Build Database for Existing Website (PHP and .NET )

Need to add a database for the website and be accessible online. The website consists of PHP and .NET languages. The website is https://aamcodrivingschool.com/. The reason for the database is to keep track of students' information such as registration, payments, their name, address, email....... I want to have this integrated easy and simple way possible. This company is growing and there will be more projects. Looking for someone or a team for a long-term relationship and ensuring all the requirements are taken care of. Need professional and creative team/individual with strong expertise in coding language.