private function createIfNotExists()
    {
        $table = new Table('schema_migration');
        if ($this->info->isTableExists($table)) {
            return;
        }
        $primaryKey = new PrimaryKey(array('version'));
        $primaryKey->disableAutoIncrement();

        $table->addConstraint($primaryKey);
        $table
            ->addColumn(new BigIntegerColumn('version'))
            ->addColumn(new DateTimeColumn('created_at', array('nullable' => false, 'default' => 'now()')));
        $this->manipulation->create($table);
    }