教案数据库rname 李霞De.pptxVIP

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教案数据库rname 李霞De.pptx

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Course lecturer;Course format/policies;Teaching material;Content of the course;Good works from grade 2009;Chapter 1: Introduction ;一 data, database, DBMS, DBS;data;database;database;Database Management System (DBMS);Database Management System (DBMS);Database system (DBS) ;a whole view to DB, DBMS, DBS;15;Purpose of DBS;In the early days, database applications were built directly on top of file systems But there many disadvantages in a file-processing systems. So , DBS is offer solutions to all the problems Now, let’s see those disadvantages in file systems. ;Drawbacks of using file systems to store data;Drawbacks of using file systems to store data;Drawbacks of using file systems to store data;Drawbacks of using file systems to store data;Database systems offer solutions to all the above problems;3 view of data;A DBS is a collection of interrelated data and a set of programs that allow users to access and modify these data. A major purpose of a DBS is to provide users with an abstract view of the data. That is, the system hides certain details of how the data are stored and maintained. ;Levels of Abstraction;View of Data;4 Instances and schemas;Instances and Schemas;Schema;Instances and Schemas;5 Data modes;Data Models;Relational Model;A Sample Relational Database;6 Database Language;Database Language;Data Manipulation Language (DML);Data Definition Language (DDL);Data Definition Language (DDL);SQL;Database access from application programs;7 database design ;Database Design;Database Design;Database Design?;Design Approaches;The Entity-Relationship Model;8 database architecture ;Database Architecture;database architecture;Database Users and Administrators;Database System Internals;9 History of Database Systems ;History of Database Systems;History (cont.);History (cont.);assignments