[oarabbus_]

Honestly, I think it's because a lot of folks go their entire careers avoiding set-based thinking. Many of these folks are talented programmers so I would assume they'd become quite decent at SQL if they devoted time to it. I'm speaking more on the DML side than the DDL side here.

In my experience <20% of developers are good enough to be dangerous with SQL, and maybe 5% what I'd consider adept.

The rest range from "SELECT * is as far as I'll go; where's the ORM" to "why the hell are you using cursors to aggregate"

SQL is powerful, elegant, and reliable. With modern DB support of JSON, ARRAY, statistical functions, and much more, SQL is probably the #1 most underutilized/improperly leveraged tool today. SQL-killers have been coming out for 40 years now and (for its domain!) SQL's lead is pulling farther away if anything.

*yes there are some questionable implementations, so please replace "SQL" with "PostgreSQL" if nonstandard SQL implementations have caused nightmares for you in the past.

[IgorPartola]

The reason isn’t set based thinking avoidance. I think it is because fundamentally we want to work with smart objects and not rows of data in most cases.

[oarabbus_]

More often than not that's a good example of set-based thinking avoidance. The application graveyard is full of projects that felt their transactional data was too sophisticated for "dumb rows" and reinvented an inefficient relational model. I'd love to hear more about these "smart objects" - they're usually not that smart and typically can be represented relationally.

Even for use-cases like graph based models you still find Twitter and Facebook using MySQL to build the graph on top of. It’s simply heavily abstracted for the majority of engineers at those companies (where I'd wager the <20% proficiency in set-based thinking holds true) but it still fundamentally relies on SQL.

[omginternets]

Where can I learn about the relationship between set-theory and SQL?

[oarabbus_]

I'm not too well-versed in the academic/mathematical background of SQL, other than than to say it's closer to relational algebra than Set theory, and the resource to read is probably the 1970 Codd paper: https://www.seas.upenn.edu/~zives/03f/cis550/codd.pdf

SQL does implement the set operations of UNION, INTERSECT, and EXCEPT, but I meant "thinking in sets" more colloquially.

edit: this is more practical than theoretical but the author here actually does a nice job of discussing "set-based" thinking vs. procedural https://www.itprotoday.com/open-source-sql/fangraphs-tags-cl...

[aahortwwy]

Discrete Mathematics with Applications by Epp. Chapters 5, 7, 10.

Fundamentals of Database Systems by Elmasri & Navathe. Part 2.