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我正在尝试向包含总和（或任何其他操作，例如平均值）作为最后一行的 SQL 选择查询添加一行。在这方面，它类似于 GROUP BY ... WITH ROLLUP。

首先：假设我有一个表 t，其中包含字段 ID、A、B 和 C，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) );

但是，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可以只指定一次条件来完成相同的结果。

提前致谢。

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2 回答 2

2

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
于 2012-12-12T23:21:57.143 回答
2

好吧，没有平均值，您可以这样做：

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

我会写成：

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

我不确定汇总如何与 avg 一起使用，因此最终版本是：

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
于 2012-12-13T02:41:23.763 回答