Example of a PHP class that stores dynamic properties in an array

example.php

<?php
$db = new PDO(/* some database credentials */);

$someUserData = [
    'email' => 'example@example.com',
    'user' => 'Example'
];

$user = new User($someUserData);

$user->active = true;
$user->admin = false;

$sqlParams = [];
$insertSql = $user->getInsertSqlStatement('users', $sqlParams);
// INSERT INTO `users`(email, user, active, admin) 
// VALUES(:email, :user, :active, :admin);


$statement = $pdo->prepare($insertSql);
$statement->execute($sqlParams);

User.php

<?php
/**
 * Example of a PHP class that stores dynamic properties in an array, and then can be used to create a SQL statement
 *
 * I would consider this a proof-of-concept and I do not believe this is a good practice
 */
class User
{
    /**
     * @var array Object attributes
     */
    private $attrs = [];

    public function __construct(array $attributes = [])
    {
        $this->attrs = $attributes;
    }

    public function __get(string $attrName)
    {
        return $this->attrs[$attrName] ?? null;
    }

    public function __set(string $attrName, $attrValue): void
    {
        $this->attrs[$attrName] = $attrValue;
    }

    /**
     * Returns the array of object attributes
     *
     * @return array
     */
    public function getAttrs(): array
    {
        return $this->attrs;
    }

    /**
     * Generates an insert SQL statement using the attribute keys as column names
     *
     * @param string $tableName The name of the table for which the insert statement is being created
     * @param array $parameters An array of parameters that will be filled from the object attributes
     * @return string The completed SQL statement
     */
    public function getInsertSqlStatement(string $tableName, array &$parameters): string
    {
        foreach($this->attrs as $attrKey => $attrValue) {
            $placeholder = preg_replace('@\W@', '_', $attrKey);
            $parameters[$placeholder] = $attrValue;
        }

        $columnNames =  '`' . implode('`, `', array_keys($this->attrs)) . '`';
        $placeholders = ':' . implode(', :', array_keys($parameters));

        $sql = <<<SQL
INSERT INTO `$tableName` ($columnNames)
VALUES ($placeholders)
SQL;
        return $sql;
    }
}