Change the table comment after created the table is not supported now?
Like mysql : ALTER TABLE [tableName] COMMNET [comment]; 
The sql "ALTER TABLE `system`.tables UPDATE Comment='test' WHERE NAME='t1';" also not supported!!!
My version is '21.9.4.35'。
real_column_names.push_back(column_name);
    }
    /** Just in case, turn off optimization "transfer to PREWHERE",
      * since there is no certainty that it works when one of table is MergeTree and other is not.
      */
    auto modified_context = Context::createCopy(local_context);
    modified_context->setSetting("optimize_move_to_prewhere", false);
    
    Block header = getHeaderForProcessingStage(*this, column_names, metadata_snapshot, query_info, local_context, processed_stage);
    /** First we make list of selected tables to find out its size.
      * This is necessary to correctly pass the recommended number of threads to each table.
      */
    StorageListWithLocks selected_tables
        = getSelectedTables(local_context, query_info.query, has_database_virtual_column, has_table_virtual_column);
    if (selected_tables.empty())
        
        return createSources(
            {},
            query_info,
            processed_stage,
            max_block_size,
            header,
            {},
            {},
            real_column_names,
            modified_context,
            0,
            has_database_virtual_column,
            has_table_virtual_column);
    size_t tables_count = selected_tables.size();