1 echo select * from t11,t12,t13 where t12.f1=t13.f8 and t13.f7=t11.f1;
2 select * from t11,t12,t13 where t12.f1=t13.f8 and t13.f7=t11.f1;
4 echo select * from t11,t12,t13 where t12.f1=t13.f8 or t13.f7=t11.f1;
5 select * from t11,t12,t13 where t12.f1=t13.f8 or t13.f7=t11.f1;