Now every document within this query will have the field name “date_of_birth” in place of “dob”.Select “Documents matching query criteria” from the dropdown box.Type in the new field name (“date_of_birth”) and hit “Enter”.Find the field that you would like to rename (“dob”) and right click it.Open one of the documents resulting from the query search.The _id field is immutable, however you can add a new document with an _id field of any BSON data type other than array.Īn example of a custom ID (in this example, string) – and hit “Enter”. If the user doesn’t specify an _id field when creating a new document, MongoDB automatically creates ObjectId value represented as a string of numbers. The most important thing to remember is that each MongoDB document requires a unique _id field, which serves as the primary locator key for each document. The full list of types can be found here. ![]() A group of documents together is known as a collection.įields in a MongoDB document can be of any BSON data type. ![]() It’s comprised of field/value pairs which are written in BSON format.Ī field is the name/value pair in a MongoDB document while a value is the specific value of a document’s field/value pair. A document is the basic unit of data in MongoDB. "Delete Documents." Documentation, MongoDB 5.0. "Insert Methods." Documentation, MongoDB 5.0. "Insert Documents." Documentation, MongoDB 5.0. "MongoDB CRUD Operations." Documentation, MongoDB 5.0. "mongosh Methods." Documentation, MongoDB. "Write Scripts for the mongo Shell." Documentation, MongoDB 5.0. "Release Notes for MongoDB 3.6." November. "Release Notes for MongoDB 3.4." November 29. "Release Notes for MongoDB 3.2." December 8. "Release Notes for MongoDB 3.0." March 3. "1.0 GA Released." Blog, MongoDB, August 27. "History Of MongoDB Aggregations." Section 1.2 in: Practical MongoDB Aggregations, v3.00, MongoDB, Inc. "MongoDB Cheat Sheet." MongoDB, September 30. "48 MongoDB Commands and Queries to Know as Developer and DBA." Geekflare, July 4. It provides better support for field names that are $ prefixed or include. What are the update operators in MongoDB?.db.people.find().skip(3).limit(5): Skip first three documents and show only the next five.db.people.find(): Sort by price and then reverse sort by quantity.db.people.find(): Retrieve all fields of all documents.Here are some sample commands on a collection named people: Method findOne(query, projection) returns the first matching document, not a cursor. The method returns a cursor to the documents. Projection parameter specifies what fields to retrieve. The main method is find(query, projection). How do I find documents in a MongoDB collection?.Some methods that do this are update(), updateOne(), updateMany(), findAndModify(), findOneAndUpdate(), findOneAndReplace(), and bulkWrite(). It's also possible to insert new documents with the option upsert: true. Methods include deleteOne() (first matching document is deleted) and deleteMany(), called with query criteria. Delete: Remove documents from a collection.Method calls include query criteria and what to update. Methods include updateOne(), updateMany() and replaceOne(). Update: Modify existing documents of a collection.Main method is find(), called with query criteria (how to match documents) and projection (what fields to retrieve). Read: Retrieve documents from a collection.Unique _id field is automatically added to each document if not specified in the method calls. If the collection doesn't exist, it will be created. Methods include insertOne() and insertMany(). Create: Add documents to a collection. ![]() MongoDB supports CRUD with the following methods of Collection class: Source: Adapted from MongoDB Docs 2021c.ĭatabase operations are conveniently referred to as CRUD (Create, Read, Update, Delete).
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