//按天統計,createtime爲數據庫的date類型，格式爲：yyyy-MM-dd hh24:mi:ss
select trunc(createtime,'DD') as 日期,count(主鍵) as 數量 from tablename
group by trunc(createtime, 'DD') order by trunc(createtime, 'DD')
e.g.
select trunc(bjsj,'DD') as 日期,count(jjdbh) as 數量 from t_jjd
where bjsj>=to_date('2017-05-01 00:00:00','yyyy-MM-dd hh24:mi:ss')
and bjsj<to_date('2017-06-01 00:00:00','yyyy-MM-dd hh24:mi:ss')
group by trunc(bjsj, 'DD') order by trunc(bjsj, 'DD')
//按自然周統計
select to_char(date,'iw'),sum() from tablename
group by to_char(date,'iw')
//按自然月統計
select to_char(date,'mm'),sum()
from tablename
group by to_char(date,'mm')
//按季統計
select to_char(date,'q'),sum()
from tablename
group by to_char(date,'q')
//按年統計
select to_char(date,'yyyy'),sum()
from tablename
group by to_char(date,'yyyy')
