-- 01)letter or digit

DECLARE
    v_char CHAR(1) ;
    v_result VARCHAR(30);
BEGIN
    v_char:=:v_char;
    IF (v_char >= 'A' AND v_char <= 'Z') or (v_char >='a' And v_char <='z') THEN
        v_result := 'Letter';
    ELSIF v_char >= '0' AND v_char <= '9' THEN
        v_result := 'Digit';
    ELSE
        v_result := 'Neither letter nor digit';
    END IF;
    DBMS_OUTPUT.PUT_LINE('The character "' || v_char || '" is a ' ||v_result);
END;