Question

I have a little problem with a PHP code that was supposed to edit database table. Instead, it’s giving me ‘person not defined error – pointing to lines 18 and 19. And down the code, it says ‘id’ is undefined as well.

<?php
    $con = mysql_connect("localhost","myuser","mypass");
if (!$con)
  {
  die('Could not connect: ' . mysql_error());
  }

    mysql_select_db("mydb", $con);
    if(!isset($_POST['submit'])){
    $q = "SELECT * FROM person WHERE id = $_GET[id]";
    $result = mysql_query($q) or die(mysql_error());
    $person = mysql_fetch_array($result);
    }
?>

<h1>You are Modifying A Record</h1>
  <form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
    Name:<input type="text" name="myname" id="myname" value ="<?php echo $person['name']; ?>" /> <br />
    Description: <input type="text" name="mydescription" id="mydescription" 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['submit'])){
    $q = "UPDATE person SET `name`='$_POST[myname]', `description`='$_POST[mydescription]' WHERE id = $_POST[id]";
     mysql_query($q) or die(mysql_error());
     //header('Location: select.php');
     echo 'User has been modified successfully!';
     }else{

     }
?>

Thanks for your help.

Answer 1

Well, you’re only conditionally defining $person. So, the first time you view the page, PHP should show an error.

You can fix this by adding an “else” clause:

if(!isset($_POST['submit'])){
    $q = "SELECT * FROM person WHERE id = $_GET[id]";
    $result = mysql_query($q) or die(mysql_error());
    $person = mysql_fetch_array($result);
}
else
{
    $person = array( 'name'=> '', 'description'=>'' );
}

As to $_GET[ ‘id’ ], are you going to the page with an ?id=<value> in the url? If not, then $_GET[ ‘id’ ] will be undefined.