php - echo PDO 查询结果，返回空？

Question

我正在学习 PDO，所以请温柔地对待我!我试图回显使用 PDO 进行的查询，但字符串返回空。我在这里缺少什么？

PHP

$query = "SELECT 1 
          FROM table 
          WHERE c1 = :c1 && c2 = :c2"; 

$query_params = array( ':c1' => $c1, ':c2' => $c2 ); 
try{ 
    $stmt = $db->prepare($query); 
    $result = $stmt->execute($query_params); 
} 
catch(PDOException $ex){
    die("Failed to run query: " . $ex->getMessage());
}
$row = $stmt->fetch(); //Now $row should hold values of c1 & c2, right?

//This is What i've tried
echo "<script type='text/javascript'>alert('".$row."');</script>";
echo "<script type='text/javascript'>alert('".$row[0]."');</script>";
echo "<script type='text/javascript'>alert('".$row[1]."');</script>";
echo "<script type='text/javascript'>alert('".$row['c1']."');</script>";
echo "<script type='text/javascript'>alert('".$result."');</script>";

Answer 1

如果您需要一行，请使用SELECT * FROM table WHERE c1 = :c1 && c2 = :c2 LIMIT 1