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'。
ContextPtr query_context,
    const ASTPtr & query ,
    bool filter_by_database_virtual_column ,
    bool filter_by_table_virtual_column ) const
{
    assert(!filter_by_database_virtual_column || !filter_by_table_virtual_column || query);
    const Settings & settings = query_context->getSettingsRef();
    StorageListWithLocks selected_tables;
    DatabaseTablesIterators database_table_iterators = getDatabaseIterators(getContext());
    MutableColumnPtr database_name_virtual_column;
    MutableColumnPtr table_name_virtual_column;
    if (filter_by_database_virtual_column)
    {
        database_name_virtual_column = ColumnString::create();
    }
    if (filter_by_table_virtual_column)
    {
        table_name_virtual_column = ColumnString::create();
    }