我需要构建一个报告，向我展示每个员工（主要查询），以及每个测试的日期和/或结果，每个测试都有一个单独的列。我希望我的查询结果如下所示：
FName LName TB Date TB Result XrayDate
--------------------------------------------------
Bob Jones 10/1/2016 P 10/1/2016
9/1/2015 P 8/1/2015
9/15/2014 N 7/1/2014
8/3/2013 N
10/1/2012 Q
9/4/2011 P
8/16/2010 P
下面是我现在拥有的SQL，在我的FROM语句中使用子查询来提取TB日期/结果和XRayDate，但是一旦我为XRayDate添加第二个子查询，结果就会相乘，给出21个结果而不是共有7行数据。
EMPLOYEE.FLDLNAME,
EMPLOYEE.FLDFNAME,
EMPLOYEE.FLDREC_NUM,
TUBER.FLDDATE as "TUBER Date",
TUBER.FLDCLASS as "TUBER Result",
XRayDate.FLDDATE as "XRay Date"
FROM EMPLOYEE EMPLOYEE
LEFT OUTER JOIN
(SELECT TUBER.FLDDATE, TUBER.FLDCLASS, TUBER.FLDEMPLOYEE
FROM TUBER TUBER) TUBER
ON EMPLOYEE.FLDREC_NUM = TUBER.FLDEMPLOYEE
LEFT OUTER JOIN
(SELECT PHYSLOG.FLDDATE, PHYSLOG.FLDTYPE,PHYSLOG.FLDEMPLOYEE
FROM PHYSLOG PHYSLOG
WHERE PHYSLOG.FLDTYPE = 'CXR') XrayDate
ON EMPLOYEE.FLDREC_NUM = XrayDate.FLDEMPLOYEE `EMPLOYEE.FLDLNAME
以下是使用SQL Above：
的结果示例Fname LName TB Date TB Result Xray Date
---------------------------------------
Bob Jones 10/1/2016 P 10/1/2016
10/1/2016 P 8/1/2015
10/1/2016 P 7/1/2014
9/1/2015 P 10/1/2016
9/1/2015 P 8/1/2015
9/1/2015 P 7/1/2014
9/15/2015 N 10/1/2016
9/15/2015 N 8/1/2015
9/15/2015 N 7/1/2014
8/3/2013 N 10/1/2016
8/3/2013 N 8/1/2015
8/3/2013 N 7/1/2014
10/1/2012 Q 10/1/2016
10/1/2012 Q 8/1/2015
10/1/2012 Q 7/1/2014
9/4/2011 P 10/1/2016
9/4/2011 P 8/1/2015
9/4/2011 P 7/1/2014
8/16/2010 P 10/1/2016
8/16/2010 P 8/1/2015
8/16/2010 P 7/1/2014
我是SQL Developer中子查询的新手，所以欢迎您提出建议/反馈。
答案 0 :(得分：0)
Row_number测试和rn的完全连接。交叉/外部应用结果，如
SELECT
EMPLOYEE.FLDLNAME,
EMPLOYEE.FLDFNAME,
EMPLOYEE.FLDREC_NUM,
TUBER_FLDDATE as "TUBER Date",
TUBER_FLDCLASS as "TUBER Result",
XRayDate_FLDDATE as "XRay Date"
FROM EMPLOYEE EMPLOYEE
CROSS APPLY
(SELECT TUBER_FLDDATE = TUBER.FLDDATE,
TUBER_FLDCLASS = TUBER.FLDCLASS,
XrayDate_FLDDATE = XrayDate.FLDDATE
FROM (SELECT rn = row_number() over(order by TUBER.FLDDATE), TUBER.FLDDATE, TUBER.FLDCLASS
FROM TUBER
WHERE EMPLOYEE.FLDREC_NUM = TUBER.FLDEMPLOYEE) TUBER
FULL OUTER JOIN (SELECT rn = row_number() over(order by PHYSLOG.FLDDATE), PHYSLOG.FLDDATE
FROM PHYSLOG
WHERE PHYSLOG.FLDTYPE = 'CXR' AND EMPLOYEE.FLDREC_NUM = PHYSLOG.FLDEMPLOYEE) XrayDate
ON XrayDate.rn=TUBER.rn
) tests
答案 1 :(得分：0)
您可以通过以下方式显着简化查询：
FROM EMPLOYEE EMPLOYEE没有意义，因为您已经可以引用标识为EMPLOYEE的{{1}}表。而是尝试使用速记标识符来使查询更快地编写并更易于阅读。EMPLOYEE中使用子查询
例如：
JOIN应该为您提供与您问题中的查询相同的结果。
现在，如果您在包含SELECT e.FLDLNAME,
e.FLDFNAME,
e.FLDREC_NUM,
t.FLDDATE AS [TUBER Date],
t.FLDCLASS AS [TUBER Result],
x.FLDDATE AS [XRay Date]
FROM EMPLOYEE e
LEFT OUTER JOIN TUBER t ON e.FLDREC_NUM = t.FLDEMPLOYEE
LEFT OUTER JOIN PHYSLOG x ON e.FLDREC_NUM = x.FLDEMPLOYEE
WHERE x.FLDTYPE = 'CXR'
时返回的记录数量大于没有它们时返回的记录数量，则表明存在以下任一记录：
JOIN TUBER表中有多条记录
FLDEMPLOYEE PHYSLOG表中有多条记录
您可以通过从这些表中返回更多详细信息来检查这一点：
FLDEMPLOYEE我建议选择一些相关字段，而不是实际使用SELECT e.FLDLNAME,
e.FLDFNAME,
e.FLDREC_NUM,
t.*,
x.*
FROM EMPLOYEE e
LEFT OUTER JOIN TUBER t ON e.FLDREC_NUM = t.FLDEMPLOYEE
LEFT OUTER JOIN PHYSLOG x ON e.FLDREC_NUM = x.FLDEMPLOYEE
WHERE x.FLDTYPE = 'CXR'
和t.*，但我不知道您的表格结构，因为您没有提供它。
如果您发现某x.*个表中有JOIN个值的多个记录，则需要决定如何处理此问题，最有可能是进一步过滤FLDEMPLOYEE子句中的数据，或使用WHERE子句。
例如，如果您发现GROUP BY表中有TUBER的每个值都有多条记录，您可能会发现可以过滤到您感兴趣的记录FLDEMPLOYEE表中的其他字段：
TUBER只要你确定无论你应用什么额外的过滤只会从SELECT e.FLDLNAME,
e.FLDFNAME,
e.FLDREC_NUM,
t.FLDDATE AS [TUBER Date],
t.FLDCLASS AS [TUBER Result],
x.FLDDATE AS [XRay Date]
FROM EMPLOYEE e
LEFT OUTER JOIN TUBER t ON e.FLDREC_NUM = t.FLDEMPLOYEE
LEFT OUTER JOIN PHYSLOG x ON e.FLDREC_NUM = x.FLDEMPLOYEE
WHERE x.FLDTYPE = 'CXR'
AND t.OtherField = 'SomeValue'
表中每TUBER个值返回一个记录（并且总是会），这应该可以正常工作。
或者，例如，如果您发现FLDEMPLOYEE表中有PHYSLOG的每个值都有多条记录，您可能只希望返回FLDEMPLOYEE中最近日期的记录。 1}} field：
FLDDATE