Question 1 4 Marks Data Modelling According to the ER model given above, answer either yes or no to the following questions: (a) Can a job belong to more than one customer? (1 mark) (b) Every installation must have at least one repair. (1 mark) (c) A job type can be neither an installation nor a repair. (1 mark) (d) If an installation is Wall/Window mounted, then it cannot be a ducted one. (1 mark) Question 2 4 Marks (a) Explain the total and partial specialisations that have been used in the ER model. (1 mark) (b) List the reasons for using disjoint classification in the ER model. (1 mark) (c) List the discriminator attributes that have been used in the ER model. (1 mark) (d) Explain the use of multi-valued attribute in the ER model. (1 mark) Question 3 5 Marks Converting ER models Convert the ER model given in Part A into a set of relations that satisfy Third Normal Form (3NF). You do not need to show your workings. You do not need to justify that they are in 3NF at this stage. You do not need to show sample data. Just show your relations. You should write your relations in either format shown below:
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