1. base64 的解密函数
select utl_raw.cast_to_varchar2(utl_encode.base64_decode(utl_raw.cast_to_raw('dGVzdA=='))) from dual

2. base64 的加密函数
select utl_raw.cast_to_varchar2(utl_encode.base64_encode(utl_raw.cast_to_raw('test'))) from dual

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