SQL按每日查询

查询一段时间内，每天有多少注册量：select count(*) as count,RegDate from user where RegDate between "2014-01-01" and "2014-04-04" group by day(RegDate) order by RegDate;
查询结果count  RegDate 

3          2014-01-13 16:52:191          2014-03-03 15:00:411          2014-03-10 15:35:181          2014-03-20 17:00:051          2014-03-25 14:37:112          2014-03-26 17:42:15

//根据要求的日期来取数据    var sqlPeriod;    if(period == "day"){        sqlPeriod="day(RegDate),month(RegDate),year(RegDate)";    }else if(period == "month"){        sqlPeriod="month(RegDate),year(RegDate)";    }else if(period == "year"){        sqlPeriod="year(RegDate)";    }else if(period == "week"){        sqlPeriod="week(RegDate)";    }else if(period == "quarter"){        sqlPeriod="quarter(RegDate)";    }
“select count(*) as count,RegDate as regDate from user where RegDate between ? and ? group by "+sqlPeriod+" order by RegDate",[startDate,endDate]