Mysqli-更新或插入（如果不存在）

Question

嗨，大家好，我有一张桌子，上面的PHP脚本

$host="host"; // Host name
$username="username"; // Mysql username
$password="password"; // Mysql password
$db_name="dbname"; // Database name
$tbl_name="table"; // Table name

// Connect to server and select database.
mysql_connect("$host", "$username", "$password")or die("cannot connect");
mysql_select_db("$db_name")or die("cannot select DB");

$url = "http://api.erpk.org/citizen/profile/3121752.json?key=Yn3AsG80";
$json = $json = file_get_contents($url);
$data = json_decode($json, true);

// Get values from form
$id=$_GET['id'];
$citid=$data['id'];
$citname=$data['name'];
$level=$data['level'];
$status=$data['army']['role'];
$citizenship=$data['citizenship']['name'];
$mu=$data['army']['name'];

// update data in mysql database
$sql="UPDATE $tbl_name SET citid='$citid', citname='$citname', level='$level', status='$status', status='$status', citizenship='$citizenship', mu='$mu' WHERE id='$id'";
$result=mysql_query($sql);

// if successfully updated.
if($result){
echo "Successful";
echo "<BR>";
echo "<a href='list_records.php'>View result</a>";
}

else {
echo "ERROR";
}

这是我的问题，更新表单可以正常工作，但是当它成功时，即使通过，数据也不会更新

// if successfully updated.

我在哪里弄错了，我不确定