Building a select query to isolate all nodes with a date greater than

Here is a snippet of XML:

<AssignmentHistory Version="210002" DateLastPurged="2020-12-11">      <W20190107>          <Teaching>            <Name Class="1">Brother 1</Name>            <Name Class="2">Brother 2</Name>            <Name Class="3">Brother 3</Name>          </Teaching>      </W20190107>      <W20190114>          <Teaching>            <Name Class="1">Brother 1</Name>            <Name Class="2">Brother 2</Name>            <Name Class="3">Brother 3</Name>          </Teaching>      </W20190114>  </AssignmentHistory>  

I realise that my use of WYYYYMMDD for the element name was not very clever. I designed the XML file when I was only learning XML / XSL and now see it not to be good.

The above is stripped down just to show what I need to show.

I know I can do a path query like this:

XmlDocument doc = new XmlDocument();  doc.Load("file.xml");  XmlNodeList nl = doc.SelectNodes("AssignmentHist/*/Teaching");  ...  

And it will return all of the Teaching elements in a XmlNodeList.

The XML file is sorted in descending date order and what I would like to do is use a query that will select all teaching nodes where the date is greater than a specified value. At the moment I have to:

• Iterate the complete list
• Get the name of the parent node (WYYYYMMDD)
• Strip the leading W
• Extract the YYYY, MM & DD components
• Build a DateTime object and compare the date of interest against xxxx.Date.

It would be nice if the single select query could put all of those out. But can it be done?

https://stackoverflow.com/questions/65568644/building-a-select-query-to-isolate-all-nodes-with-a-date-greater-than January 05, 2021 at 03:27AM