An Overview of Database

database
공개

2024년 9월 3일

The Importance of DBs Today

  • Depend upon database: Internet, Web 2.0, IOT

Why and How Databases are Used?

  • The purpose of a database is to keep track of thing
  • db store information that is more complicated than a simple spread sheet

Problems with Lists (spread sheet)

  1. Redundancy

필요없는 column들이 중복됨
  1. Multiple Themes
  • 그 결과로, list에 나타날 때만 존재하는 informartion이 생김
  1. List Modification Issues

deletion problems, update problems, insertion problems

Relational Databases

  • Relationa Model is methodology used as a solution for database design
  • A relational database stores information in tables
    • Each informational topic is stored in its own table
  • Each theme in the list can be stored in a table

Table = file = relation
column = fields = attribute
row = record = tuple

SQL (Structured Query Language)

  • international standard for creating, processing, querying databases and their tables
  • db applications use SQL to retrieve, format, report, insert, delete, modify data for users
  • can combine table by join operation
SELECT  CUSTOMER.CustomerLastName, 
        CUSTOMER.CustomerFirstName, 
        CUSTOMER.Phone,
        COURSE.CourseDate, 
        ENROLLMENT.AmountPaid,
        COURSE.Course, 
        COURSE.Fee
FROM    CUSTOMER, ENROLLMENT, COURSE
WHERE   CUSTOMER.CustomerNumber = ENROLLMENT.CustomerNumber -- join condition
        AND  COURSE.CourseNumber = ENROLLMENT.CourseNumber; -- join condition

Database System (DBS)

The four components of database system
  • User: Employ database application to keep track of things
    Use forms to read, enter, query data
    produce reports
  • Database Application: web/mobile database applications, Forms, Reports
  • DBMS: used to create, process, administer the database
  • Database: self-describing collection of related tables
    user data, metadata, index and other overhead data, application metadata(form, reports) are stored in db
    metadata = about the structure of the database. <-> user data

Function of DBMS

  • DB administration
    • Control concurrency
    • Provide security
    • Perform backup and recovery

Referential Integrity Constraints

Personal vs Enterprise-class Database Systems

  • Personal: Access
  • Enterprise-class(Organizational): Microsoft SQL server

NoSQL databases

  • NoSQL database = non-relational database

Cloud databases

Main frame -> Client/server -> Cloud

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