Getting Undefined Index using While statement in PHP

Question

I have the following code

$sqlSubscription = "SELECT `user_id` FROM subscriptions WHERE `user_id` = '".$user_id."' and `course_id` = 'calculus_1'";
            $subscriptionResult = mysql_query($sqlSubscription);

            if($subscriptionResult === FALSE) {
    die(mysql_error()); // temp error handling
              }


                while ($rows = mysql_fetch_assoc($subscriptionResult))
                    {
                        $user_id = $rows['user_id'];
                        $course_id = $rows['course_id'];
                        if($user_id==1 && $course_id="calculus_1")

                            {

                                //do some work


                            }

                     }

I'm getting the error Notice: Undefined index: course_id The line that causes the error is in the while statement $course_id = $rows['course_id']; The strange part is that I can select from where both user and course ids match, and there aren't any errors doing something simple like an echo, but when I add this while statement to verify that both the user and course_ids match a certain rule before outputting data I get this error.

Here is an export of the PHP Arrays through phpMyAdmin

<?php
/**
 * Export to PHP Array plugin for PHPMyAdmin
 * @version 0.2b
 */

//
// Database `test`
//

// `escholars`.`subscriptions`
$subscriptions = array(
  array('user_id' => 'test','course_id' => 'calculus_1','start_date' => '2013-09-12','end_date' => '2013-09-28')
);

Any ideas?

Thanks

Please, don't use mysql_* functions in new code. They are no longer maintained and are officially deprecated. See the red box? Learn about prepared statements instead, and use PDO or MySQLi - this article will help you decide which. If you choose PDO, here is a good tutorial. — h2ooooooo
– h2ooooooo, Commented Sep 12, 2013 at 16:44

Sbml · Accepted Answer · 2013-09-12 16:48:43Z

2

To compare you need == signs

if($user_id==1 && $course_id=="calculus_1")

And you are selecting something WHERE course_id="something" so you don't need to return the same value from database $rows['course_id']

$course_id = "calculus_1";

edited Sep 12, 2013 at 16:48

answered Sep 12, 2013 at 16:43

Sbml

1,9172 gold badges17 silver badges27 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

maestro416 Over a year ago

in the case that i need to verify that two values are met, for example user_id = test and course_id = calculus, how would i setup that if statement using the while loop that i have?

showdev Over a year ago

That's a good point, Sbml. The course_id is hardcoded in the query. So, in this context, no need to fetch it back out again.

showdev · Accepted Answer · 2013-09-12 16:43:04Z

1

You do not appear to be selecting the course_id.

You'll need to select it in order to include it in the result set. Otherwise it will not be included in your fetched array and will be undefined.

Try this:

SELECT `user_id`,`course_id` FROM .....

answered Sep 12, 2013 at 16:43

showdev

29.3k37 gold badges61 silver badges82 bronze badges

1 Comment

J_D Over a year ago

To add on, you can always either define the var before doing the while loop, or turn down the error reporting so it won't show these notices, but making it part of the SQL will be a more permanent fix

Collectives™ on Stack Overflow

Getting Undefined Index using While statement in PHP

2 Answers 2

2 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related