MonogDB Cheatsheet MonogDB Cheatsheet, Cheat Sheet of Computer Science

Download MonogDB Cheatsheet MonogDB Cheatsheet and more Cheat Sheet Computer Science in PDF only on Docsity! MongoDB Cheat Sheet By Web Dev Simplified https://courses.webdevsimplified.com Terminology Database A container for collections. This is the same as a database in SQL and usually each project will have its own database full of different collections. Collection A grouping of documents inside of a database. This is the same as a table in SQL and usually each type of data (users, posts, products) will have its own collection. Document A record inside of a collection. This is the same as a row in SQL and usually there will be one document per object in the collection. A document is also essentially just a JSON object. Field A key value pair within a document. This is the same as a column in SQL. Each document will have some number of fields that contain information such as name, address, hobbies, etc. An important difference between SQL and MongoDB is that a field can contain values such as JSON objects, and arrays instead of just strings, number, booleans, etc. Basic Commands mongosh Open a connection to your local MongoDB instance. All other commands will be run within this mongosh connection. show dbs Show all databases in the current MongoDB instance use <dbname> use myDatabase Switch to the database provided by dbname Switch to myDatabase db Show current database name cls Clear the terminal screen show collections Show all collections in the current database db.dropDatabase() Delete the current database exit Exit the mongosh session Create Each of these commands is run on a specific collection db.<collectionName>.<command> insertOne db.users.insertOne({ name: “Kyle” }) Create a new document inside the specified collection Add a new document with the name of Kyle into the users collection insertMany db.users.insertMany([{ age: 26 }, { age: 20 }]) Create multi new documents inside a specific collection Add two new documents with the age of 26 and 20 into the users collection Read Each of these commands is run on a specific collection db.<collectionName>.<command> find db.users.find() Get all documents Get all users find(<filterObject>) db.users.find({ name: “Kyle” }) db.users.find({ “address.street”: “123 Main St” }) Find all documents that match the filter object Get all users with the name Kyle Get all users whose adress field has a street field with the value 123 Main St find(<filterObject>, <selectObject>) db.users.find({ name: “Kyle” }, { name: 1, age: 1 }) db.users.find({}, { age: 0 }) Find all documents that match the filter object but only return the field specified in the select object Get all users with the name Kyle but only return their name, age, and _id Get all users and return all columns except for age findOne db.users.findOne({ name: “Kyle” }) The same as find, but only return the first document that matches the filter object Get the first user with the name Kyle countDocuments db.users.countDocuments({ name: “Kyle” }) Return the count of the documents that match the filter object passed to it Get the number of users with the name Kyle Update Each of these commands is run on a specific collection db.<collectionName>.<command> updateOne db.users.updateOne({ age: 20 }, { $set: { age: 21 } }) Update the first document that matches the filter object with the data passed into the second parameter which is the update object Update the first user with an age of 20 to the age of 21 updateMany db.users.updateMany({ age: 12 }, { $inc: { age: 3 } }) Update all documents that matches the filter object with the data passed into the second parameter which is the update object Update all users with an age of 12 by adding 3 to their age replaceOne db.users.replaceOne({ age: 12 }, { age: 13 }) Replace the first document that matches the filter object with the exact object passed as the second parameter. This will completely overwrite the entire object and not just update individual fields. Replace the first user with an age of 12 with an object that has the age of 13 as its only field