Question

我需要在多年内创建每周平均数。例如，如果我有：

select w.weekno, isNULL(AVG(quantity),0) as 'mcount'
from weeks w
left join sampledates sd ON w.weekNo = datepart(wk,sd.sampledate)
inner join sampledate_species_location ssdl ON sd.sampledateid = ssdl.sampledateid
inner join locations l ON ssdl.locationid = l.locationid 
inner join species s ON ssdl.speciesid = s.speciesid 
where year(sd.sampledate) = datepart(yy,getDate())
and l.locationid = 8 
and l.generalarea = 'Western'
group by w.weekno
order by w.weekno

我的结果需要的是：

WEEK     MCOUNT
17       0
18       6
19       7
20       8
21       9
22       5
23       0
24       8

我创建了一个名为周的表，周数为17-41周，因为这周没有希望将其加入结果将包括我没有数量的周数，但这不起作用。我也必须做同样的查询，但对于前几年，我不确定我将按照相同的格式按星期平均多年。

Answer 1

问题在于您的where子句和inner join。您需要为所有表继续left outer join s。然后，where条件必须在on子句中（否则left joins会变为inner join s）：

select w.weekno, isNULL(AVG(quantity),0) as 'mcount'
from weeks w left join
     sampledates sd
     ON w.weekNo = datepart(wk, sd.sampledate) and
        year(sd.sampledate) = datepart(yy, getDate()) left join
     sampledate_species_location ssdl
     ON sd.sampledateid = ssdl.sampledateid left join
     locations l
     ON ssdl.locationid = l.locationid and
        l.locationid = 8 and
        l.generalarea = 'Western' left join
     species s
     ON ssdl.speciesid = s.speciesid 
group by w.weekno
order by w.weekno;

TSQL创建多年的平均数周

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