oracle的与运算符号是什么？

Question

用UTL_RAW包，举例如下：
SQL> select to_number(utl_raw.bit_and(to_char(256,'fm000x'),to_char(128,'fm000x')),'xxxx')
  2  from dual;TO_NUMBER(UTL_RAW.BIT_AND(TO_CHAR(256,'FM000X'),TO_CHAR(128,'FM000X')),'XXXX')
------------------------------------------------------------------------------
                                                                             0SQL> select to_number(utl_raw.bit_and(to_char(256,'fm000x'),to_char(256,'fm000x')),'xxxx')
  2  from dual;TO_NUMBER(UTL_RAW.BIT_AND(TO_CHAR(256,'FM000X'),TO_CHAR(256,'FM000X')),'XXXX')
------------------------------------------------------------------------------
                                                                           256SQL> select to_number(utl_raw.bit_or(to_char(256,'fm000x'),to_char(128,'fm000x')),'xxxx') 
  2  from dual;TO_NUMBER(UTL_RAW.BIT_OR(TO_CHAR(256,'FM000X'),TO_CHAR(128,'FM000X')),'XXXX')
-----------------------------------------------------------------------------
                                                                          384SQL> select to_number(utl_raw.bit_or(to_char(256,'fm000x'),to_char(256,'fm000x')),'xxxx') 
  2  from dual;TO_NUMBER(UTL_RAW.BIT_OR(TO_CHAR(256,'FM000X'),TO_CHAR(256,'FM000X')),'XXXX')
-----------------------------------------------------------------------------
                                                                          256