求一计算数值的 SQL 语句

Question

有A,B两列,按以下原则计算值
若A,B同时为0则取0,
否则若A,B之一为0 则取1
其余情况取 A-B/A求SQL 语句
谢谢

Answer 1

SELECT
DECODE(A,0,
DECODE(B,0,0,1),
DECODE(B,0,1,A-B/A)
) AS result
FROM TBL;

Answer 2

SELECT
DECODE(A,0,
  DECODE(B,0,0,1),   -- A=0 进一步判断B 若B=0 则值为0 否则为1
  DECODE(B,0,1,A-B/A) -- A<>0 进一步判断B 若B=0 则值为1 否则表名AB均非0 取A-B/A
) AS result
FROM TBL;

Answer 3

select 
decode((sign(abs(a))+sign(abs(b))),0,0,1,1,(a-b)/a) value
from table;

Answer 4

select decode(a,0,decode(b,0,0,1),decode(b,0,1,(a-b)/a)) from table