oracle知识（关于时间格式和left jion on and）

三、oracle日期格式查询与转换

select count(al.actor),al.actdate from tbl_action_log al where al.action='LOGIN'
and al.actdate > to_date('2013-04-22 00:00','yyyy-mm-dd HH24:Mi')
and al.actdate < to_date('2013-04-29 00:00','yyyy-mm-dd HH24:Mi')
group by al.actdate

select to_char(al.actdate,'yyyy/mm/dd HH24:mi:ss') from tbl_action_log al;

四、对日期格式进行分组，因为返回字段为varchar类型,所以分组时应该也为to_char进行转换
select count(*),to_char(al.actdate,'yyyy-mm-dd') "day" from tbl_action_log al where al.action='LOGIN'
and al.actdate >= to_date('2013-04-22','yyyy-mm-dd')
and al.actdate < to_date('2013-04-29','yyyy-mm-dd')
group by to_char(al.actdate,'yyyy-mm-dd')
order by to_char(al.actdate,'yyyy-mm-dd')

五、inner join  on 后添加过滤条件，可以通过and关键字进行添加
select count(*)
from tbl_model_draft t
inner join tbl_model m on t.modelid = m.modelid
and m.isdelete=0