Error in my PHP "undefined index" and "you have an error in your SQL syntax"

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WOULD JUST LIKE TO START OFF THAT I AM USING PLESK AND MYSQL AND THESE ARE THE SET PLATFORMS I HAVE TO USE FOR THIS PROJECT

I have double checked form names, everything is correct yet I am still getting the error messages. This is my PHP code:

<?php
include 'db.inc.php';
echo "The details sent down are: <br>";
echo "Title : " . $_POST['title'] . "<br>";
echo "Provider : " . $_POST['provider'] . "<br>";
echo "Description : " . $_POST['desc'] . "<br>";
echo "Fee : " . $_POST['fee'] . "<br>";
echo "Venue : " . $_POST['ven'] . "<br>";
echo "Available Places : " . $_POST['avPlaces'] . "<br>";
echo "Remaining Places : " . $_POST['rePlaces'] . "<br>";
echo "Start Date : " . $_POST['date'] . "<br>";
echo "Days : " . $_POST['days'] . "<br>";
echo "Start Time : " . $_POST['start'] . "<br>";
echo "End Time :  " . $_POST['end'] . "<br>";

$sql = "Insert into courses (Title, Provider, Description,  Fee, Venue, AvPlaces, RePlaces, StartD, Days, StartT, EndT) Values ('$_POST[title]','$_POST[provider]','$_POST[desc]','$_POST[fee]','$_POST[ven]','$_POST[avPlaces]','$_POST[rePlaces]',$_POST[date]','$_POST[days]','$_POST[start]','$_POST[end]')";
if (!mysqli_query($con, $sql))
{
	die ("An error in the sql query: " . mysqli_error($con));
}

echo "<br>A record has been added for " . $_POST['Title'] . " " ;
header("refesh:3; url=addCourse.html");

mysqli_close($con);
?>
```

and this is my HTML code accompanying it:
```

<div class="contents">
		<form action="addCourse.php" method="post">
			<label for="title" class= "label" >Title:</label><br><br>
			<input type="text" class="field" id="title" name="title"><br><br>
			<label for="provider" class= "label" >Provider:</label><br><br>
			<input type="text" class= "field" id="provider" name="provider"><br><br>
			<label for="desc" class= "label" >Description:</label><br><br>
			<input type="text" class= "field" id="desc" name="desc"><br><br>
			<label for="fee" class= "label" >Fee:</label><br><br>
			<input type="number" class= "field" id="fee" name="fee"><br><br>
			<label for="ven" class= "label" >Venue:</label><br><br>
			<input type="text" class= "field" id="ven" name="ven"><br><br>
			<label for="avPlaces" class ="label">Available Places:</label><br><br>
			<input type="number" class= "field" id="avPlaces" name="avPlaces"><br><br>
			<label for="rePlaces" class="label">Remaining Places:</label><br><br>
			<input type="number" class="field" id="rePlaces" name="rePlaces"><br><br>
			<label for="date" class="label">Start Date:</label><br><br>
			<input type="date" class= "field" id="date" name="date"><br><br>
			<label for="days" class= "label">Days:</label><br><br>
			<input type="text" class= "field" id="day" name="day"><br><br>
			<label for="start" class= "label">Start Time:</label><br><br>
			<input type="time" class= "field" id="start" name="start"><br><br>
			<label for="end" class= "label">End Time:</label><br><br>
			<input type="time" class= "field" id="end" name="end"><br><br>
			<input type="submit" id ="add" name="add"><br><br>
			<input type="reset" id = "reset" name="reset"><br><br>
			</form>
			</div>

What I have tried:

I have tried as much as I can figure for now

Posted 26-Aug-21 5:23am

Megan Crean

Updated 26-Aug-21 6:16am

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Comments

Richard MacCutchan 26-Aug-21 11:36am

What is the complete text of the error message? Also have you checked the ouptut of all the echo statements?

Megan Crean 26-Aug-21 11:43am

I have ran my addCourse.html page to see what would happen and this was the output:
The details sent down are:
Title : Test
Provider : Test
Description : Test
Fee : 000
Venue : Test
Available Places : 00
Remaining Places : 00
Start Date : 2021-07-20
Notice: Undefined index: days in /var/www/vhosts/C00249687.candept.com/httpdocs/Summer Project 2021/addCourse.php on line 12 Days :
Start Time : 00:00
End Time : 00:00
Notice: Undefined index: days in /var/www/vhosts/C00249687.candept.com/httpdocs/Summer Project 2021/addCourse.php on line 16 An error in the sql query: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '','','00:00','00:00')' at line 1

I checked my database to see if anything went in and no data is stored there.

Richard Deeming 26-Aug-21 11:45am

Your code is vulnerable to SQL Injection[^]. NEVER use string concatenation to build a SQL query. ALWAYS use a parameterized query.

PHP: SQL Injection - Manual[^]
PHP: Prepared statements and stored procedures - Manual[^]

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Richard MacCutchan · Answer 1 · 2021-08-26T05:46:00

Solution 1

You have a spelling mistake: in the PHP code you are using 'days' ...

PHP

echo "Days : " . $_POST['days'] . "<br>";

... but in the HTML you are using 'day'

HTML

<label for="days" class= "label">Days:</label><br><br>
<input type="text" class= "field" id="day" name="day"><br><br>

Posted 26-Aug-21 5:46am

Richard MacCutchan

Comments

Megan Crean 26-Aug-21 11:55am

Hey, thank you for this. It resolved the Undefined Index for the days section I appreciate that. However I still have the An error in the sql query: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '','Test','00:00','00:00')' at line 1" error

Richard MacCutchan 26-Aug-21 12:05pm

Check your database schema to see what type is expected in the start time and end time fields. You should also be using a DateTime type for the start date, not a string.

Patrice T · Answer 2 · 2021-08-26T06:16:00

PHP

$sql = "Insert into courses (Title, Provider, Description,  Fee, Venue, AvPlaces, RePlaces, StartD, Days, StartT, EndT) Values ('$_POST[title]','$_POST[provider]','$_POST[desc]','$_POST[fee]','$_POST[ven]','$_POST[avPlaces]','$_POST[rePlaces]',$_POST[date]','$_POST[days]','$_POST[start]','$_POST[end]')";

Never build an SQL query by concatenating strings. Sooner or later, you will do it with user inputs, and this opens door to a vulnerability named "SQL injection", it is dangerous for your database and error prone.
A single quote in a name and your program crash. If a user input a name like "Brian O'Conner" can crash your app, it is an SQL injection vulnerability, and the crash is the least of the problems, a malicious user input and it is promoted to SQL commands with all credentials.
SQL injection - Wikipedia[^]
SQL Injection[^]
SQL Injection Attacks by Example[^]
PHP: SQL Injection - Manual[^]
How can I explain SQL injection without technical jargon? - Information Security Stack Exchange[^]