在XML节点SQL Server查询中使用sql：variable的语法错误

Question

我一直在研究从SQL Server数据库中提取XML数据的查询。 我想从XML中提取一个特定的行。 如果我在.nodes行中对ID进行硬编码，它会按预期工作，但是当用sql：variable替换硬编码值并且耗尽我的Google-foo时，我无法通过语法错误

'''SQL
DECLARE @XML XML = '<DynamicModel>
<AvailableElements>
  <Control Id="97a0d1c6-f2b4-4f6f-8d01-f6110f1679af">
  <Property Name="Name" Value="Picklist1" />
  <Property Name="Id" Value="97a0d1c6-f2b4-4f6f-8d01-f6110f1679af" />
  <Property Name="Label" Value="Label value here" />
  <Property Name="SelectedItemId" Value="Value in here" Type="System.Nullable`1[[System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089]], mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" IsRequired="True" IsReference="True" />
  <Elements />
  <AvailableElements />
</Control>
</AvailableElements>
</DynamicModel>'
DECLARE @ElementID NVARCHAR(100) = '97a0d1c6-f2b4-4f6f-8d01-f6110f1679af'

/* WORKS */
SELECT
codedValue.value('@Name[1]', 'nvarchar(500)') AS ItemName,
codedValue.value('@Value[1]', 'nvarchar(500)') AS ItemValue
FROM @XML.nodes('/DynamicModel/AvailableElements/Control[@Id="97a0d1c6-f2b4-4f6f-8d01-f6110f1679af"]/Property') AS x(codedValue)
WHERE codedValue.value('@Name[1]', 'nvarchar(500)') IN ('Text','Date','SelectedItemId','Label')

/* DOES NOT WORK */
SELECT
codedValue.value('@Name[1]', 'nvarchar(500)') AS ItemName,
codedValue.value('@Value[1]', 'nvarchar(500)') AS ItemValue
FROM    @XML.nodes('/DynamicModel/AvailableElements/Control[@Id="sql:variable("@ElementID")]/Property') AS x(codedValue)
WHERE codedValue.value('@Name[1]', 'nvarchar(500)') IN ('Text','Date','SelectedItemId','Label')
'''

硬编码版本返回两行，这些行基于XML是正确的。 使用sql：变量的版本错误消息'XQuery [nodes（）]：'@'附近的语法错误，期望']'。'

Answer 1

您的查询应该像这样 -

SELECT
codedValue.value('@Name[1]', 'nvarchar(500)') AS ItemName,
codedValue.value('@Value[1]', 'nvarchar(500)') AS ItemValue
FROM    @XML.nodes('/DynamicModel/AvailableElements/Control[@Id=sql:variable("@ElementID")]/Property') AS x(codedValue)
WHERE codedValue.value('@Name[1]', 'nvarchar(500)') IN ('Text','Date','SelectedItemId','Label')