Question

我有一张桌子tbltrans

transno | agent name | date|

--------+-----------+-------

 1 01   | waw   |2014-10-10|

 1 02   | waw   |2014-10-15|

 1 03   | waw   |2014-10-20|

 1 04   | waw   |2014-10-30|

我想查询postgresql来计算agentname的平均时间

结果如下：

agent name | average time|

--------+------------

 waw      | 5days      |

我希望有人帮助我。。谢谢，更多的力量：）

Answer 1

这样的事情：

select agent_name, 
       (max(date) - min(date)) / count(*) as average_days
from tbltrans
group by agent_name;

Answer 2

这是解决方案：B - ）

with diff(agent_name, values) as 
(
 select agent_name, date - lag(date,1,date) over (partition by agent_name order by date) from agents
)
select agent_name, 
       case when count(values) = 1 then '0 days'
            else to_char(sum(values)::float / (count(values) - 1), '999.99') || ' days'
       end
from diff
group by agent_name;

我在解决方案中使用了Windowing functions和Common table expressions

postgresql查找2个或更多日期之间的平均时间

2 个答案: