为什么我的查询没有返回带有 PDO 的行？ [复制]

Question

我正在使用 PHP 的 PDO 选项，但奇怪的是它不起作用。我认为是因为参数的绑定，但我不确定。谁能帮帮我。

if(isset($_POST['submit']))
{

    $query = "SELECT * FROM occasions WHERE naam IS NOT NULL";
    
    $stmt = $pdo->prepare($query);
    
    
    if (isset($_POST['merk'])) {
        $query .= " AND merk = :merk";
        
        $merk = $_POST['merk'];
        
        $stmt->bindParam(':merk', $merk);
    } 
    
    
    if($stmt->execute())
    {
        echo "query is executed";
        print_r($query);
    }
    else
    {
        echo "query is niet executed";
    }
    
    
    while($result = $stmt->fetch())
    {
        echo "<br>";
        echo $result['naam'];
    }
    
    
    
}

Answer 1

这是构建代码的更好方法。尝试这个。我相信这会奏效。

$merk = (!empty($_POST['merk']))?$_POST['merk']:null;
$brandstof = (!empty($_POST['brandstof']))?$_POST['brandstof']:null;

if(isset($_POST['submit'])){
  $query = "SELECT * FROM occassions WHERE naam IS NOT NULL";

  if($merk != null){
    $query .= " AND merk = :merk";
  }

  if($brandstof != null){
    $query .= " AND brandstof = :brandstof";
  }

  $stmt = $pdo->prepare($query);

  if($merk != null){
    $stmt-> bindValue(':merk', $merk);
  }

  if($brandstoff != null){
    $stmt-> bindValue(':brandstof', $brandstof);
  }

  $stmt-> execute();

  while($result = $stmt->fetch()){
    echo "<br>";
    echo $result['naam'];
  }
}