MS SQL-如何使用XML节点（字段中包含的XML）连接到表

我有一些返回一组记录的SQL代码，包括一个交叉应用程序，它从一个联接表中分离XML并查询XML。这很好，但是我需要查看基表中的记录，即使XML中没有匹配项

例如，以下代码可以工作，但仅当XML中的WHERE子句与下面的WHERE子句匹配时才会显示记录（眼科检查、HgA1c和PCDate>3/1/2014）

我需要的是显示我的遭遇\u ExamDetails/EcounterInfoView数据，即使没有XML匹配。通常，当这些只是表时，我使用联接（如下面的左联接）：

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您将希望使用外部应用程序而不是交叉应用程序

这应该可以做到：

 select 
  EncounterInfoView.AppointmentDate,
  pref2.value('(PCare/text())[1]', 'varchar(50)') as PCARE,
  TRY_PARSE(pref2.value('(PCDate/text())[1]', 'varchar(50)') AS date) as PCDate,
  pref2.value('(PCareComm/text())[1]', 'varchar(50)') as PCareComm

from
  Encounter_ExamDetails 
  left join dbo.Encounter_PhysicalExam on dbo.Encounter_PhysicalExam.FormID = dbo.Encounter_ExamDetails.FormID
  left join EncounterInfoView on EncounterInfoView.EncounterID = dbo.Encounter_PhysicalExam.EncounterID
  left join [dbo].[Encounter_History] on   [dbo].[Encounter_History].EncounterID = dbo.Encounter_PhysicalExam.EncounterID

OUTER APPLY
    HIST_PCARE.nodes('/PCareH/PCareList/PCareItem') AS PCARE(pref2)

WHERE
  (EncounterInfoView.AppointmentDate BETWEEN ('2014-03-01') and ('2014-04-01'))
    and
       (
            (pref2.value('(PCare/text())[1]', 'varchar(50)') = 'Eye Exam'
            or  pref2.value('(PCare/text())[1]', 'varchar(50)') = 'HgA1c'
            or pref2.value('(PCare/text())[1]', 'varchar(50)') IS NULL)
            and (TRY_PARSE(pref2.value('(PCDate/text())[1]', 'varchar(50)') AS date) >= '2014-03-01'
            or TRY_PARSE(pref2.value('(PCDate/text())[1]', 'varchar(50)') AS date) is null)
        )

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看起来这很有帮助，因为我现在得到的是空值记录。但是，当我的try_parse date>3/1时，它仍然在删除记录。我相信这是因为这是在where子句中，所以它减少了选择。这就像我需要一种“外部应用”的方法，其中where子句只在该外部应用上，而不是在整个选择上。我已经更新了我的答案，我相信您现在应该会得到一些结果。TRY_解析可能返回null，这导致结果被排除。尝试一下，让我知道它是否适合你。这会增加一些记录，但只是一些。我认为问题是，is null将发现记录的存在，但值为null。我实际上需要它做的是，即使pref2 XML（PCare/PCDate）中没有记录，也要从基表返回记录（Conference_ExamDetails）。我最终使用临时表，拉入XML，然后从基表中选择记录并连接到临时表。

 select 
  EncounterInfoView.AppointmentDate,
  pref2.value('(PCare/text())[1]', 'varchar(50)') as PCARE,
  TRY_PARSE(pref2.value('(PCDate/text())[1]', 'varchar(50)') AS date) as PCDate,
  pref2.value('(PCareComm/text())[1]', 'varchar(50)') as PCareComm

from
  Encounter_ExamDetails 
  left join dbo.Encounter_PhysicalExam on dbo.Encounter_PhysicalExam.FormID = dbo.Encounter_ExamDetails.FormID
  left join EncounterInfoView on EncounterInfoView.EncounterID = dbo.Encounter_PhysicalExam.EncounterID
  left join [dbo].[Encounter_History] on   [dbo].[Encounter_History].EncounterID = dbo.Encounter_PhysicalExam.EncounterID

OUTER APPLY
    HIST_PCARE.nodes('/PCareH/PCareList/PCareItem') AS PCARE(pref2)

WHERE
  (EncounterInfoView.AppointmentDate BETWEEN ('2014-03-01') and ('2014-04-01'))
    and
       (
            (pref2.value('(PCare/text())[1]', 'varchar(50)') = 'Eye Exam'
            or  pref2.value('(PCare/text())[1]', 'varchar(50)') = 'HgA1c'
            or pref2.value('(PCare/text())[1]', 'varchar(50)') IS NULL)
            and (TRY_PARSE(pref2.value('(PCDate/text())[1]', 'varchar(50)') AS date) >= '2014-03-01'
            or TRY_PARSE(pref2.value('(PCDate/text())[1]', 'varchar(50)') AS date) is null)
        )