When creating un initialized db, table functions defined before initialization get removed. Additionally, table fields under db would be nil when trying to extend them or add function to them.

Thus, an empty table should be in place and at initialization merge the result of table:extend with what has been already defined.

Note: This maybe tricky with __new_index and __index setup of sql.table. I may need to modify the function to add fields to self instead of sql.table