unique group key.	db.employee.aggregate([ { "$group" : { "_id" : null, "averageSalary": { "$avg": "$salary" } } } ])
Accumulator Operator
	$avg	Returns an average of numerical values.
	$max	Returns the highest expression value for each group.
	$min	Returns the lowest expression value for each group.
	$sum	Returns a sum of numerical values. Ignores non-numeric values.
$lookup	Performs a left outer join to a collection in the same database to filter in documents from the "joined" collection for processing. The $lookup stage adds a new array field to each input document. The new array field contains the matching documents from the "joined" collection. The $lookup stage passes these reshaped documents to the next stage.	db.orders.aggregate( [ { $lookup: { from: "inventory", localField: "item", foreignField: "sku", as: "inventory_docs" } } ] )
The $lookup takes a document with these fields:
	from	Specifies the collection in the same database to perform the join with.
	localField	Specifies the field from the documents input to the $lookup stage.
	foreignField	Specifies the field from the documents in the from collection.
	as	Specifies the name of the new array field to add to the input documents.

$and:[array]	AND operation between all array of expressions
$or:[array]	OR operation between all array of expressions
$nor:[array]	All array expressions must fail.
$not:Expr	Performs a logical NOT operation on the specified <operator-expression>

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

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