方法说明：
B.2.2 UTL_RAW.BIT_AND
UTL_RAW.BIT_AND performs a bitwise logical AND operation on two raw values. If the values have different lengths, then the AND operation is terminated after the last byte of the shorter of the two values. The unprocessed portion of the longer value is appended to the partial result to produce the final result. The length of the resulting value equals the longer of the two input values.