sql 按自然周,月，季度，年统计

//按自然周统计 
select to_char(date,'iw'),sum() 
from 
where 
group by to_char(date,'iw') 

//按自然月统计 
select to_char(date,'mm'),sum() 
from 
where 
group by to_char(date,'mm') 

//按季统计 
select to_char(date,'q'),sum() 
from 
where 
group by to_char(date,'q') 

//按年统计 
select to_char(date,'yyyy'),sum() 
from 
where 
group by to_char(date,'yyyy')