如何在分组查询中添加“总计”行（在 Postgresql 中）？

Question

如何在此 SELECT 的末尾添加一行，以便查看分组行的总数？ （我需要 'money' 和 'requests' 的总数：

SELECT 
    organizations.name || ' - ' || section.name as Section, 
    SUM(requests.money) as money, 
    COUNT(*) as requests
FROM 
    schema.organizations
   -- INNER JOINs omitted --
WHERE 
    -- omitted --
GROUP BY 
    -- omitted --
ORDER BY 
    -- omitted --

运行上述产生：

|*Section*  | *Money* | *Requests*|
|-----------|---------|-----------|
|BMO - HR   |564      |10         |
|BMO - ITB  |14707    |407        |
|BMO - test |15       |7          |

现在我想要在显示的末尾添加一个总数：

|BMO - Total|15286    |424        |

---

我尝试了一些方法，最终尝试将选择包装在 WITH 语句中但失败了：

WITH w as (
    --SELECT statement from above--
)
SELECT * FROM w UNION ALL 
   SELECT 'Total', money, requests from w

这会产生奇怪的结果（我总共得到了四行 - 当应该只有一个时。

任何帮助将不胜感激！

谢谢

Answer 1

您可以通过使用 UNION 查询来实现此目的。在下面的查询中，我添加了一个人工排序列并将联合查询包装在一个外部查询中，以便总和行出现在底部。

[我假设您将添加联接和分组依据子句...]

SELECT section, money, requests FROM  -- outer select, to get the sorting right.

(    SELECT 
        organizations.name || ' - ' || section.name as Section, 
        SUM(requests.money) as money, 
        COUNT(*) as requests,
        0 AS sortorder -- added a sortorder column
     FROM 
        schema.organizations
    INNER JOINs omitted --
    WHERE 
        -- omitted --
    GROUP BY 
        -- omitted --
       --  ORDER BY is not used here


UNION

    SELECT
       'BMO - Total' as section,
        SUM(requests.money) as money, 
        COUNT(*) as requests,
        1 AS sortorder
    FROM 
        schema.organizations
        -- add inner joins and where clauses as before
) AS unionquery

ORDER BY sortorder -- could also add other columns to sort here

Answer 2

https://stackoverflow.com/a/54913166/1666637 答案中的汇总函数可能是一种方便的方法。有关此功能和相关功能的更多信息：https://www.postgresql.org/docs/devel/queries-table-expressions.html#QUERIES-GROUPING-SETS

类似这样的，未经测试的代码

WITH w as (
    --SELECT statement from above--
)
SELECT * FROM w ROLLUP((money,requests))

注意双括号，它们很重要