SQLTIP－－10進数から2進数へ、2進数から10進数へ

-- 10進数から 2進数へ
SELECT REPLACE (MAX (SYS_CONNECT_BY_PATH (bit, ',')), ',') bin
FROM (SELECT COUNT (*) OVER () - LEVEL + 1 level#,
DECODE (TRUNC (deci / POWER (2, LEVEL)),
ROUND (deci / POWER (2, LEVEL)), 0,
1
) bit
FROM (SELECT 699 deci
FROM DUAL)
CONNECT BY POWER (2, LEVEL - 1) <= deci)
START WITH level# = 1
CONNECT BY PRIOR level# = level# - 1
/

-- 2進数から 10進数へ
SELECT SUM (SUBSTR (bin, LEVEL, 1) * POWER (2, LENGTH (bin) - LEVEL)) deci
FROM (SELECT 11101 bin
FROM DUAL)
CONNECT BY LEVEL <= LENGTH (bin)
/