Walton Restos catalogue of expert engineers and crafts people includ.pdf
Walton Resto's catalogue of expert engineers and crafts people includes details of specialisms held by each of the experts. Initial data analysis identifies that the 'has expertise in' relationship can be described by Each expert must have expertise in one or more specialisms. Each specialism may be the expertise of one or more experts. This analysis results in initially producing the following entity-relationship diagram fragment (only showing primary keys for expert and specialism, and one additional attribute, Email, for expert. (In the Figure 4, NameString is the domain from which Names can be drawn, EmailString is the domain from which Email values can be drawn; Title is the domain from which Specialism values can be drawn): Figure 4 The initial 'has expertise in' relationship ERD a. Convert Figure 4 into a relational model, decomposing the HasExpertiseln relationship. Your diagram should show the relations, the attributes and any constraints required to represent the relationship shown. (As Figure 4 shows, use for any attributes not required to represent the HasExpertiseln relationship.) (10 marks) b. Constraints are important in relational representations. In the context of your solution to a) above, briefly explain: What constraints achieve in a relational model, and give 4 examples of different constraints in your solution explaining what each achieves..
Walton Restos catalogue of expert engineers and crafts people includ.pdf
Walton Resto's catalogue of expert engineers and crafts people includes details of specialisms held by each of the experts. Initial data analysis identifies that the 'has expertise in' relationship can be described by Each expert must have expertise in one or more specialisms. Each specialism may be the expertise of one or more experts. This analysis results in initially producing the following entity-relationship diagram fragment (only showing primary keys for expert and specialism, and one additional attribute, Email, for expert. (In the Figure 4, NameString is the domain from which Names can be drawn, EmailString is the domain from which Email values can be drawn; Title is the domain from which Specialism values can be drawn): Figure 4 The initial 'has expertise in' relationship ERD a. Convert Figure 4 into a relational model, decomposing the HasExpertiseln relationship. Your diagram should show the relations, the attributes and any constraints required to represent the relationship shown. (As Figure 4 shows, use for any attributes not required to represent the HasExpertiseln relationship.) (10 marks) b. Constraints are important in relational representations. In the context of your solution to a) above, briefly explain: What constraints achieve in a relational model, and give 4 examples of different constraints in your solution explaining what each achieves..
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Walton Restos catalogue of expert engineers and crafts people includ.pdf
- 1. Walton Resto's catalogue of expert engineers and crafts people includes details of specialisms held by each of the experts. Initial data analysis identifies that the 'has expertise in' relationship can be described by Each expert must have expertise in one or more specialisms. Each specialism may be the expertise of one or more experts. This analysis results in initially producing the following entity-relationship diagram fragment (only showing primary keys for expert and specialism, and one additional attribute, Email, for expert. (In the Figure 4, NameString is the domain from which Names can be drawn, EmailString is the domain from which Email values can be drawn; Title is the domain from which Specialism values can be drawn): Figure 4 The initial 'has expertise in' relationship ERD a. Convert Figure 4 into a relational model, decomposing the HasExpertiseln relationship. Your diagram should show the relations, the attributes and any constraints required to represent the relationship shown. (As Figure 4 shows, use for any attributes not required to represent the HasExpertiseln relationship.) (10 marks) b. Constraints are important in relational representations. In the context of your solution to a) above, briefly explain: What constraints achieve in a relational model, and give 4 examples of different constraints in your solution explaining what each achieves.