HW $5$

Construct an E$-$R diagram for a hospital with a set of patients and a set of medical doctors. Associate with each patient a log of the various tests and examinations conducted.

Explain the difference between a weak and a strong entity set.

Consider two entity sets A and $B$ that both have the attribute $x($among others whose names are not relevant to this question$).$

a$.$ If the two Xs are completely unrelated, how should the design be improved?

b$.$ If the two Xs represent the same property and it is one that applies both to A and to B $,$ how should the design be improved? Consider three subcases:

X is the primary key for A but not B

$x$ is the primary key for both A and $B$

X is not the primary key for A nor for B

Design an E$-$R diagram for keeping track of the scoring statistics of your favorite sports team. You should store the matches played, the scores in each match, the players in each match, and individual player scoring statistics for each match. Summary statistics should be modeled as derived attributes with an explanation as to how they are computed.

Construct appropriate relation schemas for the E$-$R diagram in Exercise $4.$

Extend the E$-$R diagram of Exercise $4$ to track the same information for all teams in a league.