How To detect an obsolete Product Classification code

Summary:

How to detect which classification codes have been updated/changed when a new version of data is downloaded via descartes. Does a new code automatically get assigned to an item if the old code has been removed?

Content (required):

Running a data query does give the list of items which do not have the codes associated with the latest version, is there any alternative way to deal with it or we have to modify the condition after ever new version to detect the new codes.

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Code Snippet (add any code snippets that support your topic, if applicable):