I'm working on php project with mysql and xampp, the purpose of this app will be database operations(like insert/update/view/delete) and i want to host this on web. Also i have a little GUI to help the user make the operationsv.
I found that AWS EC2 is a good choice but i dont know how should i choose best specifications for this instance to have an idea for the price? How many memory i need just for those operations?
You should evaluate the most important performance metrics first for your application and decide accordingly which EC2 instance type to choose from.
For applications that benefit from a low cost per CPU, you should try compute-optimized instances (C1 or CC2) first.
For applications that require the lowest cost per GiB of memory, It is recommended to use memory-optimized instances (M2 or CR1).
I would recommend you to use AWS RDS service for database instead of installing MySQL on EC2 instance.
For more details https://aws.amazon.com/blogs/aws/choosing-the-right-ec2-instance-type-for-your-application/