SQL Server 2017

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DECLARE @xml xml = '
<Container>
  <Collection>
    <ItemName>SomeItem</ItemName>
    <IsDeletable>true</IsDeletable>
    <IsPersisted>false</IsPersisted>
  </Collection>
  <Collection>
    <ItemName>AnotherItem</ItemName>
    <IsDeletable>true</IsDeletable>
    <IsPersisted>true</IsPersisted>
    <ExistsInDB>true</ExistsInDB>
  </Collection>
  <Collection>
    <ItemName>ItemFoo</ItemName>
    <IsDeletable>true</IsDeletable>
    <IsPersisted>true</IsPersisted>
    <ExistsInDB>true</ExistsInDB>
  </Collection>
  <Collection>
    <ItemName>BarBazItem</ItemName>
    <IsDeletable>true</IsDeletable>
    <IsPersisted>true</IsPersisted>
    <ExistsInDB>false</ExistsInDB>
  </Collection>
</Container>
'

;WITH XmlStuff AS (
    SELECT CAST(xmlShredded.colXmlItem.query('local-name(.)') AS nvarchar(4000)) as XmlNodeName,
        xmlShredded.colXmlItem.value('.', 'nvarchar(4000)') AS XmlNodeValue,
        xmlShredded.colXmlItem.value('(../ExistsInDB)[1]', 'nvarchar(4000)') AS ExistsInDB
    FROM @xml.nodes('/*/Collection/child::node()') as xmlShredded(colXmlItem) 
)
SELECT *
FROM XmlStuff 
WHERE ExistsInDB = 'true'

XmlNodeName	XmlNodeValue	ExistsInDB
ItemName	AnotherItem	true
IsDeletable	true	true
IsPersisted	true	true
ExistsInDB	true	true
ItemName	ItemFoo	true
IsDeletable	true	true
IsPersisted	true	true
ExistsInDB	true	true