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• Chapter 1 introduces the concept of modern database systems.
• This chapter covers the difference between data and information, and the evolution of modern databases from file systems.
• This chapter also explains what components and functions make up a database system.
• Bicol University College of Science's Computer Science and Information Technology Department offers the CS105 - Information Management 1 course.

Objectives

• Understand the difference between data and information.
• Define and describe databases, their types, and their value in decision-making.
• Recognize the importance of database design.
• Know how modern databases evolved from file systems.
• Learn about flaws in file system data management.
• Identify the main components of a database system.
• Learn the main functions of database management.

Importance of Databases

• Businesses must keep different kinds of data for decision-making.
• Business information systems help businesses use information as an organizational resource.
• Databases are specialized structures for storing, managing, and retrieving data in computer-based systems.
• It is essential for information systems professionals to understand database structures.

Why Databases?

• Databases solve many problems associated with data management in modern settings.
• Settings include business, research, and administration.
• It is important to understand how databases work and interact with other applications.

Data vs. Information

• Data consists of raw facts.
• Information is derived from processing raw data to reveal its meaning.
• Information needs context to be meaningful.
• Data must be formatted for storage, processing, and presentation.
• Data forms the foundation of information, which is essential for knowledge.
• Data are building blocks of information.
• Information is produced by processing data and reveals meaning in data.
• Accurate, relevant, and timely information is critical for good decision-making.
• Good decision-making is essential to organizational survival.
• Data management focuses on proper generation, storage, and retrieval of data.

Introducing the Database

• A database is a shared, integrated computer structure that stores a collection including end-user data, and metadata.
• End-user data refers to raw facts of interest to the end user.
• Metadata refers to "data about data".
• Metadata provides a description of data characteristics and relationships and complements and expands the value of data.
• A database management system (DBMS) is a collection of programs that manages the database structure and controls access to the data.

File-Based System

• Information is stored in permanent computer files.
• New applications are added to the system as needed.
• A company system has multiple application programs that manipulate data files.

Basic File Terminology

• Data consists of raw facts like a telephone number, a customer name, or a year-to-date sales value.
• Meaning comes when there is an organized manner.
• A field is a character or group of characters with a specific meaning used to define and store data.
• A record is a logically connected set of one or more fields that describe a person, place, or thing.
• A file is a collection of related records.

Drawbacks of File System

• Data redundancy refers to the duplication of data.
• Redundancy leads to higher storage costs and poor access time.
• Data inconsistency arises from data redundancy when updates fail across all stored records.
• Data isolation occurs because data is scattered in various files with different formats, making data retrieval difficult.
• Dependency on application programs means changes in files require changes in application programs.
• Atomicity issues refer to the "all or nothing" principle, requiring all or none of the transaction operations to execute.
• Data security requires protection from unauthorized access, and security constraints are difficult to apply in file processing systems.

Structural and Data Dependence

• Structural dependence means access to a computer file depends on its structure.
• All file-system programs must be modified to conform to a new file structure.
• Structural independence means the file structure can change without affecting data access.
• Data dependence means data access changes when data storage characteristics change.
• Data independence means data storage characteristics do not affect data access.
• File systems exhibit both structural dependence and data dependence.
• Each program accessing a computer file needs to contain lines specifying file type, record specification, and field definitions.

Data Redundancy

• File system structure complicates combining data from multiple sources and is vulnerable to security breaches.
• Organizational structure promotes storage of same data in different locations.
• This creates islands of information.
• Data stored in different locations is unlikely to be updated consistently.
• Data redundancy means the same data is stored unnecessarily in different places.
• Data inconsistency means different and conflicting versions of same data exist in different places.
• Data anomalies are abnormalities that occur during updates, insertions, or deletions.

Example of Data Anomaly

• With an update anomaly, an agent's new phone number must be changed across all records.
• With an insertion anomaly, a new agent would have to be entered with a dummy customer.
• With deletion anomalies, deleting a customer may delete the only record of an agent.

Database

• A database is a shared, integrated computer structure that stores a collection of raw facts of interest to the end user.
• Metadata, or data about data, integrates and manages the end-user data.
• Database properties include the representation of real-world information and logical coherence and internal consistencey.
• Databases are often designed, built and populated with data for a specific purpose, and each data item is stored in a field and a combination of fields defines a table.

Database Systems

• A database system consists of logically related data stored in a single logical data repository that may be physically distributed.
• Database management systems eliminate most file system problems.
• Current generation systems store data structures and relationship & access paths, including defining, storing, and managing all access paths and components.

The Database System Environment

• The database system defines and regulates the collection, storage, management, and use of computer data
• A database system consists of hardware, software, people, procedures, and data.
• Hardware includes all physical devices.
• Software includes the operating system, the DBMS and the application/utility software.
• People include the administrators, designers, analysts, programmers, and end users.
• Procedures are the instructions and rules that govern design and use and data is the facts stored in the database.
• Database systems are managed at varying degrees of complexity, and database solutions must be cost-effective as wekk as tactically and strategically effective.

Role and Advantages of the DBMS

• A DBMS is a collection of programs that enables users to create and maintain databases and control all database access.
• A DBMS intermediates between the logical user and the physical storage.
• It also stores the database structure as a file collection and only allows file access through the DBMS.
• A DBMS integrates many users' views of the data enabling data sharing.

Advantages of a DBMS

• Improved data sharing
• Improved data security
• Better data integration
• Minimized data inconsistency
• Improved data access
• Improved decision making
• Increased end-user productivity

Types of Databases

• Databases can be classified according to the number of users, database location, and type and extent of use.
• A single-user database supports one user at a time and is also known as a desktop database which runs on a PC.
• A multi user database supports multiple users at the same time includeing work group and enterprise databases.
• A centralized database has data located at a single site.

Additional Classifications for Databases

• A distributed database has computer data distributed across several different locations.
• An operational database supports a company's day-to-day operations.
• This can also be referred to as a transactional or production database.
• A data warehouse stores data used for tactical or strategic decisions.

Data Formats

• Unstructured data exists in its original state.
• Structured data are formatted for storage and processing.
• Semistructured data have been processed to some extent.
• Extensible Markup Language (XML) represents textual computer data elements and is supported by XML databases.

Why Database Design Is Important

• Database design focuses on designing the database structure for end-user data.
• The designer must identify the database's expected use.
• A well-designed database facilitates data management and generates accurate and valuable information.
• A poorly designed database creates difficult-to-trace errors.

DBMS Functions

• DBMS functions guarantee data integrity and consistency.
• The data dictionary manages definitions of the data elements and their relationships (metadata) and records changes within such.
• DBMS provides computer data abstraction, and it removes structural and data dependence from the system.
• Data storage management creates and manages complex structures for data storage, including related data entry forms, screen definitions, and report definitions.
• Performance tuning enhances database efficiency.
• The DBMS stores the computer database in multiple physical data files.
• Data transformation and presentation convert computer data to required structures and user expectations.

Additional DBMS Functions

• Security management creates a security system that enforces user security and data privacy, including access rules.
• Multiuser access control uses algorithms to ensure concurrent access does not affect integrity.
• Backup and recovery management provides procedures to ensure data safety and integrity, including recovery after failure.
• Data integrity management promotes and enforces integrity rules, minimizes computer data redundancy, and maximizes consistency.

Structural Query Language

• Database access languages and application programming interfaces provide access through a query language.
• This is typically a structured query language (SQL)
• The SQL standard is supported by the majority of vendors.
• Database communication interfaces enable access via multiple different network environments.

Limitations

• Most users lack the skill to properly design databases.
• Developing data-modeling skills is vital in the computer data design process.
• Good data modeling facilitates communication between the designer, the user, and the developer.

Transaction Processing Systems

• Transaction processing systems are the systems that support the processing of "production" data such as accounting functions.
• Management information systems are used primarily by middle management to control the organization.
• Data is summarized and abstracted from transaction processing systems, and generates standard reports on periodic schedules.
• Decision support systems provide information for data managerial decision making, often using mathematical and statistical techniques.

DBMS Applications

• Common DBMS applications include:
  • Telecom
  • Industry
  • Banking system
  • Sales
  • Airlines
  • Education
  • Online shopping

Database Career Opportunities

• Opportunities exist in:
  • Database development
  • Database design
  • Database administration
  • Database analysis
  • Database architecture
  • Database consulting
  • Database security