MariaDB 10.2

By using db<>fiddle, you agree to license everything you submit by Creative Commons CC0.

set @str = ' '
CREATE FUNCTION some_char_length( str CHAR(1))
RETURNS int
LANGUAGE SQL
no SQL

return  char_length(str)
select some_char_length( ' ')

some_char_length( ' ')

0

select char_length(@str)

char_length(@str)

1

select char_length(' ')

char_length(' ')

1