Why is my data not stripping properly with mysql_real_escape_string? - php

Question

Here is my code below:
$studentTalking = mysql_real_escape_string($_POST['studentTalking']);
//Finally, we can actually the field with the student's information
$sql = <<<SQL
UPDATE `database` SET
`studentName`='$studentName',
`studentEmail`='{$data['studentEmail']}',
`studentPhone`='{$data['studentPhone']}',
`studentID`='{$data['studentID']}',
`studentTalking`= '{$studentTalking}',
`resume` = '{$data['resume']}'
WHERE `id`={$data['date_time']} AND (`studentName` IS NULL OR `studentName`='')
SQL;
I am trying to use the mysql_real_escape_string to allow apostrophes entered into our form by the user to go to the database without breaking the database, however the data will either go through as null or the apostrophe will break the database. I have changed everything I could think of, and can't figure out why this isn't working. Yes I understand the that injections could break our database, and we will work on updating the code soon to mysqli but we need this working now. I suspect my syntax isn't correct and the first line may need to be moved somewhere, but I am not the strongest in PHP and I am working with code that was written by previous interns. Thank you in advance.

Answer 1

Switch to mysqli_* functions is the right answer.
The answer if intend to stayg with the deprecated and dangerous mysql_* functions:
Here you set a new variable equal to your escaped $_POST[]:
$studentTalking = mysql_real_escape_string($_POST['studentTalking']);
But in your SQL you still refer to the $_POST array... Switch your SQL over to use your new variable you created
$sql = <<<SQL
UPDATE `tgtw_rsvp` SET
`studentName`='$studentName',
`studentEmail`='{$data['studentEmail']}',
`studentPhone`='{$data['studentPhone']}',
`studentID`='{$data['studentID']}',
`studentTalking`= '$studentTalking',
`resume` = '{$data['resume']}'
WHERE `id`={$data['date_time']} AND (`studentName` IS NULL OR `studentName`='')
SQL;

Answer 2

Because you are not using the stripped variable but still the raw POST data.