根据表中列值比较大小显示不同结果
我有一个表
select a,b,c from biaotable
我想想要的结果是:
如果 a >c 则显示select a,b,c,(a - c) as d from biaotable
如果 c > b 则显示 select a,b,c,(c - b ) as d from biaotable
请高手帮忙写到一条SQL语句中,谢谢!

------解决方案--------------------
你逻辑混乱了.

a>c和c>b是可共存的条件. 那么这里怎么取?
------解决方案--------------------
如果 a > c 则显示select a,b,c,(a - c) as d from biaotable 
如果 c > b 则显示 select a,b,c,(c - b ) as d from biaotable 

SQL code

select 
*,d=case when a>c then a-c
         when c>b then c-b
     end
from biaotable