在左连接 SQL 语句中选择总和显示的空值答案

【问题标题】：Select sum shown null value in left join SQL statement在左连接 SQL 语句中选择总和显示的空值
【发布时间】：2021-02-01 23:29:12
【问题描述】：

我有三个表，期望结果如下，但我不知道如何更正我的 sql 语句。

select history.company,history.ghacct,rpt_revenue.revenue,rpt_revenue.other, isnull(guest.stay,0) as stay, isnull(guest.nights,0) as nights
from history
left join(select company,count(*) as stay,sum(nights) as nights from guest group by company) guest on guest.company=history.company
left join (select ghacct,sum(revenue) as revenue, sum(other) as other
from rpt_revenue group by ghacct) rpt_revenue on rpt_revenue.ghacct=history.ghacct
where history.type='c' group by history.company, history.ghacct,rpt_revenue.revenue, rpt_revenue.other,guest.stay,guest.nights order by history.company asc;

历史

ghacct company type
33 JOINT LTD 10010205687 c
3B GLOBAL   10010350619 c
3E FASHION  10010244145 c
3P INT'L        10010112089 c

客人

company     stay        nights
33 JOINT LTD    01/01/2009  1
33 JOINT LTD    01/06/2009  1
3B GLOBAL   10/02/2019  2
3E FASHION  09/25/2008  6
3P INT'L        08/26/2009  3
3P INT'L        04/26/2010  9

rpt_revenue

ghacct      revenue other
10010205687 20  10
10010205687 10  10
10010350619 30  2
10010244145 15  3
10010112089 16  8
10010112089 4   2

结果

company     ghacct      revenue other   stay    nights
33 JOINT LTD    10010205687 NULL    NULL    2   2
3B GLOBAL   10010350619 NULL    NULL    1   2
3E FASHION  10010244145 NULL    NULL    1   6
3P INT'L        10010112089 NULL    NULL    2   12

预期结果

company     ghacct      revenue other   stay    nights
33 JOINT LTD    10010205687 30  20  2   2
3B GLOBAL   10010350619 30  2   1   2
3E FASHION  10010244145 15  3   1   6
3P INT'L        10010112089 20  10  2   12

【问题讨论】：

您能解释一下您要达到的目标吗？您现有的查询有什么问题
请格式化您的查询，以便其他人更容易理解它。

标签： sql-server-2000

【解决方案1】：

我认为您当前查询的主要问题在于GROUP BY 子句，它实际上应该只按公司和帐户汇总。此外，您可能希望使用ISNULL 来表示收入和其他金额，因为您已经在为住宿和夜晚这样做了。

SELECT
    h.company,
    h.ghacct,
    ISNULL(rr.revenue, 0) AS revenue,
    ISNULL(rr.other, 0)   AS other,
    ISNULL(g.stay, 0)     AS stay,
    ISNULL(g.nights, 0)   AS nights
FROM history h
LEFT JOIN
(
    SELECT company, COUNT(*) AS stay, SUM(nights) AS nights
    FROM guest
    GROUP BY company
) g
    ON g.company = h.company
LEFT JOIN
(
    SELECT ghacct, SUM(revenue) AS revenue, SUM(other) AS other
    FROM rpt_revenue
    GROUP BY ghacct
) rr
    ON rr.ghacct = h.ghacct
WHERE
    h.type = 'c'
GROUP BY
    h.company,
    h.ghacct
ORDER BY
    h.company;

【讨论】：