以下为引用的内容：

-----二进制转换十进制-----------------
select sum(data1)
  from (select substr('1101', rownum, 1) * power
(2, length('1101') - rownum) data1
          from dual
        connect by rownum <= length('1101'))

-----八进制转换十进制-----------------
select sum(data1)
  from (select substr('1101', rownum, 1) * power
(8, length('1101') - rownum) data1
          from dual
        connect by rownum <= length('1101'))

-----十六进制转换十进制-----------------
select sum(data1)
  from (select (CASE upper(substr('2D', rownum, 1))
WHEN 'A' THEN '10'
WHEN 'B' THEN '11'
WHEN 'C' THEN '12'
WHEN 'D' THEN '13'
WHEN 'E' THEN '14'
WHEN 'F' THEN '15'
ELSE substr('2D', rownum, 1)
END) * power(16, length('2D') - rownum) data1
from dual
connect by rownum <= length('2D'))