Very true, and I would agree, but why would you define a column that allows only a single character between 'A'-'Z' to be anything other than char(1) or varchar(1) ?

Very interested as to why the  LIKE '[A-Z]' statement in preference to the BETWEEN. I selected the BETWEEN assuming less resource, and more explicit in its functionality.

Yes you can do it with SQL, but I don't know

wether I would do it this way ....

SELECT CASE

...