Of course it's possible. But you are not beholden to using a database server to use SQL. The app servers can speak SQL too. And, in some cases, should. It is sometimes the right tool for the job.
But if GraphQL is a good fit for your situation, SQL is not. Aside from both enabling ad-hoc execution, there is little overlap between them. They are designed to solve different problems.
But if GraphQL is a good fit for your situation, SQL is not. Aside from both enabling ad-hoc execution, there is little overlap between them. They are designed to solve different problems.