You have a flat array that looks like this?

@GrpIDs = ( 'GrpID', '123', 'GrpID', '456' );
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Or is there some other data structure? It doesn't make sense to have 50% of the elements in the @GrpIDs array containing the text "GrpID". And without a better understanding of what your @GrpIDs data structure looks like, it's hard to give a good answer.

As for your query string, it can be parsed into a list of fields using Text::CSV. At that point, comparison of two arrays (assuming that's what you've got) is a matter of programming.