Bài giảng Hệ cơ sở dữ liệu - Chương 1: Giới thiệu về cơ sở dữ liệu

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Bài giảng Hệ cơ sở dữ liệu - Chương 1: Giới thiệu về cơ sở dữ liệu CHAPTER 1 Giảng viên: Trần Thị Kim Chi 1 1 What is a Database 2 What is Database Management System 3 Introduction SQL Server 4 SQL Server Services & Tools 5 Introduction about SQL Server 2008 6 SQL Server 2008 Database - Object 7 Questions 2 1 Data and Information Data (dữ liệu) và information (thông tin) • Data is raw, unorganized facts that need to be processed. Data are any facts, numbers, or text that can be processed by a computer. • Information – When data is processed, organized, structured or presented in a given context so as to make it useful, it is called information DỮ LIỆU THÔNG TIN XỬ LÝ (DATA) (INFORMATION) 3 1 Data and Information Data (dữ liệu) và information (thông tin) Dữ liệu 1 10273 Nguyễn Văn Hoà CDTH7 20 2 00298 Nguyễn Minh Tâm CDTH7 19 … 151 50542 Hồ Xuân Phương TCTH33 18 152 50075 Lê Việt Dũng CNTH34 20 Thông tin: dữ liệu trong ngữ cảnh STT Mã sinh viên Họ và tên sinh viên Lớp Tuổi 1 10273 Nguyễn Văn Hoà CDTH7 20 2 00298 Nguyễn Minh Tâm CDTH7 19 … 151 50542 Hồ Xuân Phương TCTH33 18 152 50075 Lê Việt Dũng CNTH34 20 4 1 Data Model  A data model is a “description” of both a container for data and a methodology for storing and retrieving data from container.  Data model is  Not a thing  You cannot touch it  Data model are abstractions, mathematical algorithms & Concepts. 5 1 What is a Database • A database a set of data that has a regular structure and that is organized in such a way that a computer can easily find the desired information. Application Program 1 Database Application Program 2 Application Programs Users 6 1 Database System Model Database management systems follow particular models (known as database models) to store and manipulate data. A database model is characterized by: 1. The way it stores data : STRUCTURE 2. The way data in the structure are manipulated: OPERATIONS 7 1 Characteristics of the Datatabase • Persistent: – Should be able to store all kinds of data that exists in this real world. • Interrelated: – Data and application should be isolated. – Should be able to relate the entities / tables in the database by means of a relation. i.e.; any two tables should be related. • Shared: – Multiple users should be able to access the same database, without affecting the other user. – Database should also provide security, – Database should also support ACID property. i.e.; while performing any transactions like insert, update and delete, database makes sure that the real purpose of the data is not lost. 8 1 Database Design  Objective  Ensuring data completeness  Avoiding data redundancies  Facilitating data access  Solution  Normalization • Reducing redundancies and improving data modification performance • Renormalizations is often done to enhance reporting performance (at the expense of disk space and redundancy)  Referential Integrity • Maintains the logical relationships between database objects 9 1 Steps in Database Design  Requirement analysis What does the user want?  Conceptual database design Defining the entities and attributes, and the relationships between these The ER model  Physical database design Implementation of the conceptual design using a Database Management System 10 1 ER model & Relational Data Model Relational Database Entities: Student (Id, Name, Suburb) Subject (No, Name, Dept) Student Id Name Suburb Takes 1108 Robert Kew SID SNO Relationships: 3936 Glen Bundoora 1108 21 8507 Norman Bundoora 1108 23 Student 8452 Mary Balwyn 8507 23 8507 29 Subject No Name Dept Takes 21 Systems CSCE 23 Database CSCE 29 VB CSCE Subject 18 Algebra Maths ER models view the world by entities and relationships Relational models view the world by relations 1 ER model & Relational Data Model Entities Tables Attributes ...