Oracle 經常使用語法

1、case when語句的使用

 實例：查詢數據，將地址編碼顯示爲具體地點

select m.*,
case 
m.caddr_code
when 1 then '住處'
when 2 then '交通地點'
when 3 then '工做地點'
when 4 then '運動休閒'
else
'其餘'
end as caddr_code
from Vav_Radio_Sec_Action_Mem m where 1=1 

2、 group by分組函數

實例：分組查詢20160901至20161031日的數據總數

select dw.cdate,count(*) from vav_radio_family_mem_weight dw
where dw.cdate>=to_date('20160901','yyyymmdd')
and dw.cdate<=to_date('20161031','yyyymmdd')
and dw.cnetworkid=4205
group by dw.cdate
order by dw.cdate

3、to_date ()

實例：查詢2016/11/22 2:00:00 至2016/11/23 2:00:00之間的不重複的樣本編號

select distinct cfamilyid from vav_radio_sec_action_mem 
where cstart_time>to_date('2016/11/22','yyyy/mm/dd')+2/24
and cstart_time<to_date('2016/11/22','yyyy/mm/dd')+1+2/24 and  cregion_id=4205

   to_date('2016/11/22','yyyy/mm/dd')+2/24表示2016/11/22增長兩小時/24小時制

  to_date('2016/11/22','yyyy/mm/dd')+1+2/24 表示2016/11/22增長一天和兩小時/24小時制