Sharepoint Designer: 1. Save the date in a variable. (Build Dynamic String) 2. Check if the variable is empty. (Compare any datasource -> Value = Workflow Data ...)
http://office.microsoft.com/en-us/excel-help/compare-cell-contents-HP003056130.aspx#BMcompare_one_value_to_a_list_of_values =OR(EXACT(B2, A2:A4)) also works with AND