trying to edit SQL via php but keep getting an error - php

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>

Answer 2

You just need to check if you actually got output.
Just a plain example:
if ($person):
?>
<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
endif;
Remember to always validate your input and output, but also if queries you try to run do produce a result set.

Answer 3

Here's the issue:
<?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);
}
?>
At this point $person is set only if the form hasn't been submitted; but later on:
Name<input type="text" name="inputName" value="<?php echo $person['Name']; ?>" /><br />
Description<input type="text" name="inputDesc" value="<?php echo $person['Description']; ?>" />
You're using it anyway. If the form has been submitted, then you're going to get the warning you're seeing. What you need to do is something like:
if (isset($_POST['submit'])){
$name = $_POST['name'];
$description = $_POST['description']
} else {
$q = "SELECT * FROM people WHERE ID = $_GET[id]";
$result = mysql_query($q);
$person = mysql_fetch_array($result);
$name = $person['name'];
$description= $person['description'];
}
And then:
Name<input type="text" name="inputName" value="<?php echo $name ?>" /><br />
Description<input type="text" name="inputDesc" value="<?php echo $description; ?>" />
The variables are now set either way.
A couple of other things - you're not doing any error checking to see if your query has worked; if the query fails, your code will carry on regardless.
Secondly, the mysql_ functions are deprecated and will stop working at some point; you should look at moving to using mysqli_* or PDO instead.