PHP, mysql query inserting triple the amount of records when using foreach loop.

Interesting and weird problem with my code.  I have a form in which a person selects a single student or all students in one select input.  

If they select all students, the information gets passed like this: $student=5,3,7,4,1,2

The problem I am seeing is that when I try to input the students into the system it's tripling the records.  There should only be 6 records, but I'm getting 18.

Here's the code:
$userid = $_GET['userid'];
$student = $_GET['student'];
$date = $_GET['date'];
$type = $_GET['type'];
$subtype = $_GET['subtype'];
$notes = mysql_real_escape_string($_GET['notes']);
if (strpos($student,',') !== false) {
	$students = explode(",", $student);
	foreach($students as &$value) {
		mysql_query("INSERT INTO b2b_a_events (studentId, eventType, eventSubType, notes, dateOfEvent, userid) VALUES ($value, $type, $subtype, '$notes', '$date', $userid)") or die(mysql_error());
	}
} else {
	mysql_query("INSERT INTO b2b_a_events (studentId, eventType, eventSubType, notes, dateOfEvent, userid) VALUES ($student, $type, $subtype, '$notes', '$date', $userid)") or die(mysql_error());	
}

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The same happens for the single student being selected.  Everything being entered into the system is being entered in 3 times...
Andrew DerseAsked:
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Ray PaseurConnect With a Mentor Commented:
Three dangerous things and one thing that may help you debug this.  

First dangerous thing: The script appears to be updating a data base on the basis of a GET request.  GET requests must be idempotent.  You must use a POST or PUT request if you're going to update the data base.  The consequences of doing it wrong include the risk that any GET access, even a search engine spider, can damage your data model.

Second dangerous thing: PHP is doing away with MySQL support.  To understand why and to find a database extension that will be supported in the future, please see this article.
http://www.experts-exchange.com/Web_Development/Web_Languages-Standards/PHP/PHP_Databases/A_11177-PHP-MySQL-Deprecated-as-of-PHP-5-5-0.html

Third dangerous thing: You must always escape external data.  It is never safe to assume that external data can be added to a query string without filtering it.

Hopefully helpful thing.  Amend the code so you can get a printout of the queries before you run them.  By creating the query string in a separate variable, instead of overloading the function call, we can see the queries that are about to be run.  Here is an example.

$userid  = $_GET['userid'];
$student = $_GET['student'];
$date    = $_GET['date'];
$type    = $_GET['type'];
$subtype = $_GET['subtype'];
$notes   = mysql_real_escape_string($_GET['notes']);

// IF THERE ARE COMMAS IN THE $student VARIABLE MAKE SEVERAL QUERIES
if (strpos($student,',') !== false) {
	$students = explode(",", $student);
	foreach($students as $value) {
		$query = "INSERT INTO b2b_a_events (studentId, eventType, eventSubType, notes, dateOfEvent, userid) VALUES ($value, $type, $subtype, '$notes', '$date', $userid)";
		echo PHP_EOL . $query;
		mysql_query($query) or die(mysql_error());
	}
} 

// IF THERE ARE NO COMMAS IN THE $student VARIABLE MAKE ONLY ONE QUERY
else {
	$query = "INSERT INTO b2b_a_events (studentId, eventType, eventSubType, notes, dateOfEvent, userid) VALUES ($student, $type, $subtype, '$notes', '$date', $userid)";
	echo PHP_EOL . $query;
	mysql_query($query) or die(mysql_error());	
}

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If you're new to PHP and want some good learning resources, this article may be able to help you find those, and more importantly, steer yourself away from the many obsolete and risky examples that litter the internet.
http://www.experts-exchange.com/Web_Development/Web_Languages-Standards/PHP/A_11769-And-by-the-way-I-am-new-to-PHP.html
0
 
Brian TaoSenior Business Solutions ConsultantCommented:
Have you tried to echo $student and see what's in there?
0
 
Tomas Helgi JohannssonCommented:
Hi!

Change the line 8
$students = explode(",", $student);
to
$students = explode(',', $student);

You can use var_dump($students) in your code (after line 8 ) to see the content of the array for debug purposes.

Regards,
    Tomas Helgi
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Andrew DerseAuthor Commented:
Excellent, thank you all for your advice.  I will check out each solution now and get back to you.
0
 
Andrew DerseAuthor Commented:
Great answer!  I have not been keeping up to date with the current PHP/MySQL standards and have to admit I was rushing this project.  Thanks for helping me to slow down and do it correctly.  Your solution worked perfectly.
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Ray PaseurCommented:
Thanks for the points and best of luck with your project, ~Ray
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