MySQL FROM_UNIXTIME效率 VS PHP date()效率 数…

CREATE TABLE `t1` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `remark` char(10) DEFAULT NULL,
  `add_time` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=458731 DEFAULT CHARSET=latin1;

INSERT INTO t1(remark,add_time) SELECT remark,add_time FROM t1

// 获取开始时间的微妙
$startTime = microtime(true);
$pdo = new PDO("mysql:host=localhost;dbname=test","root","");
$rs = $pdo -> query("select id,add_time,remark from t1 limit 262144");
$data = $rs->fetchAll();

$php_number_count = 0;
foreach ($data as $item){
    $php_number_count +=1;
    $tmp[] = date("Y-m-d", $item['add_time']);
}

echo $php_number_count."<br>";
echo "开始时间:".$startTime."<br>";
echo "结束时间:".$endTime = microtime(true). "<br>";
$resTime = $endTime - $startTime;
echo "用时:".$resTime;exit;

262144
开始时间:1481871208.7704
结束时间:1481871210.1535
用时:1.3830921649933 秒

// 获取开始时间的微妙
$startTime = microtime(true);
$pdo = new PDO("mysql:host=localhost;dbname=test","root","");
$rs = $pdo -> query("select id,remark,add_time,FROM_UNIXTIME(add_time, '%Y-%m-%d') as datetime from t1 limit 262144");
$data = $rs->fetchAll();

echo "开始时间:".$startTime."<br>";
echo "结束时间:".$endTime = microtime(true). "<br>";
$resTime = $endTime - $startTime;
echo "用时:".$resTime;exit;

开始时间:1481871495.7308
结束时间:1481871496.7279
用时:0.99707913398743

// ..........
$data = $rs->fetchAll();
foreach ($data as $row){
    $tmp[] = $row['add_time'];
};
// .........

开始时间:1481871764.8102
结束时间:1481871766.0483
用时:1.2380890846252