想问问有没有大神帮忙看看这个代码，对着书看着改了好久的PDO运行之后页面是空白的，真的不知道是哪里出了错误的，求求了




<?php
$dbms='mysql';
$user='root';
$pwd='';
$dbName='san';
$host="localhost";
$dsn = "$dbms:host=$host;dbname=$dbName";

try {
$pdo= new PDO($dsn,$user,$pwd);
$pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ATTR_ERRMODE_WARNING);
$query-"select*from tb_pdo_mysqls";
$result=$pdo->prepare($query);
$result->execute();
while ($res=$result->fetch(PDO::ATTR_FETCH_ASSOC)){
?>
<tr>
<td height="22" align="center" valign="middle"><?php echo $res['id'];?></td>
<td align="center" valign="middle"><?php echo $res["pdo_type"];?></td>
<td align="center" valign="middle"><?php echo $res["database_name"];?></td>
<td align="center" valign="middle"><?php echo $res["dates"];?></td>
</tr>

<?php
}
}catch (PDOException $e){
"Error!: " . $e->getMessage() . "<br/>";
die();
}
?>