name a military unit whose command structure is 12th mechanized infantry division and garrison is alexandroupoli ?
SELECT DISTINCT var_uri where brack_open var_uri dbo_commandStructure dbr_12th_Mechanized_Infantry_Division_ attr_open Greece attr_close sep_dot var_uri dbo_garrison dbr_Alexandroupoli sep_dot var_uri a dbo_MilitaryUnit brack_close