unit8 Joint Data and Functional Analysis.pptVIP

Unit 8 Unit 8 Joint Data and Functional Analysis 本單元目的 交替改善 D-Schema 與 F-Schema 以得出一組完整的資料分析與功能分析的結果 D-Schema 即 conceptual schema, 是用 ER model 繪出之資料分析結果. F-Schema 即功能分析的結果, 是用 DFD 繪出的結果. 在同一應用系統中表現資料的 ER diagram 和 表現功能的 DFD 要相互參照. 在 DFD 中的 data store, 在 ER diagram 應進一步描述之. ER diagram 中出現的資料, 在 DFD 內某些 process 必處理之. Outline External Schema for Dataflow Diagram A Methodology for Joint Data and Functional Analysis Navigation Schemas for Database Operations External Schema for DFD External schema 是指某使用者看到的部分資料庫之資料架構圖, 也就是 conceptual schema 的 一部份. 每個 application program 有不同的 external schema. An example of external schema A Methodology for Joint Data and Functional Analysis Step 1 繪出 context diagram Step 2 繪出 D-Schema 及 F-Schema 的初步架構圖 Step 3 重複相互參照改善工作, 直到充分表達需求 Step 3.1 參照 F-Schema, 改進前一版的 D-Schema Step 3.2 參照 D-Schema, 改進前一版的 F-Schema Step 3.3 檢查 D-Schema 與 F-Schema 的相互一致性 Step 4 檢查 F-Schema 及 D-Schema 的品質 An Example: Student Information System Requirements: The registers office of a university maintains information concerning each students study plan, indicating the courses that students have taken or will take; when each course is completed, the information about the final grade and the date of completion is also recorded. For Ph.D. students, the department maintains the names of advisors and the title and date of the qualifying examination. This information is modified when the student presents the study plan for the subsequent term, when professors return the grades at the end of the term, and when Ph.D. students select their advisors or define their Ph.D. qualifying examinations. Students may request reports concerning their grades or Ph.D. progress. Completeness check Navigation Schemas for Database Operations Database operations 指對資料庫存取資料或更新資料的動作,是和資料庫交談的基本單元, 是 process 動作的一部份. 例如一個 SQL 查詢, 即為一個Database Operation. Navigation Schema 指引一個 database operation 搜尋資料時所經過的路徑 在 logical database design 時用到 每個 database operation 可以繪出一個 navigation schema Exampl