php 预编译查询始终fetch不到数据解决方案

<br />
include ('../db/MySqlConnect.php');<br />
$conn = new MySqlConnect();<br />
$mysqli = $conn->getConnection();<br />
$sql = 'select id, username, password from admin where id = ?';<br />
$seach_id = 1;<br />
settype($seach_id, "integer");<br />
if($stmt = $mysqli->prepare($sql)) {<br />
	$stmt->bind_param('i', $seach_id);<br />
	$stmt->execute();<br />
	$stmt->bind_result($rs_id, $rs_name, $rs_password);<br />
	if($stmt->fetch() == NULL) {<br />
		echo 'no result';<br />
	} else {<br />
		 printf('id:%s, name:%s, password:%s <br/>', $rs_id, $rs_name, $rs_password);<br />
	}<br />
	$stmt->close();<br />
	$mysqli->close();<br />
}<br />