Inspecting SQL Statements with debugDumpParams()

The debugDumpParams() method is designed to output information about a prepared statement directly to the screen. It dumps the original SQL command, the number of parameters used, and details about each parameter (its name, type, and value). This is extremely useful during debugging when you want to verify if PHP is actually sending the expected data to the database.

EXAMPLE

<?php
class Database {
    private $server = "localhost";
    private $username = "root";
    private $password = "";
    private $db_name = "pdo_db";
    public $connection;

    public function __construct() {
        try {
            // Added charset=utf8mb4 for character support
            $dsn = "mysql:host=" . $this->server . ";dbname=" . $this->db_name . ";charset=utf8mb4";
            $this->connection = new PDO($dsn, $this->username, $this->password);
            $this->connection->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        } catch(PDOException $e) {
            die("Connection failed: " . $e->getMessage());
        }
    }

    public function checkStatement($id) {
        $sql = "SELECT * FROM users WHERE id = :id";
        $statement = $this->connection->prepare($sql);
        $statement->bindValue(':id', $id, PDO::PARAM_INT);
        $statement->execute();

        // Output the statement details for debugging purposes
        echo "<pre>";
        $statement->debugDumpParams();
        echo "</pre>";
        
        $statement->closeCursor();
    }
}

// PART 3: Usage
$db = new Database();
$db->checkStatement(1);
?>

RESULT

The result will be displayed here...

Practical Application: This method is only used during application development. When the code does not return the expected results, we call debugDumpParams() to look "under the hood" of the prepared statement. Check the process at home by following these steps:

Start the Apache and MySQL modules in the XAMPP control panel.
Ensure via phpMyAdmin that the users table exists within the pdo_db database.
The method does not return a value, but instead prints data directly to the output stream.
Insert the example below into your PHP file and observe the detailed dump of the SQL statement metadata.