"from t" ^ r3 ^ ", t" ^ r2 ^ ", t" ^ r1 ^ " " ^
"where " ^ "t" ^ r1 ^ ".att0 = '" ^ (List.hd xres) ^ "' and t" ^ r1 ^
".att1 = t" ^ r2 ^ ".att0 and t" ^ r1 ^ ".att1 = t" ^ r3 ^
"from t" ^ r3 ^ ", t" ^ r2 ^ ", t" ^ r1 ^ " " ^
"where " ^ "t" ^ r1 ^ ".att0 = '" ^ (List.hd xres) ^ "' and t" ^ r1 ^
".att1 = t" ^ r2 ^ ".att0 and t" ^ r1 ^ ".att1 = t" ^ r3 ^