CODEWITHSUNDEEP
php
TechieMickey
TechieMickey

Reputation: 63

How to resolve undefined error in php

<?php

   $conn = new mysqli("localhost", "root", "", "hcis") or die(mysqli_error());
   $q = $conn->query("SELECT * FROM `vaccine` NATURAL JOIN `itr` WHERE `itr_no` = '$_GET[itr_no]' && `epi_id` = '$_GET[epi_id]'") or die(mysqli_error());
   $f = $q->fetch_array();

?>

This is my code. I am getting this error

Notice: Undefined index: itr_no in C:\xampp\htdocs\thesis\admin\epi_print.php on line 25

Notice: Undefined index: epi_id in C:\xampp\htdocs\thesis\admin\epi_print.php on line 25

I tried googling it and found that I have to use isset but I do not know where to put the isset.

Upvotes: 0

Views: 91

Answers (5)

Ngo Tuan
Ngo Tuan

Reputation: 205

isset() is used to check if the variable is set and is not null. Details: https://php.net/manual/en/function.isset.php.

So you should use isset() before you access the $variable. For example:

if (isset($example['id']) {
    echo $example['id'];
}

The example above makes sure that if $example['id'] is set, you can access it. If you don't have isset, the echo would run even if $example['id'] was null or undefined - and that would throw an error.

@techiemickey: however, you error is caused by the reason that, you access var in the wrong way. You shout use $_GET['itr_no'] instead of $_GET[itr_no]

Upvotes: 0

Pupil
Pupil

Reputation: 23958

You query is vulnerable as you are passing url variables (user input directly) to database query.

Use isset() for checking whether the variable we are using is defined.

Corrected code should be:

$itr_no = isset($_GET['itr_no']) ? $_GET['itr_no'] : '';
$epi_id = isset($_GET['epi_id']) ? $_GET['epi_id'] : '';

$itr_no = $conn->real_escape_string($itr_no);
$epi_id = $conn->real_escape_string($epi_id);

$conn = new mysqli("localhost", "root", "", "hcis") or die(mysqli_error());
$q = $conn->query("SELECT * FROM `vaccine` NATURAL JOIN `itr` WHERE `itr_no` = '$itr_no' && `epi_id` = '$epi_id'") or die(mysqli_error());
$f = $q->fetch_array();

Upvotes: 2

Ritesh Khatri
Ritesh Khatri

Reputation: 1301

You need surround you form data like, $GET['id'] Your edited code 

<?php

    $conn = new mysqli("localhost", "root", "", "hcis") or die(mysqli_error());
    $q = $conn->query("SELECT * FROM `vaccine` NATURAL JOIN `itr` WHERE `itr_no` = '$_GET['itr_no']' && `epi_id` = '$_GET['epi_id']'");
    $f = $q->fetch_array();

  ?>

Upvotes: 0

Sanjay Kumar Singh
Sanjay Kumar Singh

Reputation: 937

Using isset() to check your $_GET request value,

<?php

   $conn = new mysqli("localhost", "root", "", "hcis") or die(mysqli_error());

   //Checkes Whether itr_no And epi_id is available or not
   //runs when all are available
   if(isset($_GET['itr_no']) && isset($_GET['epi_id'])){
     $q = $conn->query("SELECT * FROM `vaccine` NATURAL JOIN `itr` WHERE `itr_no` = '$_GET[itr_no]' && `epi_id` = '$_GET[epi_id]'") or die(mysqli_error());
     $f = $q->fetch_array();
   }

?>

Use empty() to check $_GET request value

<?php

   $conn = new mysqli("localhost", "root", "", "hcis") or die(mysqli_error());

   //Checkes Whether itr_no And epi_id is available or not
   //runs when all are available
   if(!empty($_GET['itr_no']) && !empty($_GET['epi_id'])){
     $q = $conn->query("SELECT * FROM `vaccine` NATURAL JOIN `itr` WHERE `itr_no` = '$_GET[itr_no]' && `epi_id` = '$_GET[epi_id]'") or die(mysqli_error());
     $f = $q->fetch_array();
   }

?>

If you don't want to check using if then at starting you should use to check your $_GET request values like,

$itr_no = isset($_GET['itr_no']) ? $_GET['itr_no'] : '';
$epi_id = isset($_GET['epi_id']) ? $_GET['epi_id'] : '';

Upvotes: 1

Ravi
Ravi

Reputation: 31407

having this udefined error again and again

Because, you are trying to access index of an array, which is not defined. In your case, you are trying to access index itr_no and epi_id from array $_GET.

  1. Verify your URL query string of request, if it contains or may be your form.

or

  1. check if value isset before accessing it

    if(isset($_GET['itr_no']) && isset($_GET['epi_id'])){

Upvotes: 1

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