Entity-relationship Diagram Exercises And Answers Pdf May 2026

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\textbfTask: Draw the ERD including entities, attributes, primary keys, and the many-to-many relationship with its attribute.

\sectionExercise 4: Hospital Management (Ternary Relationship) \textbfScenario: \\ A hospital records which doctor treats which patient on which date. \beginitemize \item \textbfDoctor: doctor\_id (PK), name, specialty. \item \textbfPatient: patient\_id (PK), name, illness. \item \textbfTreatment Date: date. \item A doctor may treat many patients on a given date; a patient may be treated by many doctors; and each treatment happens on a specific date. The combination (doctor, patient, date) is unique. \enditemize entity-relationship diagram exercises and answers pdf

\vspace2cm \noindent\rule\textwidth0.5pt \textbfAnswer: \beginfigure[H] \centering \begintikzpicture[node distance=2cm, auto] \node[rectangle, draw] (dept) DEPARTMENT \\ \tiny dept\_no (PK) \\ name \\ budget; \node[rectangle, draw, below=2cm of dept] (emp) EMPLOYEE \\ \tiny emp\_ID (PK) \\ name \\ salary;

\vspace2cm \noindent\rule\textwidth0.5pt \textbfAnswer: \beginfigure[H] \centering \begintikzpicture \node[rectangle, draw] (order) ORDER \\ \tiny order\_number (PK) \\ order\_date \\ customer\_name; \node[rectangle, draw, double, below=1.5cm of order] (item) LINE ITEM \\ \tiny (weak entity); \node[diamond, draw, aspect=2, left=0.5cm of $(order.south)!0.5!(item.north)$] (contains) CONTAINS; \draw (order) -- (contains); \draw (contains) -- (item); \node[below=0.2cm of item, align=center] \tiny partial key: item\_number \\ attributes: product\_name, quantity, price; \endtikzpicture \captionWeak Entity LINE ITEM identified by ORDER \endfigure \item \textbfPatient: patient\_id (PK), name, illness

% Optional: show as associative entity? For clarity, many-to-many with attribute. \endtikzpicture \captionERD for University Enrollment (Many-to-Many with attribute) \endfigure \noindent\textitNote: In physical design, ENROLLS becomes a bridge table containing student\_ID, course\_code, and enrollment\_date.

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% Better to use explicit relationship diamond for clarity \endtikzpicture \endfigure \noindent Alternative clear diagram: \beginfigure[H] \centering \begintikzpicture \node[rectangle, draw] (dept) DEPARTMENT; \node[rectangle, draw, below=2cm of dept] (emp) EMPLOYEE; \node[diamond, draw, left=1cm of dept] (works) WORKS\_IN; \node[diamond, draw, right=1cm of dept] (manages) MANAGES;