Event Management System
I think you want a lookup table that shows the requirements for a particular event. In this case, generally I would also have attr1-3 in a separate table called 'Attribute' and a user_attribute table to assign attributes to a particular user_detail record. Then, you could assign a particular event to require n attributes through the lookup table- 

event_attribute (event_attribute_id [PK], event_id [FK], attribute_id [FK],...).