Question

以下两个查询可以自己工作：

select coalesce(sum(shares*cps),0.0)  from 
transactions
where usr = 1
and (type = 'C'
or type  = 'S')

select coalesce(sum(shares*cps),0.0) from 
transactions
where usr = 1
and (type = 'W'
or type  = 'B')

我如何结合它们以得到它们之间的区别？像这样：

select coalesce(sum(a.shares*a.cps),0.0) - coalesce(sum(b.shares*b.cps),0.0)   from 
      (select * from transactions
                where usr = 1
                  and (type = 'C'
                   or type  = 'S')) as a,
      (select * from transactions
                where usr = 1
                  and (type = 'W'
                   or type  = 'B')) as b;

返回的值为0。第一个合并返回200000.00，第二个合并返回0.00

Answer 1

您可以使用SYSDUMMY1，这是一个虚拟表，其中有一条记录，可用于选择简单值，在这种情况下，这是两个总和之差：

select 
( select coalesce(sum(shares*cps),0.0)  from 
  transactions
  where usr = 1
  and (type = 'C'
       or type  = 'S')) -
( select coalesce(sum(shares*cps),0.0) from 
  transactions
  where usr = 1
  and (type = 'W'
       or type  = 'B')) as DIFFERENCE
from SYSIBM.SYSDUMMY1

两个聚合值之间的derby sql差异或如何组合两个sql语句

1 个答案: