Figure 5-29 page 116
I have a question regarding the cardinality in the ER Diagram in figure 5-29 on page 116:
How come Order has a 1.N cardinality with Customer while Address and Contact have a 0.N cardinality?
The Customer needs at least one order, one address, and one contact, so shouldn't the cardinality be the same in all 3 relationships?
Thanks in advance for any help.