PDO::FETCH_CLASS和PDO::FETCH_INTO之间的区别是什么

查看这个PHP PDO获取对象

以及下方的示例

<?php
$sql_server = "localhost";
$sql_db = "test";
$sql_user = "root";
$sql_pass = "";
$pdo = new PDO("mysql:host=$sql_server;dbname=$sql_db", $sql_user, $sql_pass);
$sql = 'SELECT firstName, lastName FROM users';
$stmtA = $pdo->query($sql);
$stmtA->setFetchMode(PDO::FETCH_CLASS, 'Person');
$objA = $stmtA->fetch();
var_dump($objA);
//first create the object we will fetch into
$objC = new Person;
$objC->firstName = "firstName";
$objC->lastName = "lastName";
$stmtC = $pdo->query($sql);
$stmtC->setFetchMode(PDO::FETCH_INTO, $objC);
$objC = $stmtC->fetch(); // here objC will be updated
var_dump($objC);

class Person{
    public $firstName;
    public $lastName;
}

PDO:：FETCH_CLASS：返回指定类的实例，将每行的列映射到类中的命名属性。

<?php
class fruit 
{
    public $name;
    public $colour;
}
$sth = $dbh->prepare("SELECT name, colour FROM fruit");
$sth->execute();
$result = $sth->fetchAll(PDO::FETCH_CLASS, "fruit");
var_dump($result);
?>

上面的例子将输出类似于：

array(3) {
  [0]=>
  object(fruit)#1 (2) {
    ["name"]=>
    string(5) "apple"
    ["colour"]=>
    string(5) "green"
  }
  [1]=>
  object(fruit)#2 (2) {
    ["name"]=>
    string(4) "pear"
    ["colour"]=>
    string(6) "yellow"
  }
  [2]=>
  object(fruit)#3 (2) {
    ["name"]=>
    string(10) "watermelon"
    ["colour"]=>
    string(4) "pink"
  }
} 

PDO:：FETCH_INTO：要将行提取到类的现有实例中，请使用PDO:：：FETCH_INTO并将该对象作为第二个参数传递。

类必须将列名声明为公共成员，或者剧本会死的。

 <?php
class Test
{
    protected $cols;
    function __set($name, $value) {
        $this->cols[$name] = $value;
    }
    function __get($name) {
        return $this->cols[$name];
    }
}
$obj = new Test();
$db = PDOTest::factory();
$stmt = $db->prepare("select * from test");
$stmt->setFetchMode(PDO::FETCH_INTO, $obj);
$stmt->execute();
foreach ($stmt as $a) {
    print_r($a);
}
print_r($obj); // contains the same values as the last iteration above
?>