What potential issues or errors could arise from the handling of the $subj variable in the script?

The $subj variable could potentially contain user input that is not properly sanitized, leading to security vulnerabilities such as SQL injection or cross-site scripting attacks. To mitigate this risk, it is important to sanitize and validate the input before using it in any database queries or output to the user. 

// Sanitize and validate the $subj variable before using it
$subj = filter_var($_POST['subj'], FILTER_SANITIZE_STRING);

// Use prepared statements to prevent SQL injection
$stmt = $pdo->prepare("SELECT * FROM table WHERE subject = :subject");
$stmt->bindParam(':subject', $subj);
$stmt->execute();

// Output the sanitized $subj variable
echo "Subject: " . htmlspecialchars($subj);

Keywords

variable handling PHP error handling data validation security vulnerabilities

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