Chapter 4: MongoDB mongosh Create Database

What is MongoDB mongosh Create Database?

This is super common confusion for beginners, so let’s clear it 100% like a patient teacher sitting next to you with a notebook.

Big Truth First (Write this down!)

MongoDB does NOT have a direct “CREATE DATABASE” command like MySQL (CREATE DATABASE shop;) or PostgreSQL.

Instead, MongoDB follows a “lazy creation” philosophy:

A database (and even a collection) is automatically created the first time you store data in it.

You don’t create an empty database upfront — MongoDB waits until you actually put something inside.

And the main way you “tell” MongoDB which database you want to work with (and create it if missing) is the use <database_name> command inside mongosh.

So when people say “mongosh Create Database“, what they really mean is:

How to create / switch to a database using mongosh (the modern MongoDB shell)

Step-by-Step Explanation – Like We’re Doing It Together

1. Connect to mongosh first (Assuming you already have Atlas or local MongoDB running — from our Getting Started class)

   Bash

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   mongosh "mongodb+srv://youruser:yourpassword@cluster0.abcde.mongodb.net/"

   You land in the default/test database or whatever your connection string specifies.

2. Check current database

   Type:

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   db

   Output example: test (default when nothing is selected)

3. See existing databases

   JavaScript

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   show dbs

   You might see:

   text

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   admin          0.000GB config         0.000GB local          0.000GB

   Your new one won’t appear yet — because it’s empty!

4. The Magic Command: use

   JavaScript

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   use myHyderabadShop

   Output:

   text

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   switched to db myHyderabadShop

   • If myHyderabadShop already existed → it just switches to it.
   • If it did NOT exist → MongoDB prepares it (but doesn’t physically create files yet).

   At this moment — still no database is visible in show dbs!

5. Actually Create It (by inserting data)

   This is the key step most tutorials emphasize:

   JavaScript

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   db.products.insertOne({   name: "Hyderabadi Dum Biryani",   price: 350,   spicyLevel: "Medium",   available: true })

   Output something like:

   text

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   {   acknowledged: true,   insertedId: ObjectId('67ab1234cdef567890abcdef') }

   NOW — magic happens!

   Run again:

   JavaScript

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   show dbs

   Now you see:

   text

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   admin          0.000GB config         0.000GB local          0.000GB myHyderabadShop  0.000GB   ← appeared!

   → Database physically created only after first document was inserted.

6. Alternative ways people create database + collection in one go

   JavaScript

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   use blogApp   db.posts.insertMany([   { title: "Valentine Special Biryani", content: "Love is spicy!", likes: 42 },   { title: "MongoDB Tips", content: "use + insert = create", likes: 15 } ])

   Same effect — database blogApp + collection posts created instantly.

Quick Comparison Table – MySQL vs MongoDB (Very Helpful!)

Important Notes (Don’t Miss These!)

• Database names are case-sensitive in most cases (but avoid weird characters).
• You cannot create empty databases that stay forever — if you use newDb but never insert anything → it disappears after restart / won’t show in show dbs.
• In MongoDB Atlas UI → you can create database + collection visually (Create Database button) → that inserts a dummy doc behind the scenes.
• In code (Node.js / Python) → same rule: first insertOne / insertMany creates db + collection.

Mini Exercise – Do This Right Now!

1. Open mongosh
2. show dbs
3. use class2026Feb14
4. db.students.insertOne({ name: “Rahul”, city: “Hyderabad”, mood: “Learning MongoDB ❤️” })
5. show dbs → see your new database!
6. db → confirm you’re in class2026Feb14
7. db.students.find().pretty()

Done! You just created your first database the MongoDB way.

Understood beta? 😄

This is one of those “aha!” moments in MongoDB — once it clicks, you never forget.

Next class — what do you want?

• How to create collection explicitly (with options like validator, capped)?
• Drop database / drop collection safely?
• List all collections in current db?
• Work with multiple databases in one session?
• Or jump to real project — like a simple student management system?

Tell me — class is continuing! 🚀