1.背景
数据库表名为tablename。其中两个字段为startdate(开始时间)，closedate(结束时间)。
2.需求
建立试图，查询出间隔时间并显示为自定义的格式。
3.sql语句
select t.*, round(to_number(t.closedate-t.startdate)*24*60*60)||'秒' "在线时长（秒）",
(
decode((trunc(to_number(t.closedate-t.startdate)*24)),null,null,0,null,trunc(to_number(t.closedate-t.startdate)*24)||'时')
||
decode((trunc(mod((to_number(t.closedate-t.startdate)*24*60),60))),null,null,0,null,trunc(mod((to_number(t.closedate-t.startdate)*24*60),60))||'分')
||
decode((trunc(mod((to_number(t.closedate-t.startdate)*24*60*60),60))),null,'无',trunc(mod((to_number(t.closedate-t.startdate)*24*60*60),60))||'秒')) "登录时长（显示为 **时**分**秒 的形式）",
(select count(*) from tablename b where b.userbiscode=t.userbiscode and to_char(b.startdate,'yyyy-mm-dd')=to_char(sysdate,'yyyy-mm-dd')) "今日登录次数",
(select closedate from
(select a.closedate,rownum as rn from
(select closedate from tablename where to_char(startdate,'yyyy-mm-dd')=to_char(sysdate,'yyyy-mm-dd') order by startdate desc) a)
where rn<2) "最后登录时间"
from tablename t
WHERE to_char(t.startdate,'yyyy-mm-dd')=to_char(sysdate,'yyyy-mm-dd') order by t.startdate desc;