docs(database): add switch form PostgreSQL to MySQL

Author: Shchepotin

docs/database.md

@@ -24,6 +24,7 @@
   - [Max connections](#max-connections)
 - [Performance optimization (MongoDB + Mongoose)](#performance-optimization-mongodb--mongoose)
   - [Design schema](#design-schema)
+- [Switch PostgreSQL to MySQL](#switch-postgresql-to-mysql)
 
 ---
 
@@ -291,6 +292,108 @@ Designing schema for MongoDB is completely different from designing schema for r
 1. [MongoDB Schema Design Anti-Patterns](https://www.mongodb.com/developer/products/mongodb/schema-design-anti-pattern-massive-arrays)
 1. [MongoDB Schema Design Best Practices](https://www.mongodb.com/developer/products/mongodb/mongodb-schema-design-best-practices/)
 
+## Switch PostgreSQL to MySQL
+
+If you want to use MySQL instead of `PostgreSQL`, you can make the changes after following the complete guide given [here](installing-and-running.md).
+
+Once you have completed all the steps, you should have a running app.
+![image](https://github.com/user-attachments/assets/ec60b61a-65e6-43e2-9bcf-72dad4c8a9fa)
+
+If you've made it this far, it only requires a few changes to switch from `PostgreSQL` to `MySQL`.
+
+**Change the `docker-compose.yml` to the following:**
+
+`.env`
+
+```env
+DATABASE_TYPE=mysql
+# set "localhost" if you are running app on local machine
+# set "mysql" if you are running app on docker
+DATABASE_HOST=localhost
+DATABASE_PORT=3306
+DATABASE_USERNAME=root
+DATABASE_PASSWORD=secret
+DATABASE_NAME=app
+```
+
+`docker-compose.yml`
+
+```yml
+services:
+  mysql:
+    image: mysql:9.2.0
+    ports:
+      - ${DATABASE_PORT}:3306
+    volumes:
+      - mysql-boilerplate-db:/var/lib/mysql
+    environment:
+      MYSQL_USER: ${DATABASE_USERNAME}
+      MYSQL_PASSWORD: ${DATABASE_PASSWORD}
+      MYSQL_ROOT_PASSWORD: ${DATABASE_PASSWORD}
+      MYSQL_DATABASE: ${DATABASE_NAME}
+
+  # other services here...
+
+volumes:
+  # other volumes here...
+  mysql-boilerplate-db:
+```
+
+After completing the above setup, run Docker with the following command:
+
+```bash
+docker compose up -d mysql adminer maildev
+```
+
+All three services should be running as shown below:
+
+![image](https://github.com/user-attachments/assets/73e10325-66ed-46ca-a0c5-45791ef0750f)
+
+Once your services are up and running, you're almost halfway through.
+
+Now install the MySQL client:
+
+```bash
+npm i mysql2 --save
+```
+
+**Delete the existing migration file and generate a new one with the following script:**
+
+```bash
+npm run migration:generate -- src/database/migrations/newMigration --pretty=true
+```
+
+Run migrations:
+
+```bash
+npm run migration:run
+```
+
+Run seeds:
+
+```bash
+npm run seed:run:relational
+```
+
+Run the app in dev mode:
+
+```bash
+npm run start:dev
+```
+
+Open <http://localhost:3000>
+
+To set up Adminer:
+
+Open the running port in your browser.
+Open <http://localhost:8080>
+
+![image](https://github.com/user-attachments/assets/f4b86daa-d93f-4ae9-a9e3-3c29bb3bba9d)
+
+Running App:
+![image](https://github.com/user-attachments/assets/5dc0609d-5f6d-4176-918d-1744906f4f88)
+![image](https://github.com/user-attachments/assets/ff2201a6-d834-4c8b-9ab7-b9413a0a95c1)
+
 ---
 
 Previous: [Command Line Interface](cli.md)