您可以计算行号，然后使用递归cte进行乘法。然后获取每个包含乘法最终结果的类的最大rnum（计算的row_number）值。
--Calculating row numberswith rownums as (select t1.*, (select count(*) from t t2 where t2.token<=t1.token and t1.class=t2.class) as rnum from t t1)--Getting the max rnum for each class,max_rownums as (select class,max(rnum) as max_rnum from rownums group by class)--Recursive cte starts here,cte(class,rnum,probPaired,running_mul) as (select class,rnum,probPaired,probPaired as running_mul from rownums where rnum=1 union all select t.class,t.rnum,t.probPaired,c.running_mul*t.probPaired from cte c join rownums t on t.class=c.class and t.rnum=c.rnum+1)--Final value selectionselect c.class,c.running_mul from cte cjoin max_rownums m on m.max_rnum=c.rnum and m.class=c.class
SQL Fiddle
