![]() ![]() e.g., the bank balance must be updated when a deposit is made. Occurrence of a real-world event update database.Read client's balance in the database and output it, when the Request Balance Transaction is performed. Cause the occurrence of a real-world event.Deposit transaction: update customer's balance in the database. Withdraw transaction: dispense cash (and update the customer's balance in the database). The execution of each transaction must maintain the relationship between the database state and the business state.Either all or none of the transactions of the real-world event are performed.Student either registers or does not register Similarly, the system must ensure that either the corresponding transaction runs to completion or, if not, it has no effect at all. ![]() ![]() Business Rules limit the occurrence of certain real-world events. A consistent database state does not necessarily model the actual state of the business.Such limitations are also expressed as integrity constraints.Ī database is consistent if all static integrity constraints are satisfied.cur_reg = |list_of_registered_students|.Other static consistency requirements are related to the fact that the database might store the same information in various ways.These limitations are called (static) integrity constraints: assertions that must be satisfied by all database states.Correspondingly, allowable database states are restricted.Student cannot register for a course if the current number of registrants equals the maximum allowed. ![]()
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