Function to allow only printable ASCII in data

Question

Hi,
In my CSV upload utility, I've implemented various error checking functions (not a number, not a valid date, not null... etc.), but today I found some strange characters in customer's DB, which was uploaded previously by someone else using sqlldr. Those characters look like small squares from sql developer, so I'm guessing the users had cut-and-paste characters from a different language or special symbols (like the trademark character cut out from Word).
I'd like to make a function or procedure to check for such characters. Basically I want to only include printable characters found only on an English keyboard. Are there any SQL or PL/SQL functions to check for this? Would the regexp_like function be helpful? If so then I'll probably need a reference table that translate between a character and it's chr(x) number for checking.
Many thanks.

Answer 1

Have you tried writing a loop to identify the squares in your character set?
declare
begin
for i in 0...255 loop
dbms_output.put_line(i);
dbms_output.put_line(chr(i));
end loop;
/