MongoDB Database Deletion Using MongoShell

MongoDB organizes data into databases, collections, and documents with a flexible, schema-flexible model.

• NoSQL database with dynamic schema support.
• Databases group related collections.
• Documents are the basic data units.
• Adapts easily to changing data structures.

Database in MongoDB

A MongoDB database groups collections that store documents and can host multiple databases on one server.

• Database acts as a container for collections.
• Collections are like tables in relational databases.
• Stores data as documents.
• Supports multiple databases per server.
• Scales for diverse application needs.

Collection in MongoDB

A collection groups related documents in MongoDB without enforcing a fixed schema.

• Similar to tables in relational databases.
• Does not enforce a fixed schema.
• Stores multiple related documents.
• Documents can have different fields.

[
    {
        "Name": "Alen",
        "Age": 24,
        "Gender": "Male"
    },
    {
        "Name": "Kim",
        "Age": 32,
        "Gender": "Male"
    },
    {
        "Name": "Lee",
        "Age": 21,
        "Gender": "Female"
    }
]

Document in MongoDB

A document is MongoDB’s basic data unit, stored as field–value pairs with flexible structure.

• Smallest unit of data in MongoDB.
• Stored as field–value pairs.
• Structure can vary within a collection.
• Enabled by dynamic schema design.

{
  "Name": "Adam",
  "Age": 24,
  "Gender": "Male"
}

MongoDB Shell (mongosh)

MongoDB Shell (mongosh) is a command-line JavaScript interface for managing and querying MongoDB.

• Interactive CLI for MongoDB operations.
• Supports querying and updating data.
• Used for database and collection management.
• Helpful for development and administration.

Deleting a Database in MongoDB

Deleting a database in MongoDB is a straightforward process using the db.dropDatabase() command. This command permanently removes the currently selected database along with all its collections and documents.

Syntax

 db.dropDatabase()

• Drops the currently selected database.
• Permanently deletes all its collections and data.
• Deletes the currently selected database (the default context is ‘test’ if no database is explicitly selected).
• Operation cannot be undone.

Example 1: To delete the userDB database, first select it using the use userDB command.

Query:

// Step 1: Select the database to delete
use userDB

// Step 2: Drop the selected database
db.dropDatabase()

Output:

This confirms that the database userDB has been deleted.

Example 2: Delete a Database that is not currently selected (by switching to it first).

Follow these steps:

1. Check the Current Database:

db

This command returns the name of the currently selected database.

2. List All Databases:

show dbs

This command lists all the available databases on the MongoDB server.

3. Select the Database to Delete:

use adminDB

Replace adminDB with the name of the database you want to delete.

4. Delete the Selected Database:

db.dropDatabase() 

This confirms that the adminDB database has been deleted successfully.

Important Points to Remember

Here are some important points to be remembered:

• Deleting the Default Database: If no database is selected, the db.dropDatabase() command deletes the default test database.
• Irreversible Operation: Deleting a database is a permanent operation. Ensure you have backups if required.
• Admin Privileges: Ensure you have the necessary permissions to delete databases.
• No Impact on Other Databases: Deleting a database does not affect other databases on the same server.