选择求和显示左连接SQL语句中的空值

如何解决选择求和显示左连接SQL语句中的空值

我有三个表，预期结果如下，但我不知道如何更正我的sql语句。

1st place   2nd place   3rd place   1st place value 2nd place value 3rd place value
factor1     factor2     factor3     1               1               1
factor1     factor2     factor3     1               1               2
factor1     factor2     factor3     1               1               3
…           …           …           …               …               …   
factor8     factor9     factor10    15              15              15

历史

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,guest.stay,guest.nights order by history.company asc;

客人

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

rpt_revenue

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

结果

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

预期结果

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

解决方法

我认为您当前查询的主要问题在于GROUP BY子句，该子句实际上仅应按公司和帐户进行汇总。此外，您可能希望将ISNULL用于收入和其他金额，因为您已经在住宿和住宿期间使用了。

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;