BANK database
Q1. Consider the given ER diagram for part of a BANK database (attached for reference). Each bank can have multiple branches, and each branch can have multiple accounts and loans.
(a) List the strong (nonweak) entity types in the ER diagram.
(b) Is there a weak entity type? If so, give its name, its partial key, and its identifying relationship.
(c) What constraints do the partial key and the identifying relationship of the weak entity type specify in this diagram?
(d) List the names of all relationship types, and specify the (min,max) constraint on each participation of an entity type in a relationship type. Justify your choices.
Sample Answer
a) The strong (nonweak) entity types in the ER diagram are:
- Bank
- Branch
- Account
- Loan
(b) Yes, there is a weak entity type in the ER diagram. It is the Account entity type. The partial key of the Account entity type is account_number. The identifying relationship of the Account entity type is the has_account relationship.