我如何按星期或月份彙總付款？

Question

我有這個表：

date  payment 
----  ------- 
1/1/2014 2000 
13/1/2014 1200 
2/3/2014 1900 
3/4/2014 1800 
....  .... 
....  .... 

我要計算每週支付：由

date  payment 
-----  ------ 
month1  sum(month1) 
month2  sum(month2) 
.....  ..... 

Answer 1

select extract(week from date) as week, 
     sum(payment) as payments 
from your_table 
group by week