t1 - f1,f2,f3
t2 - f1,f4,f5
t3 - f4,f6,f7,f8
t4 - f8,f9

SELECT COUNT(*)
FROM t1
JOIN t2 ON t1.f1 = t2.f1
JOIN t3 ON t2.f4 = t3.f4
JOIN t4 ON t3.f8 = t4.f8