sql 统计pv时加衰减因子

select query ,sum(decay_pv) sum_pv from
(
    select query, pv*EXP(0.02*int(datediff(day,'${date_str}'))) as decay_pv 
    from 你的数据表
    where  day between date_sub('${date_str}',7) and '${date_str}' 
)t
group by query 
order by sum_pv  desc
limit 200;