sql按小时分组

select isnull(sum(任意字段),0) as num,SUBSTRING(CONVERT(VARCHAR,时间字段,120), 12, 2) as ctime from 表 where DATEDIFF(dd, 时间字段, GETDATE())=0 GROUP BY SUBSTRING(CONVERT(VARCHAR,时间字段,120), 12, 2)

-- 查看当天的数据
select * from 表 where DATEDIFF(dd, 时间字段, GETDATE())=0

select IFNULL(sum(任意字段),0) as num,DATE_FORMAT(时间字段,'%d')  as hourtime,'0' as ctime from `库`.表 WHERE DATEDIFF(时间字段, now())=0   GROUP BY DATE_FORMAT(时间字段,'%d')
					

-- 查看当天的数据
select * from 表 where DATEDIFF(时间字段, now())=0