select  distinct (s.C)
  from  TTTT as t, TTTT as s    
 where  something
        and s.A = t.A 
        and s.B = t.B;

##</code><code>##

select  distinct (s.C)
  from  TTTT.t, TTTT.s          
 where  something
        and s.A = t.A 
        and s.B = t.B;