Database Systems: Evolution, Components, and Functions, Cheat Sheet of Database Programming

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Unit 1: Database

Systems

(Part 2)

In the Previous Class

• Introduction
• The difference between data and information
• What is a database?
• Database Management Systems
• Types of databases
• Database design

Outline

• RECAP!

• How modern databases evolved from file systems
• Problems with the computerized file system
• The Database system
• Components of the database system
• Functions of a database management system (DBMS)
• Disadvantages of a database system
• Database Career Opportunities

Recap

• Databases store o Data and ???

Recap

• What does DBMS stand for?

Recap

• Give Examples of database management systems (DBMS)

Recap

• What does SQL stand for?
• What is SQL used for?

Outline

• RECAP!

• How modern databases evolved from file systems
• Problems with the computerized file system
• The Database system
• Components of the database system
• Functions of a database management system (DBMS)
• Disadvantages of a database system
• Database Career Opportunities

Table 1.2 - Basic File Terminology

TERM DEFINITION Data Raw facts, such as a telephone number, a birth date, a customer name, and a year-to-date (YID) sales value. Data have little meaning unless they have been organized in some logical manner. Field A character or group of characters (alphabetic or numeric) that has a specific meaning. A field is used to define and store data. Record A logically connected set of one or more fields that describes a person, place, or thing. For example, the fields that constitute a record for a customer might consist of the customer's name, address, phone number, date of birth, credit limit, and unpaid balance. File A collection of related records. For example, a file might contain data about the students currently enrolled at Gigantic University.

An Example file from a file system

Exercise: An Example file from a file system

The CUSTOMER file contains 10 records. Each record is composed of 9 fields: C_NAME, C_PHONE, C_ADDRESS, C_ZIP, A_NAME, A_PHONE, TP, AMT, and REN.

Figure 1.8 - A Simple File System

Sales department Personnel department

Problems with File System Data Processing

• Data Redundancy
  • having many data files with overlappin data with.
• Complex system administration
  • no means of controlling or managing the data consistently across all of the files
• Lengthy development times
  • For data retrieval
• Difficulty of getting quick answers (quick reports)
• Lack of security; limited data sharing
  • Difficult to program; often omitted
• Extensive programming

Structural Dependence

Structural dependence : Access to a file is dependent on its own structure

• All file system programs are modified to conform to a new file structure Structural independence : File structure is changed without affecting the application’s ability to access the data