Funny how they say SQL gets it right, but then shows an example which is the opposite of my experience.

From PostgreSQL

    # select '5' = 5;
    ?column?
    --------
    t
    (1 row)

I believe this is standard SQL. Putting something in quotes just means it is a literal, doesn't mean it is a string. Of course if you explicitly cast it to a string, then you get an error. As in:

    select '5'::text = 5;
    ERROR:  operator does not exist: text = integer
    LINE 1: select '5'::text = 5;
                             ^
    HINT:  No operator matches the given name and argument types. You might need to add explicit type casts.

I agree with the premise - SQL gets it right, but perhaps only in PostgreSQL?