1 / 16

Chapter 1 Introduction

Chapter 1 Introduction. Yonsei University 1 st Semester, 2014 Sanghyun Park. Database Management System (DBMS). Collection of interrelated data Set of programs to access the data DBMS contains information about a particular enterprise

kristen-clossick
Download Presentation

Chapter 1 Introduction

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 1Introduction Yonsei University 1st Semester, 2014 Sanghyun Park

  2. Database Management System (DBMS) • Collection of interrelated data • Set of programs to access the data • DBMS contains information about a particular enterprise • DBMS provides an environment that is both convenient and efficient to use • Databases touch all aspects of our lives

  3. Purpose of Database System • In the early days, database applications were built on top of file systems • Drawbacks of using file systems to store data: • Data redundancy and inconsistency • Difficulty in accessing data • Integrity problems • Atomicity of updates • Concurrent access by multiple users • Security problems • DBMS offers solutions to all the above problems

  4. View of Data • An architecture for a database system

  5. Data Models • A collection of tools for describing • Data • Data relationships • Data semantics • Data constraints • Entity-Relationship model • Relational model • Other models: • Object-oriented model, semi-structured data models • Older models: network model and hierarchical model

  6. Entity-Relationship Data Model

  7. Relational Model

  8. Data Definition Language (DDL) • Language for defining the database structure create table instructor (ID char(5),name varchar(20), dept_name varchar(20), salary numeric(8,2) ) • Execution of the above DDL statement creates the instructor table • In addition, it updates a special set of tables called the data dictionary

  9. Data Manipulation Language (DML) • Language for accessing and manipulating the data organized by the appropriate data model • Procedural DMLs require a user to specify what data are needed and how to get those data • Declarative (or Nonprocedural) DMLs require a user to specify what data are needed without specifying how to get those data • It is common to use the terms query language and data manipulation language synonymously • SQL is the most widely used query language

  10. Database Access From Applications • Application programs are programs that are used to interact with the database • Application programs are usually written in a host language, such as Cobol, C, C++, or Java • Application programs generally access databases through one of: • Language extensions to allow embedded SQL • Application program interface (e.g., ODBC/JDBC) which allows SQL queries to be sent to a database

  11. Application Architecture • Two-tier architecture: E.g. client programs using ODBC/JDBC to communicate with a database • Three-tier architecture: E.g. web-based applications

  12. Overall Database System Structure

  13. Storage Management • A program module that provides the interface between low-level data stored in the database and application programs and queries submitted to the system • Issues • Storage access • File organization • Indexing and hashing

  14. Query Processing • Parsing and translation • Optimization • Evaluation

  15. History of Database Systems (1/2) • Late 1960s and 1970s • Network and hierarchical data models in widespread use • Ted Codd defines the relational data model(Win the ACM Turing Award for this work)(IBM Research begins System R prototype)(UC Berkeley begins Ingres prototype) • 1980s • Research relational prototypes evolve into commercial systems(SQL becomes industrial standard) • Parallel and distributed database systems • Object-oriented database systems

  16. History of Database Systems (2/2) • 1990s • Large decision support and data-mining applications • Large multi-terabyte data warehouses • Emergence of Web commerce • 2000s • XML and XQuery standards • Automated database administration

More Related