需要多个子查询，分别返回每个记录中的所有记录

Question

我需要构建一份报告以显示每个员工（主要查询）以及每个测试的日期和/或结果，并为每个测试列分别显示一列测试。我想我的查询的结果是这样的：

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SQL我现在有，与子查询在我FROM语句，在TB日期/结果拉和XRayDate，但结果乘以一次我为XRayDate添加第二个子查询，给我21结果，而不是总共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 

下面是使用SQL上述结果的一个样本：

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 

我新，以在SQL Developer中的子查询，让您的建议/反馈是受欢迎的。

Answer 1

Row_number测试和完全加入rn。十字/外应用的结果，这样的

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 

Answer 2

可以显著通过简化查询：

• 不走样表与他们已经拥有（在评论上述由Sean Lange提到）的同名。例如，说明FROM EMPLOYEE EMPLOYEE没有意义，因为您可以参考标识为EMPLOYEE的EMPLOYEE表。相反，请尝试使用简写标识符来使查询更快，更易于阅读。
• 在JOIN不是使用子查询，除非你真的需要

因此，例如：

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' 

应该给你同样的结果在你的查询有问题。现在

，如果你当JOIN s的包括比你没有他们返回的记录数量更多，这表明有两种：

• 在TUBER表的多个记录的每个值FLDEMPLOYEE
• PHYSLOG表中的多个记录每个值为FLDEMPLOYEE
• 或两者都有！

您可以通过从这些表返回更多的详细检查此：

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' 

我建议你选择一些相关的领域，而不是实际使用t.*和x.*，但我不知道你的表结构，因为你没有提供它。

如果您发现FLDEMPLOYEE的每个值的JOIN ed表中有多个记录，那么您需要决定如何处理此问题，最有可能的方法是对数据进一步过滤在WHERE子句中，或者通过使用GROUP BY子句。例如，如果您意识到TUBER表中有多个记录，每个值为FLDEMPLOYEE，则可能会看到您可以过滤到仅使用TUBER表中某些其他字段感兴趣的记录：

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' 

只要你确定你申请任何额外的过滤从TUBER表每FLDEMPLOYEE值（总是会）将只返回一个记录，这应该能正常运行。

另外，例如，如果你认识到，有在PHYSLOG表的FLDEMPLOYEE每个值的多个记录，您可能希望只与最近的日期在FLDDATE返回字段的记录：

SELECT e.FLDLNAME, 
     e.FLDFNAME, 
     e.FLDREC_NUM, 
     t.FLDDATE AS [TUBER Date], 
     t.FLDCLASS AS [TUBER Result], 
     MAX(x.FLDDATE) AS [Most Recent 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' 
GROUP BY e.FLDLNAME, 
     e.FLDFNAME, 
     e.FLDREC_NUM, 
     t.FLDDATE, 
     t.FLDCLASS