What are they teaching then? I mean, if you're doing a backend - and I don't mean tiny wrapper that wraps user input into queries, I mean the database engine it

What are they teaching then? I mean, if you're doing a backend - and I don't mean tiny wrapper that wraps user input into queries, I mean the database engine itself - it's Java/Scala or C++ (hopefully not C)? Maybe Go? What else do they choose to teach for heavy industrial backend use?