CREATE TABLE test(a NUMBER(5),b NUMBER(5),c NUMBER(5));
INSERT INTO test VALUES (100,NULL,null);
INSERT INTO test VALUES (null,200,null);
INSERT INTO test VALUES (300,NULL,null);
COMMIT;

SELECT column_name FROM 
(
  SELECT 'A'column_name,Max(Length(a))column_len FROM test UNION ALL 
  SELECT 'B'column_name,Max(Length(b))column_len FROM test UNION ALL 
  SELECT 'C'column_name,Max(Length(c))column_len FROM test 
)WHERE column_len IS NULL;

------解决方案--------------------

怕是要用PL/SQL哦
这样是否可以：
SQL code
DECLARE 
CURSOR temp IS SELECT COLUMN_NAME FROM ALL_TAB_COLUMNS WHERE TABLE_NAME=Upper('TEST');
v_num NUMBER;
BEGIN
  FOR i IN temp 
  LOOP
    execute immediate 'SELECT Count(*) FROM test WHERE '||i.COLUMN_NAME||' IS NOT null' INTO v_num; 
    IF v_num=0 THEN 
      Dbms_Output.put_line('==columns that have no data=='||i.COLUMN_NAME);
    END IF; 
    NULL; 
  END LOOP;
END;