好吧,我不像我应该那样精通SQL,但我很熟悉连接,联盟等等是如何工作的,而且我不能提出解决方案为了这。我试图从两个不同的表中获取数据,但是猴子扳手是在我的结果集中右侧表格可能比我实际需要的行数多。我必须加入这两张表的唯一标准是电子邮件地址。代码如下:在两个SQL表之间连接数据
CREATE TABLE #PPEInfo(StudentEmail nvarchar(128), StudentName nvarchar(128), DevUnits int)
INSERT INTO #PPEInfo (StudentEmail, DevUnits)
SELECT e.StudentEmail AS Email, sum(ck.DevelopmentUnits) AS DevUnits
FROM Enrollments e, CourseKeys ck
WHERE e.CertGenerated = 'true'
AND e.CourseId = ck.CourseId
GROUP BY e.StudentEmail
ORDER BY DevUnits DESC
SELECT p.StudentEmail, p.DevUnits, s.StudentName
FROM #PPEInfo p
RIGHT OUTER JOIN Surveys s
ON p.StudentEmail = s.StudentEmail
ORDER BY DevUnits DESC, StudentName ASC
DROP TABLE #PPEInfo
问题是我收到多个学生姓名,因为他们在提交申请时可能没有使用过相同的姓名。例如:
Email Address James R. Salvati
Email Address James Salvati
,我已经想出唯一的办法是先填充我的临时表与电子邮件地址,然后查询表调查使用的名称“TOP(1)”只得到一个学生的名字。它确实有效,但它非常耗费CPU资源,而且我正在处理大量记录。下面的代码(虽然我不关心在这一点上只是想拿出东西DevUnits):
CREATE TABLE #PPEInfo(ID int IDENTITY(1,1), StudentEmail nvarchar(128), StudentName nvarchar(128), DevUnits int)
INSERT INTO #PPEInfo (StudentEmail)
SELECT DISTINCT StudentEmail FROM Enrollments
WHERE CertGenerated = 'true'
DECLARE @rowID int
DECLARE @email nvarchar(128)
SET @rowID = (SELECT max(ID) FROM #PPEInfo)
WHILE (@rowID > 0)
BEGIN
SET @email = (SELECT StudentEmail FROM #PPEInfo WHERE ID = @rowID)
UPDATE #PPEInfo
SET StudentName = (SELECT TOP(1) s.StudentName FROM Surveys s
WHERE s.StudentEmail = @email)
WHERE ID = @rowID
SET @rowID = @rowID - 1
END
SELECT * FROM #PPEInfo
ORDER BY DevUnits DESC
DROP TABLE #PPEInfo
我从来没有真正张贴在这些板之一。我通常会找到解决方案或者找出一个解决方案,但是这个解决方案超出了我的SQL实力。
谢谢!
您使用的是哪个版本的SQL Server? – 2013-03-07 00:53:35