13. So I would like to know last know location of this letter, and when it goes missing.
17. Yes, you're right - a person in general or some courier
18. One letter can be stored in up to about 10 warehouse. However number of all warehouses is much higher - few hundreds (or maybe even thousands).
19. My idea was to store every client (sender / recipient) in database. So if some person have send or received at least one letter it in database is in database (but if person sends / receives more letters it is in database only once).
17. Yes, you're right - a person in general or some courier
18. One letter can be stored in up to about 10 warehouse. However number of all warehouses is much higher - few hundreds (or maybe even thousands).
19. My idea was to store every client (sender / recipient) in database. So if some person have send or received at least one letter it in database is in database (but if person sends / receives more letters it is in database only once).
