Answer 5_3_2

Question 2 

Question 2 The manager of a video hire shop uses a relational database management system to operate the business.  Separate database files hold details of customers, video tapes, and loans.  Customers can hire as many films as they wish.

(a) For each of the files mentioned above, identify the key fields and list other appropriate fields that will be required to enable the system to be maintained with minimum redundancy.

(b) Draw an ER diagram for the database.

(c) Describe three advantages of using a relational database rather than a flat file information storage system.

(a) In standard notation:

CUSTOMER (Customer ID, first name, surname, address 1, address 2, postcode, telephone)

LOAN (Customer ID, Video ID, date issued, date returned, fee)

VIDEO (Video ID, title, movie star, certificate)

(b)

(c) Advantages include:

• Avoidance of data redundancy (this was in the stem of the question);
• Only one centrally held set of data, which gets updated each time an application processes the data;
• Data integrity is assured;
• There is only one version of the data;
• It is easy to correct mistakes made on the data.

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