大连理工数据库1InTrodUCTion.pdf

Principles of Database Systems 1 Introduction 1 Basic Concepts 2 Basic Concepts  Data – Values of qualitative or quantitative variables, belonging to a set of items (wikipedia) – Data as an abstract concept can be viewed as the lowest level of abstraction from which information and then knowledge are derived (wikipedia) 3 Basic Concepts  Data – Does data always be useful? 4 Basic Concepts  Data – Does data always be useful? 5 Basic Concepts  Data – Data on its own carries no meaning. For data to become information, it must be interpreted （解 释）and take on a meaning. 6 Basic Concepts  Another Example – the height of Mt. Everest （珠穆朗玛峰）is generally considered as data – a book on Mt. Everest geological characteristics may be considered as information – a report containing practical information on the best way to reach Mt. Everests peak may be considered as knowledge. 8848.64 7 Basic Concepts  Database (DB) – Collection of interrelated （相互关联的）data 8 Basic Concepts  How to access and manage database? 9 Basic Concepts  Database Management System (DBMS) – a collection of interrelated data and a set of programs （程序）to access those data – An environment that is both convenient （方便的） and efficient （有效的）to use data – DBMS is the core of database systems. – Datab