在Sql 2008之前，通过去掉日期部分:

GROUP BY CONVERT(CHAR(8),DateTimeColumn,10)

GROUP BY DATEADD(day, DATEDIFF(day, 0, MyDateTimeColumn), 0)

或者在SQL Server 2008以后，你可以像@Oded建议的那样简单地转换为Date:

GROUP BY CAST(orderDate AS DATE)

将值转换为组的日期类型。

GROUP BY CAST(myDateTime AS DATE)

GROUP BY DATE(date_time_column)

在Sql 2008之前，通过去掉日期部分:

GROUP BY CONVERT(CHAR(8),DateTimeColumn,10)

CAST datetime字段到日期

select  CAST(datetime_field as DATE), count(*) as count from table group by CAST(datetime_field as DATE);