That I know of course. may be my question was not clear.
I am assuming the max. number of items in the shop are 2000 items:
PRODUCTS ID from 1-2000
I do not know how many customers AND orders there will be. But I can imagine 200,000 customers and 2,000,000 orders:
CUSTOMERS ID from 2000-200000
ORDERS ID from 200,001-2,000,000
I am assigning the other tables ID's in that way. Is this the right way to do?
Or I can have the same set of integers for any ID without any problem such as this one
CUSTOMERS ID from 2000-200000
ORDERS ID from 2000-200000
If the database is designed right way from the beginning, it would make less headache in the future incase I need to improve it.