displaying expiry date when customer name is selected from dropdown

i have a dropdown which is displaying customer name,  and i want customer license expiry date shown in the label,  and no'of days remaining to expire in a label when that customer name is selected from dropdown list, how to do that
here is the table
Customer Expiry Date A 2014/02/12 B 2014/03/30 C 2014/12/10 D 2014/12/20 E 2014/12/ ...