Q.2.2 Two interns were overheard arguing over which notation to use for entity relationship diagrams – Crow’s Foot, Chen or Unified Modelling Language (UML). It would be useful to see the three types of diagrams next to each other for comparison. Draw the below relationship in each of the three notations. “A space station orbits around one and only one planet. A planet may have none, one or more space stations in orbit around it.” Q.2.2.1Crow’s Foot. Q.2.2.2Chen. Q.2.2.3 Unified Modelling Language (UML).
Q.2.2
Two interns were overheard arguing over which notation to use for entity relationship diagrams – Crow’s Foot, Chen or Unified Modelling Language (UML). It would be useful to see the three types of diagrams next to each other for comparison. Draw the below relationship in each of the three notations.
“A space station orbits around one and only one planet.
A planet may have none, one or more space stations in orbit around it.”
Q.2.2.1Crow’s Foot.
Q.2.2.2Chen.
Q.2.2.3 Unified Modelling Language (UML).
Q.2.3 Somebody told Tshepo that data redundancy causes problems. And yet he has seen
Q.2.3.1 Explain what foreign keys are.
Q.2.3.2 Explain why foreign keys are not redundant data.
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