Exercises And Answers Pdf — Entity-relationship Diagram

\textbfNotation: We use \textbfCrow's Foot notation. \beginitemize \item Entities: Rectangles \item Primary Key: Underlined attribute \item Relationships: Diamonds (or labeled lines) with crow's foot for many side. \item Cardinalities: 1 (one), M (many), (0,1) optional one, etc. \enditemize

\sectionExercise 2: Library System \textbfScenario: \\ A library wants to track books and members. \beginitemize \item \textbfBook: ISBN (unique), title, author, year. \item \textbfMember: member\_id (unique), name, phone. \item A member can borrow many books, but a specific copy of a book can be borrowed by only one member at a time (simplified: assume one copy per ISBN). \item A book may be borrowed by many members over time. \item The relationship \textbfBorrows has attributes: borrow\_date, return\_date. \enditemize

% Lines \draw (student) -- (enroll) node[midway, left] M; \draw (course) -- (enroll) node[midway, right] M;

\titleEntity-Relationship Diagram (ERD) Exercises \\ with Answers \authorDatabase Design Workbook \date\today

\section*Appendix: Quick ERD Notation Reference \begintcolorbox \begintabularl \hline \textbfSymbol & \textbfMeaning \\ \hline Rectangle & Entity \\ Oval & Attribute (sometimes omitted, listed inside entity) \\ Diamond & Relationship \\ Underline & Primary Key \\ Double Rectangle & Weak Entity \\ Double Diamond & Identifying Relationship \\ 1 at line end & One cardinality \\ M or * at line end & Many cardinality \\ Circle (O) & Optional participation \\ \hline \endtabular \endtcolorbox

% Relationship \node[diamond, draw, aspect=2, minimum width=2cm, minimum height=1cm, below=1.2cm of $(student.south)!0.5!(course.south)$] (enroll) ENROLLS; \node[below=0.2cm of enroll, align=center] \tiny enrollment\_date;

\textbfTask: Draw the ERD showing: \beginitemize \item One-to-Many relationship between Department and Employee (works-in). \item One-to-One relationship between Employee and Department (manages). \item Indicate mandatory/optional participation. \enditemize

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