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Having this ER diagram how do I read the relationship between account and customer? I thought to read as follows "A customer can have N accounts, and an account is always associated with M clients" this way of reading is correct to describe relationships M:N?
I understand that the representation used means: An account associated with 1 or more customers and a client may be associated with 0 or more accounts. Now it seems strange to me that a customer can exist without being associated with an account, but if that is what is specified in your requirements then just follow them.
– anonimo
This example also does not make much sense to me, however it is what is present in the book for which I am studying. Then my reading is partially correct ? I would only need to better describe the minimum and maximum cardinality ?
– Matheus
From what I understand the double line indicates a mandatory, ie, defines the minimum cardinality.
– anonimo