public function getTables()
    {
        if (is_null($this->_tables)) {

            $result = $this->_adapter->query(
                $this->_getTablesSql,
                [$this->_adapter->getSchemaName()]
            );

            $names = [];
            foreach ($result as $table) {
                $names[] = $table['TABLE_NAME'];
            }
            $this->_tables = $names;
        }
        return $this->_tables;
    }