Your computer is also not a Turing Machine. The regex that you use is not really a regular language. Your functions and logic are not referentially transparent, because well, they have to run on a computer.
But it's useful to learn the foundational mathematics of these things as there is a direct relationship between them.
SQL has semantics that can be understood by relational algebra of relational bags. It's of course not a 1:1 translation, but the mathematical underpinnings are explained there. It's useful to learn the simpler, more abstract thinking tool in order to understand the concrete programming tool.
But it's useful to learn the foundational mathematics of these things as there is a direct relationship between them.
SQL has semantics that can be understood by relational algebra of relational bags. It's of course not a 1:1 translation, but the mathematical underpinnings are explained there. It's useful to learn the simpler, more abstract thinking tool in order to understand the concrete programming tool.