PGSQL calculates 14-day moving average

select 
(lag(shou,1)  over(order by id)+
lag(shou,2)  over(order by id)+
lag(shou,3)  over(order by id)+
lag(shou,4)  over(order by id)+
lag(shou,5)  over(order by id)+
lag(shou,6)  over(order by id)+
lag(shou,7)  over(order by id)+
lag(shou,8)  over(order by id)+
lag(shou,9)  over(order by id)+
lag(shou,10)  over(order by id)+
lag(shou,11)  over(order by id)+
lag(shou,12)  over(order by id)+
lag(shou,13)  over(order by id)+
lag(shou,14)  over(order by id))/14,
* from bh