Review:
- IBM’s BSP
- functions, processes, activities
- tools: 2D matrices
- CSF
- identify “GOAL”
- critical factors that are essential to meeting objectives
- find variables underlie these decisions, and how to measure
- what information system can supply for these measure?
- E/M Analysis
- Ends: system’s goal
- Means: how to archive this goal
- how to measure
- Mix CSF and E/M analysis
- find out “GOAL”, defined critical success factor to objectives
- find variables under objectives
- using Means Specifications to migrate those variables into input and process
- using efficiency measures and effectiveness measure to evaluate means specifications
Today’s topic Chapter 3
- 需求階段可分成
- user requirement: not very structure
- user illustration
- system requirement: structure
- 三種需求 by science and engineering approach
- 資訊需求：data, reports
- 功能需求：一般如增、刪、修、查詢；資安功能需求…等
- 作業需求：一系列的界面設計(網頁編排，I/O)與流程安排，提供給使用者操作。本作業需求必需支援組織流程。system operations.
- logical independence = program-data independence
政大資管所一定會考
- 最小資料法則：所有需要的(資料)都已(被資料庫定義)包含，所有(被資料庫定義)包含的都是(拿來資料系統使用)需要的。而且需要被驗證。
- ER 出來的表，最少是 3rd 正規化的結果
- 使用 user requirements 來 verify E-R diagram
- Business rules 如何在 E-R Diagram 中表現? using cardinality!
- composite entity 是 E-R Diagram 掌控重心
- 在 n:m 的實作，是以雙向的 1:n 來表現，中間是 composite entity
- professor -> “teaches” -> class, connectivity 1:n, cardinality, 圈是 optional 可有可無
- 上述的就是 cardinality
