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);

下面的例子在oracle中工作得很好

select to_char(columnname, 'DD/MON/yyyy'), count(*) from table_name group by to_char(createddate, 'DD/MON/yyyy');

下面是我使用的一个例子，当我需要计算特定日期的记录数量而不包括时间部分时:

select count(convert(CHAR(10), dtcreatedate, 103) ),convert(char(10), dtcreatedate, 103)
FROM dbo.tbltobecounted
GROUP BY CONVERT(CHAR(10),dtcreatedate,103)
ORDER BY CONVERT(CHAR(10),dtcreatedate,103)

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)

将值转换为组的日期类型。

GROUP BY CAST(myDateTime AS DATE)