Saha-Kamalika / MongoDB

This repository provides a comprehensive guide to MongoDB, an open-source, document-oriented NoSQL database. It includes MongoShell commands ranging from basic to advanced levels and showcases projects integrating Node.js and MongoDB.

MongoShell Commands

USING COLLECTION

• use collection_name

CREATING COLLECTION

• db.createCollection('collection_name')

DROP COLLECTION

• db.collection_name.drop()

DROP DATABASE

• db.dropDatabase()

INSERTING SINGLE DATA IN DOCUMENT

• db.document_name.insertOne({object})

INSERTING MULTIPLE DATA IN DOCUMENT

• db.document_name.insertMany([{object1}, {object2}])

📍📍 ORDERED & UNORDERED INSERTS: determines the batch behaviour

• By default : ordered (MongoDB stops after encountering an error)
  
• unordered (continues to perform the write operations): db.col_name([],{ordered: false})

CURSOR METHODS

• count()
• limit()
• skip()
• sort()

ELEMENT OPERATORS

• $exists
• $type

IMPORTING AND EXPORTING JSON FILES

• in root directory: mongoimport json_file_path -d db_name -c collection_name
• in root directory: mongoexport -d db_name -c collection_name -o json_file_path

USING EXPRESSIONS IN COMMANDS

• db.col_name.find({$expr: {$gt: [{$multiply: ['$field1','$field2']},'field3']}})

FILTERING DOCUMENTS

• db.document_name.find({property_name: value})

SORTING DOCUMENTS

• db.document_name.sort({property_name: 1}) //sorts in ascending order
  
• db.document_name.sort({property_name: -1}) //sorts in descending order

OPERATORS & COMPLEX QUERIES

• Using $gte, $lte, $or: db.shop.find({$or: [{price: {$lte: 100}}, {price: {$gte: 100}}]})
• Using $in, $nin: db.shop.find({product: {$in: ["notebook","crayons"]})

UPDATING DOCUMENTS

• using $set: db.doc_name.updateOne({_id: object_id}, {$set: {key: value}})
• using $inc: db.doc_name.updateOne({_id: object_id}, {$inc: {key: increment_val}})
• using $pull & $push: db.doc_name.updateOne({_id: object_id}, {$pull: {key: value}}) //operates ony on arrays

REMOVING AND RENAMING FIELDS IN DOCUMENTS

• db.col_name.updateOne({filter}, {$unset: {fieldName: 1}})
• db.col_name.updateOne({filter}, {$rename: {oldFieldName: newFieldName}})

DELETING DOCUMENTS

• db.col_name.deleteOne({filter})
• db.col_name.deleteMany({filter})

INDEXES

• db.col_name.createIndex({fieldName: 1})
• db.col_name.getIndexes()
• db.col_name.dropIndex({fieldName: 1})

AGGREGATION

• db.col_name.aggregate({$match: {query}})
• db.col_name.aggregate([{$group: {_id: '$fieldName'}, varname: {$sum: 1}}])
• db.col_name.aggregate([{$project: {fieldName: 1, 'varName': {$filter: {input: '$fieldName', as: 'alias', cond: {$gt: ['$$alias', value]}}}}}}])