Oracle查找乱码的数据

SELECT COL_NAME
FROM table_name
  WHERE ASCIISTR(COL_NAME) LIKE '%\FFFD%'  
OR COL_NAME IS NOT NULL AND ASCIISTR(COL_NAME) IS NULL
OR ASCII(SUBSTR(ASCIISTR(COL_NAME),1,1)) BETWEEN 2 AND 31
OR LENGTHB(COL_NAME)>LENGTHB(ASCIISTR(COL_NAME));