protected function getTables()
    {
        if (empty($this->config['tables'])) {
            return '';
        }
        $tables = [];
        // Tables specified in both tables and structureTables should only
        // export their structure. @see getStructureTables().
        $allTables = array_diff($this->config['tables'], $this->config['structureTables']);
        foreach ($allTables as $table) {
            $tables[] = escapeshellarg($table);
        }
        return implode($tables);
    }