Also:

https://sive.rs/pg2 - Simplify: move code into database functions

https://sive.rs/pg - PostgreSQL example of self-contained stored procedures

some linked examples: https://github.com/sivers/store/tree/master/store/functions

I like this idea in theory ... although it would cause me to need to know a lot more SQL, which is a powerful but hostile language :-/

I care about factoring stuff out into expressions / functions and SQL fails in that regard ...

https://www.scattered-thoughts.net/writing/against-sql/

It's hard to imagine doing this with a ton of duplication. I have written SQL by hand and there are probably more confusing corners than in shell, which is saying a lot!