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• File Systems


  The method of organizing and retrieving files from a storage medium (hard drives, flash drives, CDs, etc.)
• File Systems


  Used by personnel in any organization to track and monitor necessary data
• Disadvantages of Using File Systems

  • Lengthy development times mean that even the simplest data-retrieval tasks require extensive programming
  • Report generation and query processing may be slow as it may require extensive programming on some languages, meaning it may take weeks or even months to generate reports from large amounts of data
  • System administration is complex, as report programs are created for each reporting need. As file numbers expand, administration becomes more difficult
  • Security and data sharing may present issues, as the sharing of files between users invites a lot of security risks that can cause damage to important data
  • Programming the systems may be too extensive, because of the various processes that need to be undertaken by the programmer to transfer a file structure into this form. This also means high costs, restricted access to data, and long development times
• Database Systems


  An organization of components that define and regulate the collection, storage, management, and use of data within a database environment
• Database Systems


  Computerized systems whose overall purpose is to maintain information and make that information available on demand
• Database


  A collection of both end-user data and metadata
• Metadata


  Self-describing data that contains characteristics and relationships that link the data found within the database itself
• End-user Data


  Raw facts of interest relevant to the end-user using the database
• Databases present a more complete depiction of data
• Databases basically work in a similar way as a typical file cabinet does
• Five Major Parts of a Database System

  • Hardware
  • Software
  • Peopleware
  • Procedures
  • Data
• Hardware


  All the system's physical devices, e.g. the computer and all other peripherals that control computer input and output
• Software


  • refers to the collection of programs used by the computers within the database
• OS (Operating System) Software


  The program that manages the hardware components which makes all other software run on a computer
• DBMS Software


  The software that manages the database within the database system
• Application Programs


  Mostly used to access and manipulate data in the DBMS, as well as manage the application environment (interfaces, menus, etc.) where data is accessed and manipulated
• Peopleware

  • System Administrators
  • Database Administrators (DBAs)
  • Database Designers and Architects
  • System Analysts and Programmers
  • End Users
• Procedures


  The rules that govern the design and use of the database system by enforcing standards on how the business will be conducted within the organization. They are mostly used to ensure monitoring and audit of both the flow of data and how it is organized within the database to maintain integrity.
• Data


  The collection of information, their relations and characteristics, within the database system
• Two Categories of Database Models

  • Conceptual Model
  • Implementation Model
• Conceptual Model


  Focuses on the logical nature of the data representation. It is concerned with what is represented in the database.
• Implementation Model


  Places emphasis on how the data are represented in the database or how the data structures are implemented to represent what is modeled.
• Building Blocks of a Database Model

  • Entities
  • Attributes
  • Relationships
  • Constraints
• Entities


  Anything about which data are to be collected and stored, such as a person, a place, a thing, or an event. It represents a particular kind of object in the real world that may either be a physical or conceptual object.
• Attributes


  The defining and/or important characteristics of an entity.
• Types of Relationships


  • One-to-One Relationships (1:1)
  • One-to-Many Relationships (1:*)
  • Many-to-Many Relationships (*:*)
• Constraints


  Restrictions placed on the data in order to ensure data integrity. They are usually written in the form of rules.
• Types of Database Models

  • Hierarchical Database Model
  • Network Model
  • Relational Model
  • Entity-Relationship Model
  • Object-Oriented Model
• Database Management Systems (DBMS)


  Part of the database system that manages the database structure and controls access to the data stored in the database
• Functions of a DBMS

  • Data dictionary management
  • Data storage management
  • Data transformation and presentation
  • Security management
  • Access control for multiple users
  • Backup and recovery
  • Data integrity management
  • Data access via query language
  • Communication interfaces and routines
• Data Dictionaries


  Centralized repositories of information about data such as meaning, relationships to other data, origin, usage, and format
• Two Main Types of Data Dictionaries

  • Integrated Data Dictionaries
  • Standalone Data Dictionaries
• Two Classifications of Data Dictionaries

  • Active Data Dictionaries
  • Passive Data Dictionaries
• SQL


  Structured Query Language, a database sublanguage used in querying, updating, and managing relational databases
• Major Components of SQL

  • Data Manipulation Language (DML)
  • Data Definition Language (DDL)
  • Data Control Language (DCL)
• Database Manipulation


  • CREATE DATABASE statement
  • DROP DATABASE statement
• Basic Data Retrieval


  • CREATE TABLE statement
  • ALTER TABLE statement
  • DROP TABLE statement
• Basic SQL Expression Clauses

  • SELECT clause
  • FROM clause
  • WHERE clause
• Aggregation


  A common programming term associated with the various methods in summarizing data, meaning to "combine into groups"
• Aggregation allows data to be manipulated into something that is not merely displayed, transforming data into "real" information: the pattern or context that is used as a requirement in order to transform data into something relevant