📚 Year 12 Cambridge Computer Science: Mastering Case Studies | Year 12 剑桥计算机：案例分析实战演练
Case study questions are a core component of the Cambridge International AS & A Level Computer Science (9618) assessment, challenging you to apply theory to realistic systems. In this article, we walk through a practical case study — a smart school library system — to show you how to analyse, design, and evaluate effectively, giving you the skills to earn top marks.
案例分析题目是剑桥国际 AS & A Level 计算机科学（9618）考试的重要组成部分，要求你将理论知识应用到真实系统中。本文通过一个实际案例研究——智能校园图书馆系统——来演示如何有效地进行分析、设计和评估，帮助你掌握获得高分的技能。
1. Understanding the Case Study Scenario | 理解案例研究情景
Always begin by reading the pre‑release material thoroughly. In our 'SmartLibrary' case, the school wants a web‑based system that tracks book loans, manages student accounts, calculates overdue fines automatically, and allows self‑service check‑out via RFID tags. A reporting dashboard for librarians is also required.
始终从仔细阅读预发布材料开始。在我们的 'SmartLibrary' 案例中，学校需要一个基于网络的系统，能够跟踪图书借阅、管理学生账户、自动计算逾期罚款，并可通过 RFID 标签实现自助借还。此外，还需要为图书管理员提供报告仪表板。
2. Identifying Functional Requirements | 识别功能性需求
Functional requirements describe what the system must do. For SmartLibrary, they include searching the catalogue, borrowing and returning books, sending email reminders, computing fines, and generating usage reports by genre or year group. Capture these as an itemised list to ensure no feature is missed.
功能性需求描述了系统必须做的事情。对于 SmartLibrary，它们包括搜索图书目录、借还与归还图书、发送电子邮件提醒、计算罚款，以及按类别或年级生成使用报告。将这些需求逐项列出，可以确保不遗漏任何功能。
3. Non-Functional Requirements & Constraints | 非功能性需求与约束
Non‑functional requirements define system quality attributes. The library system must support 500 concurrent users, respond within 2 seconds, ensure 99.9 % uptime during school hours, and comply with data protection regulations. Constraints include a limited budget, reliance on the school’s Wi‑Fi, and integration with the existing student database.
非功能性需求定义了系统的质量属性。图书馆系统必须支持 500 名并发用户，在 2 秒内响应，确保在校期间 99.9% 的正常运行时间，并遵守数据保护法规。约束条件包括有限的预算、依赖学校 Wi-Fi，以及与现有学生数据库的集成。
4. Stakeholder Analysis | 干系人分析
Identify all stakeholders and their interests. Students want a quick, mobile‑friendly search and fine‑free reminders. Librarians need detailed circulation reports and an intuitive dashboard. IT staff require secure API endpoints and easy maintenance. School governors focus on cost‑effectiveness. Documenting these needs helps prioritise development.
识别所有干系人及其关注点。学生希望快速、适合移动设备的搜索和无罚款提醒。图书管理员需要详细的流通报告和直观的仪表板。IT 人员要求安全的 API 接口和易于维护。学校管理层关注成本效益。记录这些需求有助于确定开发优先级。
5. Data Modelling: Key Entities and Relationships | 数据建模：关键实体与关系
From the requirements, extract entities and attributes. A sensible design might include Student, Book, Loan, Fine, and Reservation tables. The relationships are straightforward: a Student borrows many Books via Loan; each Loan can generate a Fine. The table below summarises core fields.
从需求中提取实体和属性。合理的设计可能包括 Student、Book、Loan、Fine 和 Reservation 表。关系很简单：Student 通过 Loan 借阅多本 Book；每条 Loan 可以产生一个 Fine。下表总结了核心字段。
| Entity | Key Attributes |
|---|---|
| Student | StudentID (PK), Name, Email, YearGroup |
| Book | ISBN (PK), Title, Author, Genre, Status |
| Loan | LoanID (PK), StudentID (FK), ISBN (FK), DateOut, DateDue, DateReturned |
| Fine | FineID (PK), LoanID (FK), Amount, Paid |
（表）核心实体及其属性。PK 表示主键，FK 表示外键。
6. Process Design: Flowcharts and Pseudocode | 流程设计：流程图与伪代码
Break down the borrowing process into steps: check student membership, verify book availability, create a loan record, update book status, and issue a due date. Represent this as a flowchart with decision diamonds for membership and availability. Pseudocode helps clarify logic before coding.
将借阅流程分解为步骤：检查学生会员资格、验证图书可用性、创建借阅记录、更新图书状态并生成到期日期。用带有判断菱形（会员资格和可用性）的流程图来表示。伪代码有助于在编码前理清逻辑。
PROCEDURE borrowBook(studentID, ISBN)
IF NOT validMember(studentID) THEN RETURN 'Invalid member'
ENDIF
IF bookStatus(ISBN) ≠ 'Available' THEN RETURN 'Book unavailable'
ENDIF
dueDate ← TODAY + loanPeriod
INSERT INTO Loan VALUES (studentID, ISBN, TODAY, dueDate, NULL)
UPDATE Book SET Status = 'OnLoan' WHERE ISBN = ISBN
RETURN 'Success'
ENDPROCEDURE
7. Algorithm Selection and Computational Thinking | 算法选择与计算思维
When designing features such as overdue fine calculation, you must choose the right algorithm. A simple linear search over loan records finds overdue items, but indexing Loan by DueDate can speed up daily batch processing. Discuss time complexity: the naive linear scan is O(n), while an indexed search can reduce it to O(log n). Explain why this matters when the system scales to thousands of loans.
在设计逾期罚款计算等功能时，你必须选择合适的算法。简单的线性搜索可以找到逾期记录，但按 DueDate 为 Loan 建立索引可以加快每日批处理速度。讨论时间复杂度：简单的线性扫描是 O(n)，而索引搜索可降至 O(log n)。解释当系统扩展至数千条借阅记录时，这一点为何重要。
8. User Interface and Output Design | 用户界面与输出设计
A well‑designed interface improves usability. For students, provide a clean search bar, a list of current loans with due dates, and a ‘Renew’ button. Colour‑code items (green for ‘returned on time’, red for ‘overdue’). Librarians need a dashboard with charts showing most‑borrowed genres and overdue trends. Always consider accessibility: high contrast, keyboard navigation, and screen reader support.
精心设计的界面可以提升可用性。为学生提供简洁的搜索栏、带有到期日期的当前借阅列表和'续借'按钮。用颜色编码项目（绿色表示'按时归还'，红色表示'逾期'）。图书管理员需要带有图表（显示最常借阅种类和逾期趋势）的仪表板。始终考虑无障碍性：高对比度、键盘导航和屏幕阅读器支持。
9. Testing Strategy: From Unit to Acceptance | 测试策略：从单元测试到验收测试
Describe a multi‑level testing plan. Unit tests check the fine calculation function with boundary values (0, 1, maximum loan days). Integration tests verify that the borrow procedure correctly updates both Loan and Book tables. System tests simulate 500 concurrent users borrowing at once. User acceptance testing (UAT) involves librarians and students navigating prototypes. Highlight the importance of test data that includes normal, extreme, and erroneous inputs.
描述多层次测试计划。单元测试使用边界值（0、1、最大借阅天数）检查罚款计算函数。集成测试验证借阅流程是否正确更新 Loan 和 Book 表。系统测试模拟 500 名并发用户同时借阅。用户验收测试（UAT）邀请图书管理员和学生操作原型。强调包含正常、极端和错误输入测试数据的重要性。
10. Security, Privacy and Ethical Considerations | 安全、隐私与伦理考量
Protecting student data is paramount. The system must hash passwords, use HTTPS for all traffic, and implement role‑based access control (students cannot view other students’ loan histories). The school must obtain consent for storing email addresses. Discuss ethical issues such as digital exclusion if some students lack smartphones for the mobile app, and propose a card‑based alternative at kiosks.
保护学生数据至关重要。系统必须对密码进行哈希处理，所有流量使用 HTTPS，并实施基于角色的访问控制（学生不能查看其他学生的借阅历史）。学校必须获得存储电子邮件地址的同意。讨论伦理问题，例如如果部分学生没有智能手机使用移动应用可能造成的数字排斥，并提出在自助终端上使用借书卡作为替代方案。
11. Implementation Example: Loan Fine Calculation | 实现示例：借阅罚款计算
To solidify your understanding, here is a more detailed pseudocode routine for fine computation. The daily fine rate is £0.10, and the library allows a 14‑day loan period. The algorithm returns the fine amount or zero.
为了巩固理解，下面给出更详细的罚款计算伪代码例程。每日罚款费率为 £0.10，图书馆允许借阅 14 天。该算法返回罚款金额或零。
FUNCTION calculateFine(dueDate, returnDate)
overdueDays ← (returnDate - dueDate)
IF overdueDays ≤ 0 THEN
RETURN 0
ELSE
fine ← overdueDays × 0.10
IF fine > maxFine THEN fine ← maxFine
ENDIF
RETURN fine
ENDIF
ENDFUNCTION
Edge cases include leap years and the maximum fine cap, which should be tested thoroughly. This exercise demonstrates how to translate a business rule into precise, testable logic.
边缘情况包括闰年和最高罚款上限，这些都应当彻底测试。这个练习展示了如何将业务规则转化为精确、可测试的逻辑。
12. Top Tips for Tackling Case Study Exams | 攻克案例分析考题的最佳技巧
Use the mark scheme to guide the depth of your answers. Always refer back to the scenario — generic answers lose marks. Structure responses with clear headings: Hardware/Software Requirements, Data Structures, Algorithms, Evaluation. Manage your time by spending 10 minutes planning before writing. Practice past papers repeatedly; there is no substitute for hands‑on experience.
利用评分方案指导答案的深度。始终回扣案例——泛泛而谈会丢分。用清晰的标题组织答案：硬件/软件需求、数据结构、算法、评估。合理安排时间，在写作前花 10 分钟规划。反复练习历年真题；实际动手经验无可替代。
Published by TutorHao | Computer Science Revision Series | aleveler.com
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