我正在努力制作一个类，可以用来显示我的5个最新帖子和4个最受欢迎的帖子。我使用一个预先准备好的语句来完成这项工作，保留ORDERBY语句以包含两个不同的参数
问题是，当我运行这个程序时，我得到的结果是相同的（帖子的顺序相同）。我在主页上运行的代码是这样的：
<?php
$test = new SideBar();
echo $test->recent();
echo $test->popular(); // returns the same as recent() for some reason
?>
这就是
class SideBar
{
// Storing the names of the database table columns
private $id = 'n';
private $rating = 'mean';
private $stmt;
private $result;
public function __construct()
{
global $mysqli;
$this->stmt = $mysqli->prepare("SELECT n,title,date
FROM claims
WHERE active = 1
ORDER BY ? DESC
LIMIT 5");
}
public function recent()
{
$this->result = "";
return $this->build($this->id);
}
public function popular()
{
$this->result = "";
return $this->build($this->rating);
}
private function build($order)
{
$this->stmt->bind_param('s',$order);
$this->stmt->execute();
$this->stmt->bind_result($n, $title, $date);
while($this->stmt->fetch())
{
$this->result .= '<a href="[mydomain]?id='.$n.'">';
$this->result .= $title.' '.$date;
$this->result .= "</a>'n";
}
return $this->result;
}
public function __destruct()
{
$this->stmt->close();
}
}
显然，您不能将列名绑定到ORDERBY子句。相反，您可以在recent和popular函数中形成必要的查询，并将prepare pdo语句移动到build函数中。以下是修改：
public function __construct()
{
}
public function recent()
{
$this->result = "";
$q="SELECT n,title,date
FROM claims
WHERE active = 1
ORDER BY id DESC
LIMIT 5"
return $this->build($q);
}
public function popular()
{
$this->result = "";
$q="SELECT n,title,date
FROM claims
WHERE active = 1
ORDER BY mean DESC
LIMIT 5"
return $this->build($q);
}
private function build($query)
{
global $mysqli;
$stmt = $mysqli->prepare($query)
$stmt->execute();
$stmt->bind_result($n, $title, $date);
while($stmt->fetch())
{
$this->result .= '<a href="[mydomain]?id='.$n.'">';
$this->result .= $title.' '.$date;
$this->result .= "</a>'n";
}
return $this->result;
}