get data in combobox

hi I have a database I want to get data from a field of database to the drpdwn menu or in a table but but for a exmple X 1 an 2 free 2 an 2 free 3 am 2 buy 4 nm 2 buy tax when I get data from database it loads two "free" value in dropdown menu so I want to get only one record for each but I cant do it