Question

此查询出错：

select ep, 
  case
    when ob is null and b2b_ob is null then 'a'
    when ob is not null or b2b_ob is not null then 'b'
    else null
  end as type,
  sum(b2b_d + b2b_t - b2b_i) as sales
from table
where ...
group by ep, type

错误：ORA-00904：“TYPE”：标识符无效

当我使用group by ep运行时，错误消息变为：

ORA-00979：不是GROUP BY表达式

如果删除行sum(b2b_d+b2b_t-b2b_i) as sales和group by ...，整个查询都可以正常工作，因此问题应与SUM和GROUP BY函数相关。我怎样才能做到这一点？在此先感谢您的帮助。

Answer 1

不幸的是，SQL不允许您在GROUP BY子句中使用列别名，因此您必须像这样重复整个CASE：

select ep, 
  case
    when ob is null and b2b_ob is null then 'a'
    when ob is not null or b2b_ob is not null then 'b'
    else null
  end as type,
  sum(b2b_d + b2b_t - b2b_i) as sales
from table
where ...
group by ep,
  case
    when ob is null and b2b_ob is null then 'a'
    when ob is not null or b2b_ob is not null then 'b'
    else null
  end

或使用这样的内嵌视图：

select ep, 
  type,
  sum(b2b_d + b2b_t - b2b_i) as sales
from
( select ep, 
    case
      when ob is null and b2b_ob is null then 'a'
      when ob is not null or b2b_ob is not null then 'b'
      else null
    end as type,
    b2b_d,
    b2b_t,
    b2b_i
  from table
  where ...
)
group by ep, type

我无法使此查询与SUM函数一起使用

1 个答案: