2.12

Consider the bank database of Figure 2.18. Assume that branch names and customer names uniquely identify branches and customers, but loans and accounts can be associated with moren than one customer.
a. What are the appropriate primary keys?
b. Given your choice of primary keys, identify appropriate foreign keys.

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Relation Name	Primary key
branch	branch_name
customer	ID
loan	loan_number
borrower	{ID, loan_number}
account	account_number
depositor	{ID, account_number}

2. Relation Name	Foreign key
   branch	No Foreign Key
   customer	No Foreign Key
   loan	branch_name
   borrower	ID - a foreign key referencing customer relation, loan_number - a foreign key referencing loan relation
   account	branch_name
   depositor	ID - a foreign key referencing customer relation, account_number - a foreign key referencing account relation