> It’s interesting how much SQL, a declarative language,

I think this is the main mistake. SQL is not declarative language, is a high-level DSL:

    1 + 1 = 2 //most PLs
    SELECT 1 + 1 = 2 //SQL
    SET 1 + 1 = 2    //TCLish
    [1, 2] | sum = 2 //Functional
    <span>1</span><span>+</span><span>1</span> = NOT 2! //HTML, a TRUE declarative language!

The main issues that causes this is that SQL is most of the time a little piece disconnected here and there. You don't see how is so imperative and functional until you write manually a big .sql file.

Also, is crippled intentionally, so you don't use it for "regular" programming task (ie, not real way to do print("hello world")!.

I start with FoxPro/dBASE and never develop this disconnect because for me, in Fox, SQL was just another sub-dialect of Fox, that was a "full" programming language. So every-time I do:

    SELECT * FROM customer WHERE code = 1
    SCAN customer WHILE code = 1 //Equivalent Fox CMD
        ?customer
    ENDSCAN 

And similar how in Fox you know that your filters and sort depend on indexes then the same with SQL.

I still look SQL and see it imperatively and have a good grasp on how everything execute (ie: at least until the query planner disagree with me!).