数据库最大值解决方案
数据库最大值
SQLstr = "select dtime, MAX(h1) as 最大值, MIN(h1) as 最小值, AVG(h1) as 平均值 from realData rl1 where DATEPART('yyyy',dtime) in (select DATEPART('yyyy',dtime) as 年 from realData rl2 where DATEPART('yyyy',dtime) between 2013 and 2015 group by DATEPART('yyyy',dtime))";
总是提示"试图执行的查询中不包含作为合计函数一部分的特定表达式 'dtime'"
数据库access ,表如下图
------解决思路----------------------
本帖最后由 zhengytime 于 2015-05-25 11:00:10 编辑
在数据库中找出2013年到2015年每一年中H1字段的最大值最小值,SQLstr = "select dtime, MAX(h1) as 最大值, MIN(h1) as 最小值, AVG(h1) as 平均值 from realData rl1 where DATEPART('yyyy',dtime) in (select DATEPART('yyyy',dtime) as 年 from realData rl2 where DATEPART('yyyy',dtime) between 2013 and 2015 group by DATEPART('yyyy',dtime))";
总是提示"试图执行的查询中不包含作为合计函数一部分的特定表达式 'dtime'"
数据库access ,表如下图
------解决思路----------------------
select DATEPART(yyyy,dtime) as dtime, MAX(h1) as 最大值, MIN(h1) as 最小值, AVG(h1) as 平均值
from realData group by DATEPART(yyyy,dtime)
having DATEPART(yyyy,dtime)>= '2013' and DATEPART(yyyy,dtime) <= '2015'