mongoDB

mongoDB Tutorial

MongoDB works on concept of collection and document.

Database

• Database is a physical container for collections
• Every database has its own set of files on the system.

Collection

• Collection is a group of MongoDB documents.

Document

• A document is a set of key-value pairs.

Database Commands of mongoDB

• The use Command
• Used to create database
• The command will create a new database if it doesn't exist, otherwise it will return the existing database
• use DATABASE_NAME
• db Command
• Used To check your currently selected database
• db
• show dbs Command
• Used  to check your databases list
• show dbs
• The dropDatabase() Command
• This will delete the selected database
• dropDatabase()
• If you have not selected any database, then it will delete full database
• To drop a collection from the database
• db.collection.drop()
• The createCollection() Command
• Used to create collection.
• db.createCollection(name, options)
• Name - String
• Option - Document
• The insert() Command
• Used to insert data into MongoDB collection
• db.Collection_name.insert()
• The find() Command
• Used to find data from MongoDB collection
• db.Collection_name.find()
• It will display all the documents in a non-structured way
• To display the results in a formatted way, you can use method.pretty()
•  db.Collection_name.find().pretty()
• To find something specific
• db.mycol.find({},{"title":1,_id:0}) 
• Less Than, Grater Than Commands

• And Operation

• Or Operation



• And & Or Operation




• The update() Command
• Used to update the values in the existing document
• db.CollectionName.update(SELECTION_CRITERIA, UPDATED_DATA)
• By default, MongoDB will update only a single document. To update multiple documents, you need to set a parameter 'multi' to true
• db.mycol.update({'title':'MongoDB Overview'}, {$set:{'title':'New MongoDB Tutorial'}},{multi:true})
• The save() Command
• It replaces the existing document with the new document passed in the save() method
• db.Collectionname.save({_id:ObjectId(),NEW_DATA})
• The remove() Command
• Used to remove a document from the collection.
• db.CollectionName.remove(DELLETION_CRITTERIA)
• If there are multiple records and you want to delete only the first record, then set justone parameter in remove() method.
• The aggregate() Command
• Aggregations operations process data records and return computed results
• Aggregation operations group values from multiple documents together, and can perform a variety of operations on the grouped data to return a single result
• For the aggregation in MongoDB, you should use method aggregate()
• Eg s for Aggregate Functions
• $sum
• $ave
• $min
• $max
• $sort
• $skip
• $group
• For More Inoformation -   MongoDB - Aggregation

To Know About MongoDB Commands, Visit www.tutorialspoint.com/mongodb