[support] Views filter against another field.

Hi, Does anyone know how to filter a view by comparing the value of two fields?? Longer description - I have a content type that has 3 date fields.. I want a view that shows all the content where the values in date_field_1 are different from the values in date_field_2.. I can only seem to filter based on set static vales or with date fields using strtotime expressions.. I can't see any way to do a comparison of two fields.. Thanks..