我需要一些帮助，每个区域的所有projectTypes每月获得项目计数。我已经尝试了以下声明，但它没有返回我需要的内容。 下面的语句的问题是它只在那个月有计数时才返回projectType。如果月份没有计数，我需要返回零。 非常感谢任何帮助。
SELECT r.region, pt.projectType, count(p.id) as totalCount, p.postedOn as monthCount
FROM region r cross join ProjectTypes pt left join projects p on p.regionID = r.id and pt.id = p.TypeID
WHERE year(p.postedOn) = '2012'
group by r.region, pt.projectType, p.postedOn
order by r.region
请在此处提供示例：http://sqlfiddle.com/#!3/6680f/18
regions: ------------------------- id | region | ------------------------- 1 | East | ------------------------- 2 | MidWest | ------------------------- 3 | West | ------------------------- Project Type: ------------------------- id | projectType | ------------------------- 1 | Web Desgin | ------------------------- 2 | Database | ------------------------- 3 | Development | ------------------------- Projects: ------------------------------------------------------------------------- id | projectName | regionID | projectTypeID | postedOn | ------------------------------------------------------------------------- 1 | Project 1 | 1 | 2 | 2012-09-02 | ------------------------------------------------------------------------- 2 | Project 2 | 2 | 2 | 2012-09-02 | ------------------------------------------------------------------------- 3 | Project 3 | 1 | 1 | 2012-09-02 | ------------------------------------------------------------------------- 4 | Project 4 | 3 | 2 | 2012-09-02 | ------------------------------------------------------------------------- 5 | Project 5 | 3 | 1 | 2012-10-02 | ------------------------------------------------------------------------- 6 | Project 6 | 3 | 2 | 2012-10-02 | ------------------------------------------------------------------------- 7 | Project 7 | 3 | 3 | 2012-10-02 | ------------------------------------------------------------------------- 8 | Project 8 | 2 | 3 | 2012-10-02 | ------------------------------------------------------------------------- 9 | Project 9 | 1 | 2 | 2012-10-02 | ------------------------------------------------------------------------- 10 | Project 10 | 1 | 2 | 2012-10-02 | ------------------------------------------------------------------------- Desired Results: --------------------------------------------------------- Region | project Type | totalCount | monthCount | --------------------------------------------------------- East | Web Desgin | 1 | September | --------------------------------------------------------- East | Database | 1 | September | --------------------------------------------------------- East | Development | 0 | September | --------------------------------------------------------- Midwest | Web Desgin | 0 | September | --------------------------------------------------------- Midwest | Database | 1 | September | --------------------------------------------------------- Midwest | Development | 0 | September | --------------------------------------------------------- West | Web Desgin | 0 | September | --------------------------------------------------------- West | Database | 1 | September | --------------------------------------------------------- West | Development | 0 | September | --------------------------------------------------------- East | Web Desgin | 0 | October | --------------------------------------------------------- East | Database | 2 | October | --------------------------------------------------------- East | Development | 0 | October | --------------------------------------------------------- Midwest | Web Desgin | 0 | October | --------------------------------------------------------- Midwest | Database | 0 | October | --------------------------------------------------------- Midwest | Development | 1 | October | --------------------------------------------------------- West | Web Desgin | 1 | October | --------------------------------------------------------- West | Database | 1 | October | --------------------------------------------------------- West | Development | 1 | October | ---------------------------------------------------------
答案 0 :(得分：1)
WITH块定义了一个需要几个月（或者更确切地说，每个月的第一天）的虚拟表。这扩展了您的CROSS JOIN，为您提供所有月份。
;WITH months(startdate) AS (
SELECT CAST('20120901' AS date)
UNION ALL
SELECT dateadd(m,1,startdate)
FROM months
WHERE startdate < '20121001'
)
SELECT r.region,
pt.projectType,
count(p.id) totalCount,
DATENAME(Month,m.startdate) monthCount
FROM region r
CROSS JOIN ProjectTypes pt
CROSS JOIN months m
LEFT JOIN projects p ON p.regionID = r.id
AND pt.id = p.TypeID
AND p.postedOn >= m.startdate
AND p.postedOn < dateadd(m,1,m.startdate)
GROUP BY r.region, pt.projectType, m.startdate
ORDER BY m.startdate, region, projecttype
OPTION (maxrecursion 0);
我将此应用于your fiddle
对于SQL Server 2000，或者为了提高性能，请将表Months创建为正确的表，并将其填入1999年至2169年的月份，例如
CREATE TABLE Months (
startdate datetime -- the first day of month
primary key
);
insert Months
select DateAdd(M,Number,'19990101')
from master..spt_values
where type='P'
GO
然后，只需使用条件对月份表选择您需要的月份范围，即如下：
SELECT r.region,
pt.projectType,
count(p.id) totalCount,
DATENAME(Month,m.startdate) monthCount
FROM region r
CROSS JOIN ProjectTypes pt
JOIN months m on m.startdate between '20120901' and '20121001'
LEFT JOIN projects p ON p.regionID = r.id
AND pt.id = p.TypeID
AND p.postedOn >= m.startdate
AND p.postedOn < dateadd(m,1,m.startdate)
GROUP BY r.region, pt.projectType, m.startdate
ORDER BY m.startdate, region, projecttype;
更新了SQL Fiddle
答案 1 :(得分：1)
您好我的回答是您表中的所有月份并制作套装。
SELECT
r.region
,pt.projectType
,(SELECT Count(*)
FROM Projects pp
WHERE pt.id = pp.TypeID
AND r.id = pp.regionID
AND DATENAME(MONTH, p.postedOn)=DATENAME(MONTH, pp.postedOn)) AS COUNT
,DATENAME(MONTH, p.postedOn) AS monthName
FROM ProjectTypes pt, region r,
(SELECT DISTINCT postedOn FROM Projects )p
ORDER BY r.region, DATENAME(MONTH, p.postedOn)