CODEWITHSUNDEEP
phphtmlmysql
user1770049
user1770049

Reputation: 29

What's causing undefined index error?

<?php 
  mysql_connect("localhost","root",""); 
  mysql_select_db("sample") or die("database could not connect "); 
?> 
<html> 
<head>
<meta name="description" content="Php Code for View, Search, Edit and Delete 
Record" />
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> 
<title>View Student  Record</title>
</head>
<body>
<center><h1><u>Student Database</u></h1></center>
<?php
  $roll=$_GET["roll"]; 
  $query="select * from student where roll='$roll'"; 
  $result=mysql_query($query);
  while ($row = mysql_fetch_array($result)) { 
  }
?>
<table style=" border:1px solid silver" cellpadding="5px" cellspacing="0px" 
align="center" border="1">
<tr>
<td colspan="4" style="background:#0066FF; color:#FFFFFF; font-size:20px">VIEW 
STUDENT DATABASE</td></tr>
<tr>
<td> Roll Number</td><td><? echo $row[0];?></td> 
<td> Class</td><td><? echo $row[1];?></td> 
</tr>
<tr>
<td> Name of Student</td><td><? echo $row[2];?></td> 
</tr>
<tr>
<td>Sex</td><td><? echo $row[3];?></td> 
<td>Address1</td><td><? echo $row[4];?></td></tr>
<tr> 
<td>Address2</td><td><? echo $row[5];?></td> 
<td>Address3</td><td><? echo $row[6];?></td></tr> 
<tr>
<td>Remarks</td><td><? echo $row[7];?></td></tr> 
<tr>
</table>
<p align="center"><a href="index.php">Go Back to Home</a></p> 
</body>
</html>

that is my code

<?php 
  $roll=$_GET["roll"]; 
  $query="select * from student where roll='$roll'";
  $result=mysql_query($query);
  while ($row = mysql_fetch_array($result)) {
  }
?>

Here's my problem. I don't know how to get rid of this error:

Notice: Undefined index: roll in C:\xampp\htdocs\sample\view.php on line 16

Line 16 is $roll=$_GET["roll"];.

This code should display the information in each row, but as I run it, it shows nothing.

Upvotes: 1

Views: 1576

Answers (3)

bfavaretto
bfavaretto

Reputation: 71918

Make sure you pass roll on the querystring. Without that, none of your PHP code makes sense. You're getting data from MySql based on $roll and trying to display it; if there's no value on that variable, there's no data. So add isset as Phil suggested, and dot run any PHP if it's not set.

Also, get rid of the while loop, and only execute $row = mysql_fetch_array($result) once, and only if isset($_GET['roll']). Otherwise, you'll try to echo false later on your code.

Upvotes: 1

Furry
Furry

Reputation: 345

Place this code below $roll=$_GET["roll"]; 

if (isset($_GET["roll"))
{
// IF TRUE, DO THE QUERY ECHO YOUR RESULT
}

?>

Upvotes: 0

Phil
Phil

Reputation: 164760

Your issue is an undefined $_GET index. Use isset(), eg

$roll = isset($_GET['roll']) ? $_GET['roll'] : null; // or a suitable default

Try something like this to fix your query loop

$result=mysql_query($query);
?>

<table style=" border:1px solid silver" cellpadding="5px" cellspacing="0px" align="center" border="1">
<tr>
<td colspan="4" style="background:#0066FF; color:#FFFFFF; font-size:20px">VIEW 
STUDENT DATABASE</td></tr>

<?php while ($row = mysql_fetch_array($result)) : ?>

<!-- rows, cells and echos, etc -->

<?php endwhile ?>

</table>

And finally, the MySQL extension is now deprecated. I strongly recommend you switch to PDO. Using PDOStatement::bindParam() would also solve your SQL injection vulnerability in mysql_query().

Upvotes: 1

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