比较年份，用substr截取前4位快，还是date('Y')快?

//substr

if(substr($startTime,0,4) == substr($endTime,0,4)){

    $str .= " L.year = ".substr($startTime,0,4);

    if(substr($startTime,4,2) == substr($endTime,4,2)){

        $str .= " and L.mOnth= ".substr($startTime,4,2);

        if(date('Ynd',strtotime($startTime)) == date('Ynd',strtotime($endTime))){

            $str .= " and day = ".date('d',strtotime($startTime));

        }else{

            $str .= " and log_date between '$startTime' and '$endTime' ";

        }

    }else{

        $str .= " and log_date between '$startTime' and '$endTime' ";

    }

}else{

    $str .= " L.log_date between $startTime and $endTime";

}



//date



 if(date('Y',strtotime($startTime)) == date('Y',strtotime($endTime))){

        $str = " where year = ".date('Y',strtotime($startTime));

        if(date('Yn',strtotime($startTime)) == date('Yn',strtotime($endTime))){

            $str .= " and mOnth= ".date('n',strtotime($startTime));

            if(date('Ynd',strtotime($startTime)) == date('Ynd',strtotime($endTime))){

                $str .= " and day = ".date('d',strtotime($startTime));

            }else{

                $str .= " and log_date between '$startTime' and '$endTime' ";

            }

        }else{

            $str .= " and log_date between '$startTime' and '$endTime' ";

        }

    }else{

        $str = " where log_date between '$startTime' and '$endTime' ";

    }