Question

我有这张桌子：

table tblCountry 
   name char(30)

table tblSite
   name char(30) primary key not null,
   country char(30) 

table tblDivingClub
   number int
   name char(30)
   country char(30)

table tblDiving
   diving_number int 
   number_of_divers int
   diving_club int
   guide int

我写了这个问题：

select 
    tblSite.name,tblSite.site_length,tblSite.site_depth,
    tblSite.water_type,tblSite.country,
    COUNT(distinct tblDivingClub.number) as number_of_clubs,
    COUNT(distinct tblDiving.diving_number) as number_of_divings,
    COUNT(distinct tblDiving.guide) as number_of_guids,
    sum(tblDiving.number_of_divers) as number_of_divers
from tblCountry 
inner join tblSite 
    on tblCountry.name=tblSite.country
inner join tblDiving 
    on tblSite.name = tblDiving.diving_site
inner join tblDivingClub 
    on tblDiving.diving_club = tblDivingClub.number
where tblSite.name in (
         select tblSite.name 
         from tblSite 
         where tblSite.country = 'New York' 
     ) 
     and tblDiving.date_of_diving >= DATEADD(year,-1, GETDATE())
group by tblSite.name,tblSite.site_length,tblSite.site_depth,
    tblSite.water_type,tblSite.country

我想展示其中潜水量最多的月份（'tblDiving.date_of_diving'）和本月的分配数量。

有可能吗？

Answer 1

唉，这真是一个不同的问题。您的上述查询总结了多个月。并且count(distinct)不是累积的。所以，你每个月可以有一个人参与。该月的计数为1.对于这一年，它可以是1到12之间的任何数字，具体取决于同一个人是否在多个月内潜水。

所以，你可以做你想做的事情：

select t.*
from (select tblSite.name, tblSite.site_length, tblSite.site_depth, tblSite.water_type,   
             tblSite.country,
             COUNT(distinct tblDivingClub.number) as number_of_clubs,
             COUNT(distinct tblDiving.diving_number) as number_of_divings,
             COUNT(distinct tblDiving.guide) as number_of_guids,
             sum(tblDiving.number_of_divers) as number_of_divers,
             year(tblDiving.date_of_diving) as yr, month(tblDiving.date_of_diving) as mon,
             row_number() over (partition by tblSite.name, tblSite.site_length, tblSite.site_depth, tblSite.water_type, tblSite.country
                                order by COUNT(distinct tblDiving.diving_number)
                               ) as seqnum
      from tblCountry inner join
           tblSite
           on tblCountry.name = tblSite.country inner join
           tblDiving
           on tblSite.name = tblDiving.diving_site inner join
           tblDivingClub
         on tblDiving.diving_club = tblDivingClub.number
      where tblSite.name in (select tblSite.name from tblSite where tblSite.country = 'New York' ) and
            tblDiving.date_of_diving >= DATEADD(year, -1, GETDATE())
      group by tblSite.name, tblSite.site_length, tblSite.site_depth,
               tblSite.water_type, tblSite.country,
               year(tblDiving.date_of_diving), month(tblDiving.date_of_diving)
     ) t
where seqnum = 1;

要按年获取数据摘要，您需要将其加回原始查询。

Answer 2

不确定

...
group by month(tblDiving.date_of_diving), ...

只要它只有1年的学期就会工作。如果这个报告跨越几年，你将不得不按年（），月（）等分组。或者，如果你使用MSSQL 2012+，那么就有一个EOMONTH（）函数。

是否可以按月计算？

2 个答案: