mongoDB
MongoDB (from humongous) is a free and open-source cross-platform document-oriented database program. Classified as a NoSQL database program, MongoDB uses JSON-like documents with schemas.
(01)what is mongo db?
MongoDB is a cross-platform, document oriented database that provides, high performance, high availability, and easy scalability.
MongoDB works on concept of collection and document.
(02)Why Use MongoDB?
- Document Oriented Storage: Data is stored in the form of JSON style documents.
- Index on any attribute
- Replication and high availability
- Auto-sharding
- Rich queries
- Fast in-place updates
- Professional support by MongoDB
The use Command
MongoDB use DATABASE_NAME is used to create database. The command will create a new database if it doesn't exist, otherwise it will return the existing database.Syntax
Basic syntax of use DATABASE statement is as follows −
use DATABASE_NAME()
The dropDatabase() Method
MongoDB db.dropDatabase() command is used to drop a existing database.
Syntax
Basic syntax of dropDatabase() command is as follows −
use DATABASE_NAME()
db.dropDatabase()
The createCollection() Method
MongoDB db.createCollection(name, options) is used to create collection.
Syntax
Basic syntax of createCollection() command is as follows −
db.createCollection(name, options)
The drop() Method
MongoDB's db.collection.drop() is used to drop a collection from the database.
Syntax
Basic syntax of drop() command is as follows −
db.COLLECTION_NAME.drop()
The insert() Method
To insert data into MongoDB collection, you need to use MongoDB's insert() or save() method.
Syntax
The basic syntax of insert() command is as follows −
>db.COLLECTION_NAME.insert(document)
update document in mongo db..
MongoDB's update() and save() methods are used to update document into a collection. The update() method updates the values in the existing document while the save() method replaces the existing document with the document passed in save() method.
MongoDB Update() Method
The update() method updates the values in the existing document.
Syntax
The basic syntax of update() method is as follows −
>db.COLLECTION_NAME.update(SELECTION_CRITERIA, UPDATED_DATA)
The remove() Method
MongoDB's remove() method is used to remove a document from the collection. remove() method accepts two parameters. One is deletion criteria and second is justOne flag.
deletion criteria − (Optional) deletion criteria according to documents will be removed.
justOne − (Optional) if set to true or 1, then remove only one document.
Syntax
Basic syntax of remove() method is as follows −
>db.COLLECTION_NAME.remove(DELLETION_CRITTERIA)
Remove Only One
If there are multiple records and you want to delete only the first record, then set justOne parameter in remove() method.
Syntax
>db.COLLECTION_NAME.remove(DELETION_CRITERIA,1)
The Limit() Method
To limit the records in MongoDB, you need to use limit() method. The method accepts one number type argument, which is the number of documents that you want to be displayed.
Syntax
The basic syntax of limit() method is as follows −
>db.COLLECTION_NAME.find().limit(NUMBER)
MongoDB Skip() Method
Apart from limit() method, there is one more method skip() which also accepts number type argument and is used to skip the number of documents.
Syntax
The basic syntax of skip() method is as follows −
>db.COLLECTION_NAME.find().limit(NUMBER).skip(NUMBER)
The sort() Method
To sort documents in MongoDB, you need to use sort() method. The method accepts a document containing a list of fields along with their sorting order. To specify sorting order 1 and -1 are used. 1 is used for ascending order while -1 is used for descending order.
Syntax
The basic syntax of sort() method is as follows −
>db.COLLECTION_NAME.find().sort({KEY:1})
The aggregate() Method
For the aggregation in MongoDB, you should use aggregate() method.
Syntax
Basic syntax of aggregate() method is as follows −
>db.COLLECTION_NAME.aggregate(AGGREGATE_OPERATION)
Basic syntax of remove() method is as follows −
>db.COLLECTION_NAME.remove(DELLETION_CRITTERIA)
Remove Only One
If there are multiple records and you want to delete only the first record, then set justOne parameter in remove() method.
Syntax
>db.COLLECTION_NAME.remove(DELETION_CRITERIA,1)
The Limit() Method
To limit the records in MongoDB, you need to use limit() method. The method accepts one number type argument, which is the number of documents that you want to be displayed.
Syntax
The basic syntax of limit() method is as follows −
>db.COLLECTION_NAME.find().limit(NUMBER)
MongoDB Skip() Method
Apart from limit() method, there is one more method skip() which also accepts number type argument and is used to skip the number of documents.
Syntax
The basic syntax of skip() method is as follows −
>db.COLLECTION_NAME.find().limit(NUMBER).skip(NUMBER)
The sort() Method
To sort documents in MongoDB, you need to use sort() method. The method accepts a document containing a list of fields along with their sorting order. To specify sorting order 1 and -1 are used. 1 is used for ascending order while -1 is used for descending order.
Syntax
The basic syntax of sort() method is as follows −
>db.COLLECTION_NAME.find().sort({KEY:1})
The aggregate() Method
For the aggregation in MongoDB, you should use aggregate() method.
Syntax
Basic syntax of aggregate() method is as follows −
>db.COLLECTION_NAME.aggregate(AGGREGATE_OPERATION)
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