MongoDB Cheatsheet

COMMANDS	THEIR USES
show dbs	To show the databases
use database-name	To create a new database
db.dropDatabase()	To delete the database
show collections	To show the collections in the database
db.createCollection('collection-name’)	To create a new collection in a database
db.collection-name.drop()	To delete a collection in a database
db.collection-name.insertOne({ field1:value1,field2: value2,...});	To insert data in a collection
db.collection-name.insertMany([{ field1: value1, field2: value2, ... },{ field1: value1, field2: value2, ... }])	To insert many data of objects in to a collection
db.collection-name.insertMany([ doc1, doc2, ... ]);	This command inserts multiple documents into a specified collection. By default, the ordered option is true i.e. Data before error will be added rest would not be added
db.collection-name.insertMany([ doc1, doc2, ... ], { ordered: false });	inserts multiple documents into a specified collection but with the ordered option set to false i.e. Data will be added except the error data
db.collection_name.find({ key: value })	To find all documents in a collection that match the specified condition
db.collection_name.findOne({ key: value })	To find a single document in a collection that matches the specified condition
mongoimport Yourjsonfile.json –d database_name –c collection_name	To import data in your specified collection & database in MongoDb
mongoimport Yourfile.json -d <Database-name> -c collection_name --jsonArray	To import data in your specified collection & database in MongoDb as Array document
mongoexport -d database -c collection-name -o <your-directory- where- you-want-to-save-file>	To export the data from mongo DB to your local machine
db.collection-name.find({ ‘fieldname’ : {$Operator : value}}) comparison operators - $eq , $ne, $gt, $gte, $lt, $lte, $in , $nin	To find any field using comparison operators
db.collection-name.find({ ‘fieldname’ : {$Operator : value}}).count();	To find quantity of that field using cursor Method
db.collection-name.find({ ‘fieldname’ : {$Operator : value}}).limit();	To find specified no. of data of that field using cursor Method
db.collection-name.find({ ‘fieldname’ : {$Operator : value}}).limit().skip();	To find specified no. of data while skipping some content of that field using cursor Method
db.collection-name.find({ ‘fieldname’ : {$Operator : value}}).sort();	To sort out field using cursor Method
{$and : [{condition 1}, {condition 2}] } logical operators - $and , $or , $not , $nor	To find the data with an condition logical operator
{ $expr: { operator: [field, value] } }	To perform query operations using aggregation expressions.
{ field: { $exists: <boolean>} }	This checks for the existence of a field. If is true, it matches documents that contain the field. If false, it matches documents that do not contain the field.
{ field: { $type: "bson-data-type" }}	This matches documents where the field is of the specified BSON data type.
{ field: { $size: array-length } }	This matches documents where the field is an array with the specified length.
db.collection.find({},{field1 :1 , field2 : 1})	This retrieves documents from the specified collection and projects only field1 and field2 (1 means include the field, 0 means exclude the field).
db.collection.find({"Parent.child" : value})	This queries for documents where the nested field child under Parent is equal to value.
{ field: { $all: [ value1 , value2 ... ] } }	This matches documents where the array field contains all the specified values.
{ field: { $elemMatch: { query1, query2, ... } } }	This matches documents where at least one element in the array field matches all the specified queries.
db.collectionName.updateOne({filter},{$set : {existingField : newValue},{newField : newValue}})	Updates a single document in the collection that matches the filter criteria. Sets the value of existingField to newValue and adds a new field newField with newValue.
db.collectionName.updateMany({filter},{$set : {existingField : newValue} })	Updates multiple documents that match the filter criteria. Sets the value of existingField to newValue in all matching documents.
db.collectionName.updateOne({filter},{ $unset: { fieldName: 1 } });	Updates a single document by removing fieldName.
db.collectionName.updateOne( {filter}, { $rename: { OldfieldName: "NewfieldName" } });	Updates a single document by renaming OldfieldName to NewfieldName.
db.collectionName.updateOne({ filter },{ $push: { arrayField: "new element" } });	Updates a single document by adding a new element to the array arrayField.
db.collectionName.updateOne({ filter },{ $pop: { arrayField: value } });	Updates a single document by removing the first (value: -1) or last (value: 1) element of the array arrayField.
db.collectionName.updateOne({ filter },{ set: { "arrayField.$.text": "Updated text" } });	Updates a single element within an array arrayField that matches the filter criteria. Sets text to "Updated text" for the matched array element.
db.collectionName.deleteOne({ filter });	Deletes a single document that matches the filter criteria.
db.collectionName.deleteMany({ filter });	Deletes all documents that match the filter criteria.
db.collectionName.find({ condition }).explain();	Returns information on the query plan and execution statistics for the find operation, with a default verbosity of "queryPlanner"
db.collectionName.find({ condition }).explain("executionStats");	Returns detailed execution statistics for the find operation, including the query plan.
db.collection.createIndex({ field: 1 });	Creates an ascending index on field in the collection.
db.collection.getIndexes();	Returns a list of all indexes on the collection.
db.collection.dropIndex({ field: 1 });	Drops the index on field in the collection.
db.collection.dropIndex(“index_name”);	Drops the index with the specified name.
db.collection.createIndex({ field: 1 }, { unique: true });	Creates a unique index on field, ensuring all values in the field are unique.
db.collection.createIndex({ field: "text" });	Creates a text index on the field to support text search operations.
db.collection.find({ $text: { $search: "keyword" } });	Searches for documents that contain the specified keyword using a text index.
db.collectionName.aggregate([ {$match : {<query>}}]);	Filters documents in the aggregation pipeline to only those that match the query criteria.
db.collectionName.aggregate([{ $group: { _id: { expression }, field1: { accumulator1 : expression1 }}} ]);	Groups documents by a specified _id expression and applies accumulator operations (like sum, avg, etc.) on the grouped documents.
db.collectionName.aggregate([{ $sort: { field: order } }]);	Sorts documents in the aggregation pipeline by field in the specified order (1 for ascending, -1 for descending).
db.collectionName.aggregate([{ $project: { field: expression1 , ... } } ]);	Reshapes documents in the aggregation pipeline by including, excluding, or adding new fields.
db.collectionName.aggregate([{ $push: { expression } } ]);	Adds an expression to an array field in the aggregation pipeline. Typically used within $group.
db.collectionName.aggregate([{ $unwind: array } ]);	Deconstructs an array field from the input documents to output a document for each element.
db.collectionName.aggregate([{ $addToSet: { field1: value1, ... } } ]);	Adds a value to an array only if it does not already exist in the array. Used within $group.
db.collectionName.aggregate([ { $size: array }]);	Returns the number of elements in an array.
db.collectionName.aggregate([ { $skip: positive value }, { $limit: positive value } ]);	Skips a specified number of documents and limits the number of documents passed to the next stage in the pipeline.
db.collectionName.aggregate([{$filter:{ input: array, as: string, cond: expression,limit: number expression }}]);	Filters an array to return only elements that match the specified condition (cond). Optionally limits the number of matching elements.

Note - for $in operator write value in array form in the command