What are the common errors or issues that can arise when passing parameters through URLs in PHP scripts, especially when dealing with database operations?

One common issue when passing parameters through URLs in PHP scripts is the lack of proper validation and sanitization, which can lead to SQL injection attacks. To prevent this, always sanitize and validate any user input before using it in database operations. Additionally, make sure to properly encode the parameters to avoid any encoding issues.

// Example of how to sanitize and validate parameters passed through URLs in PHP

// Get the parameter from the URL and sanitize it
$id = filter_input(INPUT_GET, 'id', FILTER_SANITIZE_NUMBER_INT);

// Validate the parameter
if(filter_var($id, FILTER_VALIDATE_INT)){
    // Proceed with database operation using the sanitized and validated parameter
    $query = "SELECT * FROM table WHERE id = $id";
    // Execute the query
} else {
    // Handle invalid input error
    echo "Invalid parameter";
}