Can we change the MongoDB to MySQL in MEAN stack?

Yes, it is possible to replace MongoDB with MySQL in the MEAN stack. The MEAN stack is a combination of technologies (MongoDB, Express.js, Angular, Node.js) that work together to build web applications. MongoDB is a NoSQL database, while MySQL is a relational database. If you decide to switch from MongoDB to MySQL, you'll need to make adjustments to your database layer and possibly some parts of your application logic.

Here are the general steps to replace MongoDB with MySQL in a MEAN stack application:

1. Database Schema:

   • MongoDB is a NoSQL database, and its data is stored in a flexible, JSON-like format called BSON. MySQL, being a relational database, requires a predefined schema. You'll need to design a relational database schema for your application and migrate the data from MongoDB to MySQL.

2. Backend Changes (Node.js and Express):

   • Adjust the backend code that interacts with the database. Replace MongoDB-specific code (such as Mongoose ODM) with MySQL-compatible code. You'll need to use a MySQL library or ORM (Object-Relational Mapping) to interact with the MySQL database.

3. API Endpoints:

   • Modify the API endpoints to handle MySQL queries instead of MongoDB queries. This may involve changes to how data is retrieved, updated, and deleted.

4. Data Validation:

   • MongoDB and MySQL may have different data types and validation requirements. Update your data validation logic to match the requirements of MySQL.

5. Angular Frontend:

   • If your Angular application interacts directly with the database (for example, through RESTful API calls), you may need to adjust the frontend code to handle MySQL-compatible data structures and queries.

6. Testing:

   • Thoroughly test your application after making the changes. Verify that data is being stored and retrieved correctly from MySQL. Pay attention to potential differences in data types, indexing, and querying behavior.

7. Deployment:

   • Update your deployment scripts or configurations to use MySQL instead of MongoDB. Ensure that the server is configured to connect to the MySQL database.

8. Security Considerations:

   • Update security measures, such as authentication and authorization, to match the requirements of MySQL. Ensure that your MySQL server is properly secured.

Keep in mind that this transition may involve significant changes to your application, and you should plan accordingly. Additionally, it's a good practice to create backups of your data before migrating to a new database system to avoid data loss.