Introduction to Databases and DBMS

• The material covers fundamental database concepts
• The text defines what databases are
• The text explains the difference between data and information
• The text also explores the importance of database design

Data vs. Information

• Data are raw, unprocessed facts and serve as the building blocks of information
• Information results from processing data to reveal its meaning
• Accurate, relevant, and timely information is key for effective decision making
• Good decision making is essential for thriving in a global environment

Introducing Databases and DBMS

• A database represents a shared, integrated computer structure
• Databases store end-user data or raw facts
• Databases store metadata or data about data

DBMS (Database Management System) details

• DBMS refers to a collection of programs that manages database structure
• DBMS controls access to the data
• Sharing data among multiple applications and users is possible using DBMS
• DBMS improves the efficiency and effectiveness of data management
• The DBMS promotes an integrated view of an organization's operations which leads to reduced data inconsistency
• DBMS makes it easier to produce quick answers to ad hoc queries

Types of Databases

• Single-user databases support only one user at a time
• Desktop databases are single-user databases running on a personal computer
• Multi-user databases enable simultaneous access by multiple users
• Workgroup databases support a small group of users or a single department
• Enterprise databases support a large group of users or an entire organization
• Centralized databases have data located at a single site
• Distributed databases have data distributed across several sites
• Transactional, or production, databases support a company’s day-to-day operations
• Data warehouses store data used to generate information for tactical or strategic decisions
• Data warehouses often store historical data

Importance of Database Design

• Database design defines the database's expected use
• Designing different types of databases requires different approach
• Avoiding redundant data is critical
• Poorly designed databases lead to errors, bad decisions, and organizational failure

Manual File Systems

• Traditional manual file systems used file folders stored in file cabinets
• Folder organization was based on data use
• Manual systems were adequate for small data amounts with limited reporting needs
• However, manual systems became time-consuming and cumbersome when trying to find data in growing collections of file folders

Evolution to Computer File Systems

• Converting to computer file systems could be technically complex and required data processing specialists
• DP specialists create file structures, write software, and design application programs
• This conversion resulted in numerous "home-grown" systems being created
• Initially, computer files mirrored the design of manual files

Basic File Terminology

• Data is raw facts such as telephone numbers and customer names
• Data has little meaning until data is logically organized
• The smallest piece of data the computer recognizes is a single character requiring one byte of computer storage
• A field refers to a character or group of characters with a specific meaning
• A record is a logically connected set of one or more fields describing a person, place, or thing
• A file is a collection of related records and might contain data about vendors or enrolled students

Simple File System details

• As the number of databases increased, small file systems evolved
• Each file used its own application programs
• Each file was owned by the individual or the department that commissioned its creation
• An example of field definitions includes customer last name, customer first name, Customer initial etc.

Data Redundancy and Anomalies

• Data redundancy results in data inconsistency
• Different and conflicting versions of the same data appear in different places
• Errors are more likely with complex entries made in several files
• Data anomalies develop when required changes in redundant data are not successfully made
• Modification anomalies occur when changes must be made to existing records
• Insertion anomalies occur when entering new records
• Deletion anomalies occur when deleting records

Database vs. File System

• Database systems address problems inherent in file systems
• File systems consist of many separate and unrelated files
• A database is logically related data stored in a single data repository

The Database System Environment

• The database system has 5 main components
• Hardware
• Software including DBMS software, operating system software, and application programs
• People
• Procedures
• Data

DBMS Functions

• DBMS performs functions that guarantee data integrity and consistency
• Data dictionary management defines data elements and their relationships
• Data storage management stores data, data entry forms, and report definitions
• Data transformation and presentation translates logical requests into commands to locate and retrieve data
• Security management enforces user security and data privacy within the database
• Multi-user access control creates structures that allow multiple users to access the data
• Backup and recovery management provides backup and data recovery procedures
• Data integrity management promotes and enforces integrity rules
• Database access languages and application programming interfaces provide data access through a query language
• Database communication interfaces allow the database to accept end-user requests within a computer network environment