试图通过PHP编辑SQL但不断收到错误

Question

as far as i can see my code is sound however, I keep getting an error this is the error

Notice: Undefined variable: person in \sql\modify.php on line 12

here is my code..

<?php
include 'includes/connection.php';

if (!isset($_POST['submit'])){
    $q = "SELECT * FROM people WHERE ID = $_GET[id]";
    $result = mysql_query($q);
    $person = mysql_fetch_array($result);       
    }
?>
<h1>You are modifying A User</h1>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
Name<input type="text" name="inputName" value="<?php echo $person['Name']; ?>" /><br />
Description<input type="text" name="inputDesc" value="<?php echo $person['Description']; ?>" />
<br />
<input type="hidden" name="id" value="<?php echo $_GET['id']; ?>" />
<input type="submit" name="submit" value="Modify"/>
</form>
<?php
 if(isset($_POST['sumbmit'])) {   

$u = "UPDATE people SET `Name` = '$_POST[inputName]', `Description` = '$_POST[inputDesc]' WHERE ID = $_POST[id]";
  mysql_query($u) or die(mysql_error());

 echo "User has been modify";
 header("Location: index.php");

}
?>

any Thoughts or am im I just blind???

Answer 1

<?php
include 'includes/connection.php';

// set $person veriable
if (!isset($_POST['submit'])){
  $q = "SELECT * FROM people WHERE ID = $_GET[id]";
  $result = mysql_query($q);
  $person = mysql_fetch_array($result);       
}
// if form submit you use update and redirect
else {
  $u = "UPDATE people SET `Name` = '$_POST[inputName]', `Description` =      '$_POST[inputDesc]' WHERE ID = $_POST[id]";
  mysql_query($u) or die(mysql_error()); 

  //echo "User has been modify"; // this not need, bcz execute header('location') redirect you current page
  header("Location: index.php");
  exit(); //use it after header location
}
?>
<h1>You are modifying A User</h1>
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
Name<input type="text" name="inputName" value="<?php echo $person['Name']; ?>" /><br />
Description<input type="text" name="inputDesc" value="<?php echo $person['Description']; ?>" />
<br />
<input type="hidden" name="id" value="<?php echo $_GET['id']; ?>" />
<input type="submit" name="submit" value="Modify"/>
</form>