public function __construct($pdo, $database = '', $tablePrefix = '', array $config = [])
{
$this->pdo = $pdo;
// First we will setup the default properties. We keep track of the DB
// name we are connected to since it is needed when some reflective
// type commands are run such as checking whether a table exists.
$this->database = $database;
$this->tablePrefix = $tablePrefix;
$this->config = $config;
// We need to initialize a query grammar and the query post processors
// which are both very important parts of the database abstractions
// so we initialize these to their default values while starting.
$this->useDefaultQueryGrammar();
$this->useDefaultPostProcessor();
}