--1
select productName1,color1,
       sum(decode(color1,'红',1,0))-sum(decode(color1,'蓝',1,0)) num_
  from product1
 group by productName1,color1
 having sum(decode(color1,'红',1,0)) > sum(decode(color1,'蓝',1,0)); 
--2
select productName1,
       sum(decode(color1,'红',1,0)) 红色rednum ,
       sum(decode(color1,'蓝',1,0)) 蓝色bluenum
  from product1
 group by productName1;

------解决方案--------------------
探讨

非常感谢一楼，但是你的那个1好像只是记录条数而没有涉及到产品的数量，另外那个null值在decode中是怎么处理的？


------解决方案--------------------
SQL code

select productName1,color1,
    sum(decode(color1,'红',nvl(num1,0),0))-sum(decode(color1,'蓝',nvl(num1,0),0)) num_
from product1
group by productName1,color1
having sum(decode(color1,'红',nvl(num1,0),0)) > sum(decode(color1,'蓝',nvl(num1,0),0))