When I was new to engineering management, I took over a project where one of the large components, a claims processing rules engine, was written entirely in SQL

When I was new to engineering management, I took over a project where one of the large components, a claims processing rules engine, was written entirely in SQL. Apparently, the previous manager had assigned that component to a DBA to build and by the time they found out, it was too late in the project to re-write. Anyway... years later my scope had increased to include some mainframe teams working in COBOL. I have always been a big believer that you can't effectively lead a team if you can't do the job, so I dove in and learned COBOL. Now, I am not saying that COBOL and SQL are syntactically similar, but the experience of building in COBOL was very similar to building application logic in SQL. None of the abstractions we are used to, and no real concept of separation of concerns. It was fairly easy to build in, but an absolute nightmare to maintain.