Еще один «трудный» путь:
DECLARE @table TABLE (id int, t0 int, t1 int, t2 int)
INSERT INTO @table(id, t0, t1, t2) VALUES(1, 4, 5, 6)
INSERT INTO @table(id, t0, t1, t2) VALUES(2, 3, 3, 2)
INSERT INTO @table(id, t0, t1, t2) VALUES(3, 6, 4, 5)
INSERT INTO @table(id, t0, t1, t2) VALUES(4, 4, 5, 5)
SELECT *
FROM @table
WHERE (t0+t1+t2) = 15
AND t0 BETWEEN 4 AND 6
AND t1 BETWEEN 4 AND 6
AND t2 BETWEEN 4 AND 6
AND t0 <> t1