Question

我正在尝试向SQL select查询添加一行，该查询包含一个总和（或任何其他操作，例如平均值）作为最后一行。在这里它类似于GROUP BY ... WITH ROLLUP。

首先：假设我有一个包含字段ID，A，B和C的表t，所有这些都是数字。此外，ID不是唯一的，而是一个类别。我的SELECT查询应该计算这些数字中有多少落在指定范围内。

因此，例如，最终结果将是

(SELECT t.ID, a.ac, b.bc, c.cc FROM t
LEFT JOIN (SELECT COUNT(*) cc,ID FROM t WHERE A BETWEEN 2 AND 4 GROUP BY ID) AS a ON a.ID=t.ID 
LEFT JOIN (SELECT AVG(B) cc,ID FROM t WHERE B BETWEEN 19 AND 40 GROUP BY ID) AS b ON b.ID=t.ID 
LEFT JOIN (SELECT COUNT(*) cc,ID FROM t WHERE C BETWEEN 12 AND 14 GROUP BY ID) AS c ON a.ID=t.ID GROUP BY t.ID) 

union 

(select 'Overall',
 (SELECT COUNT(*) cc FROM t WHERE A BETWEEN 2 AND 4),
 (SELECT AVG(B) cc FROM t WHERE B BETWEEN 19 AND 40),
 (SELECT COUNT(*) cc FROM t WHERE C BETWEEN 12 AND 14) );

然而，这个解决方案并不理想，因为我需要重新说明A，B和C的条件。我想知道是否有一种简单的方法来完成相同的结果，只指定条件一次。< / p>

提前致谢。

Answer 1

我认为没有更简单的解决方案。但我会像这样重写你的查询：

SELECT
  t.ID,
  count(case when A between 2 and 4 then ID end),
  AVG(case when B between 19 and 40 then B end),
  COUNT(case when C between 12 and 14 then id end)
FROM t
GROUP BY ID
UNION
select
  'Overall',
  count(case when A between 2 and 4 then ID end),
  AVG(case when B between 19 and 40 then B end),
  COUNT(case when C between 12 and 14 then id end)
FROM t

Answer 2

嗯，如果没有平均值，你可以这样做：

SELECT t.ID,
       count(case when A between 2 and 4 then ID end),
       AVG(case when B between 19 and 40 then B end),
       COUNT(case when C between 12 and 14 then id end)
FROM t
GROUP BY ID with rollup

我会写作：

SELECT t.ID,
       sum(case when A between 2 and 4 then 1 else 0 end),
       sum(case when B between 19 and 40 then B end)/sum((case when B between 19 and 40 then B end),
       sum(case when C between 12 and 14 then 1 else end)
FROM t
GROUP BY ID with rollup

我不确定汇总是如何与avg一起使用的，所以最终版本是：

select coalesce(t.ID, 'Overall'), Acnt,
       (case when Bcnt > 0 then Bsum/Bcnt end),
       Ccnt
from (select t.ID,
             sum(case when A between 2 and 4 then 1 else 0 end) as Acnt,
             sum(case when B between 19 and 40 then B end) as Bsum,
             sum(case when B between 19 and 40 then B end) as Bcnt,
             sum(case when C between 12 and 14 then 1 else end) as Ccnt
      FROM t
      GROUP BY ID with rollup
     ) t

为每列添加一个包含总计的行

2 个答案: