mysql按照日周月年聚合数据

//根据时间类型来组装时间条件
if ($time_type == 2){
    //周报表
    $group = "concat_ws('~',subdate(FROM_UNIXTIME(create_time,'%Y-%m-%d'),date_format(FROM_UNIXTIME(create_time),'%w')-1),subdate(FROM_UNIXTIME(create_time,'%Y-%m-%d'),date_format(FROM_UNIXTIME(create_time),'%w')-7))";
}else if($time_type == 3){
    //月报表
    $group = "FROM_UNIXTIME(create_time,'%Y-%m')";
}else if($time_type == 4){
    //年报表
    $group = "FROM_UNIXTIME(create_time,'%Y')";
}else{
    //日报表
    $group = "FROM_UNIXTIME(create_time,'%Y-%m-%d')";
}

$field = "COUNT(itemid) as total,SUM(pay_amount) as pay_amount,".$group." as date";

$sql = "select $field from mddweb_dy_order where $condition group by $group";