public function run(Connection $connection, $append = false)
    {
        if (!$append) {
            //in the future, resolve key constraints here
            foreach (array_unique($this->dropTables) as $table) {
                $connection->delete($table, [1 => 1], [\PDO::PARAM_INT]);
            }
        }

        foreach ($this->getSortedFixtures() as $fixture) {
            $this->runFixture($connection, $fixture);
        }
    }