CHAPTER 7資料庫管理系統.pptVIP

CHAPTER 7 資料庫管理系統 Data Base Management System 主題:?????????? 1. 資料庫之使用 2. 基本的資料庫觀念 3. 資料庫管理系統實作 4. 資料庫理論基礎 傳統檔案結構與資料庫之比較 1. Access Method (資料找尋方式) 2. Data Consistent (資料一致性) 3. 應用程式撰寫複雜 4. 資料格式不一致 Access Method (資料找尋方式) 傳統檔案----人工 Data base----自動 Data Consistent (資料一致性) 傳統檔案之缺點???? 1.Data Redundancy (資料重覆性)?????? Duplication of data items in different files.???? 2.檔案維護困難??????? update,insert,delete......,(Data Inconsistent) 3.應用程式撰寫複雜 ??a.每個查詢必須寫一個對應程式? b.資料查詢方式必須由程式控制 Data Consistent (資料一致性) 傳統檔案之缺點???? 4.資料格式不一致 a.某個item在不同檔案內，可能造成資 料型態不一致? b.Data Dependence???? File characteristics are changed, the application program must also be modified. Data Base Definition: 1.A Collection of interrelated data stored together? (一群相關資料集合) ? 2.With as little redundancy as possible (儘可能避免資料的重覆性) ? 3.To serve one or more applications in an optional fashion? ? Data Base Definition: 4.The Data are stored so that they are independent of programs which use the data, A common and controlled? approach is used in adding new data and in modifying and retrieving existing data within data base. 為什要使用資料庫: 1.減少資料重複性 ???? 2.避免資料不一致的情形發生 ???? 3.能夠共用資料 ???? 4.提供標準的使用工具?? Data Definition , Data Manipulation ????????????????????????????????? ???? 5.增加資料的私密性 ???? 6.維護資料之整體性?? (Integrity) ???? 7.資料的獨立性??? (Data Independent) ???? 8.資源共用及資料回復功能? (Concurrency and Recovery) ISAM file 與資料庫之異同點(Index Sequential Access Method) 1.File Record Layout Data Base System Architecture 1.Standard Storage Structure? = Access Method 2.Conceptual Schema (schema) =DBA 3.External Schema (subschema) =DBA or user? 4.Host Language + Data Base utilities Data Base Description Language 3.Data Manipulation?Language (DML) ???? A.Programming Language Extension (Embedded Statement) ???? B.Functional call ???? C.Query 資料庫管理系統作業步驟 * * 查詢:1. Find personal Name who graduated from Chung Yuan University‘ ???? ????2. Find Description of all manager ............... Brithday NAME ID