MySQL：子查询中的总和值

Question

我有关于学校体育的信息，包括学校、季节、现金流和 cashflow_group 的表格。我正在尝试查询在用户指定范围内的一个或多个给定 cashflow_groups 中拥有现金流的所有学校。我需要在同一个查询中查询多个不同的类别。我有麻烦了。

我的查询如下。我这样做的原因是我可以对多个现金流组进行求和，我认为它有效，直到我仔细观察并发现它将所有学校的现金流量求和为total_cashflow_amount，而每个学校应该具有不同的总计，即其相关现金流行的总和。

SELECT distinct schools.*, 
  (SELECT sum(`cashflows`.amount) AS cf FROM `schools` 
  INNER JOIN `seasons` ON seasons.school_id = schools.id 
  INNER JOIN `cashflows` ON cashflows.season_id = seasons.id 
  INNER JOIN `cashflow_groups` ON `cashflow_groups`.id = `cashflows`.cashflow_group_id 
  WHERE ((`cashflow_groups`.id = 12) AND (`seasons`.`year` = 2010))) AS total_branding_cashflow 
FROM `schools` 

INNER JOIN `seasons` ON seasons.school_id = schools.id 
INNER JOIN `cashflows` ON cashflows.season_id = seasons.id 
INNER JOIN `cashflow_groups` ON `cashflow_groups`.id = `cashflows`.cashflow_group_id 
INNER JOIN `seasons` seasons_schools ON seasons_schools.school_id = schools.id 
WHERE (`seasons`.`year` = 2010) 
GROUP BY schools.id 
HAVING (total_branding_cashflow BETWEEN 50000000 AND 100000000) 
ORDER BY schools.name ASC LIMIT 0, 50

在此查询中，total_branding_cashflow 是所有学校的总计。我不知道如何在子查询中单独获取每所学校的总数。

就目前情况而言，我得到的结果就像

| school.id | … | total_branding_cashflow |
|     2     |   |       900000            |
|     5     |   |       900000            |

我想要的那样，

| school.id | … | total_branding_cashflow |
|     2     |   |       500000            |
|     5     |   |       400000            |

在子查询中添加 GROUP BY 可以在单独的行中给出每所学校现金流的总和，但子查询仅在给出单行时才起作用，所以这不会帮我。

我缺少什么？我使用子查询的原因是我希望能够同时查找多个不同的 cashflow_groups，如下所示：

SELECT distinct schools.*, 
  (SELECT sum(`cashflows`.amount) AS cf FROM `schools` 
  INNER JOIN `seasons` ON seasons.school_id = schools.id 
  INNER JOIN `cashflows` ON cashflows.season_id = seasons.id 
  INNER JOIN `cashflow_groups` ON `cashflow_groups`.id = `cashflows`.cashflow_group_id 
WHERE ((`cashflow_groups`.id = 12) AND (`seasons`.`year` = 2010)) ) AS total_branding_cashflow, 
  (SELECT sum(`cashflows`.amount) AS cf FROM `schools` 
  INNER JOIN `seasons` ON seasons.school_id = schools.id 
  INNER JOIN `cashflows` ON cashflows.season_id = seasons.id 
  INNER JOIN `cashflow_groups` ON `cashflow_groups`.id = `cashflows`.cashflow_group_id 
WHERE ((`cashflow_groups`.id = 1) AND (`seasons`.`year` = 2010)) ) AS total_ticket_sales_cashflow,
  (SELECT sum(`cashflows`.amount) AS cf FROM `schools` 
  INNER JOIN `seasons` ON seasons.school_id = schools.id 
  INNER JOIN `cashflows` ON cashflows.season_id = seasons.id 
  INNER JOIN `cashflow_groups` ON `cashflow_groups`.id = `cashflows`.cashflow_group_id 
WHERE ((`cashflow_groups`.id = 7) AND (`seasons`.`year` = 2010)) ) AS total_university_cashflow 
FROM `schools` 
INNER JOIN `seasons` ON seasons.school_id = schools.id 
INNER JOIN `cashflows` ON cashflows.season_id = seasons.id 
INNER JOIN `cashflow_groups` ON `cashflow_groups`.id = `cashflows`.cashflow_group_id 
INNER JOIN `seasons` seasons_schools ON seasons_schools.school_id = schools.id 
WHERE (`seasons`.`year` = 2010) 
GROUP BY schools.id 
HAVING (total_branding_cashflow BETWEEN 50000000 AND 100000000) AND 
       (total_ticket_sales_cashflow BETWEEN 50000000 AND 100000000) AND 
       (total_university_cashflow BETWEEN 0 AND 10000000) 
ORDER BY schools.name ASC LIMIT 0, 50

我认为我无法使用不在其自己的子查询中的 SUM 来执行此操作。我正在开发一个 Rails 应用程序，并且可能会想出一种通过 ruby​​ 代码来做到这一点的方法。但这似乎不对，如果可能的话，我更愿意用 SQL 来记录它。谢谢！

Answer 1

一些建议：

• 加入季节一次。连接会导致左表中的行重复，因此可以通过 sum 聚合将它们求和两次。如有疑问，请针对示例学校运行不带 group by 的查询。
• 您必须使用类似 inner_schools.id = external_schools.id 的内容将子查询与外部查询相关联，
• 但据我所知，您根本不需要子查询

：

SELECT  schools.*
,       sum(cashflows.amount) total_branding_cashflow
FROM    schools
JOIN    seasons
ON      seasons.school_id = schools.id 
        and seasons.year = 2010
JOIN    cashflows
ON      cashflows.season_id = seasons.id 
        and cashflow_group_id = 12
GROUP BY 
        schools.id 
HAVING  total_branding_cashflow BETWEEN 50000000 AND 100000000

例如 多个类别，您可以使用案例：

SELECT  schools.*
,       sum(case when cashflow_group_id = 1 then cashflows.amount end) total1
,       sum(case when cashflow_group_id = 12 then cashflows.amount end) total12
FROM    schools
JOIN    seasons
ON      seasons.school_id = schools.id 
        and seasons.year = 2010
JOIN    cashflows
ON      cashflows.season_id = seasons.id 
GROUP BY 
        schools.id