包含AS的SQL SELECT语句

Question

我有SQL查询：

select title, scale / next_scale, c
from ( select title, scale, scale*D0 AS c, 
              lead(scale) over(partition by title order by scale asc) as next_scale,
              row_number() over(partition by title order by scale asc) as agg_row
       from signatures
     ) agg
where agg_row = 1;

并且它按预期工作。 但是，我真正希望排序的“标度”值是几列之间的算术运算，因此我尝试使用AS子句（如上所示）并将查询修改为：

select title, scale / next_scale, c
from ( select title, scale, scale*D0 AS c, 
              lead(scale) over(partition by title order by c asc) as next_scale,
              row_number() over(partition by title order by c asc) as agg_row
       from signatures
     ) agg
where agg_row = 1;

但是，它在ORDER BY c处失败。 为什么是这样？ 我可以用ORDER BY scale*D0代替它，效果很好。 但是，我最终将要使用这样的术语： scale*D0*D1*D2*...*D100 ; 而且我不需要计算3次不同的时间-更不用说查询的物理长度了。 我希望具有scale*D0*D1*D2*...*D100 AS c ，然后具有ORDER BY c 。

这可能吗？

我正在使用PostgreSQL。

非常感谢，布雷特

Answer 1

在子查询中计算c ：

select title, scale / next_scale, c
from ( select title, scale, c, 
              lead(scale) over(partition by title order by c asc) as next_scale,
              row_number() over(partition by title order by c asc) as agg_row
       from (select title, scale, scale * D0 AS c from signatures) signatures_calc
     ) agg
where agg_row = 1;

Answer 2

您可以按列的序号ORDER BY：

select title, scale / next_scale, c
from ( select title, scale, scale*D0 AS c, 
          lead(scale) over(partition by title order by scale asc) as next_scale,
          row_number() over(partition by title order by scale asc) as agg_row
   from signatures
 ) agg
where agg_row = 1
order by 3;

Answer 3

下订单时是子查询，应填写帐单

select title, scale / next_scale, c
from ( select title, scale, scale*D0 AS c, 
          lead(scale) over(partition by title order by scale asc) as next_scale,
          row_number() over(partition by title order by scale asc) as agg_row
       from signatures
       order by 3
 ) agg
where agg_row = 1;