Database Models and Object-Oriented Data

Unit 4: Data Resource Management and DSS

• This unit covers Data Resource Management and Decision Support Systems (DSS).
• Topics include fundamental data concepts, database structures, database development, types of databases, and the technical foundation of database management.
• The outcomes for the unit include understanding key data concepts, proficiency in database structures, and knowledge of database models.

Fundamental Data Concepts

• Data is handled by software called database management systems (DBMS).

• DBMS facilitate data organization, manipulation, retrieval, and management within a database.

• Data, including formats, field names, record, and file structures, is managed.

• Rules are set for data validation and interaction.

• Fourth-generation query languages (e.g., SQL) are frequently used, interacting with DBMS packages for database management.

• A conceptual framework details multiple data levels, logically organizing data into characters, fields, records, files, and databases.

• Logical list of data elements:

  • Characters
  • Fields
  • Records
  • Files
  • Databases

• Characters: The basic logical data element (alphabetic, numeric, symbols).

• Fields: A grouping of characters, attributes of an entity (employee name, salary).

• Records: Group of fields describing an entity instance (one employee's attributes).

• Files: Groups of related records (a file of employee records).

• Databases: An integrated group of files or tables (a company's entire data).

Outcomes

• Understanding key data concepts enables efficient database design and management
• Proficiency in database structures such as tables, tuples, attributes, and keys facilitates effective data organization and retrieval.
• Knowledge of database models like hierarchical, network, and relational databases allows for database design tailored to specific needs.

Limitations of File Processing Systems

• Unfriendly interface
• High data redundancy and inconsistency
• Difficulty in accessing data
• Concurrent access problems
• Integrity problems
• Atomicity problems
• Security issues
• Data is often unshareable, and recovering from corrupt data is difficult
• Backup procedures are often laborious

Applications of Databases

• Banking: customer accounts, transactions, financial data
• Airlines: flight schedules, reservations, customer details
• Universities: student information, course schedules
• Sales: customer details, sales figures
• Online retailers: product info, customer orders
• Human Resources: employee data, payroll details

Database Management Systems (DBMS)

• DBMS are software systems for creating, modifying, and managing databases.
• DBMS manage interrelated data and programs for accessing that data.
• DBMS provide a means of storing, retrieving, and manipulating structured data systematically.
• The primary goal is convenient and efficient database information access.
• Examples include MySQL, Oracle Database, SQL Server, MS Access, and SQLite.

Components of DBMS

• Hardware: The physical infrastructure supporting the system.
• Software: The programs enabling database operations.
• Data: The information stored and managed.
• Data Access Language: A language for writing commands to interact with data (e.g., SQL).
• Procedure: A set of instructions that guides the use of the DBMS (database setup, management, backup procedures).

SQL Commands

• Divided into categories: Data Definition Language (DDL), Data Manipulation Language (DML), Data Control Language (DCL), Data Query Language (DQL), Transaction Control Language (TCL)
• Commands used to manage data (create, insert, update, delete, select, commit, rollback, grant, revoke).

Functions of DBMS

• Data Storage, Retrieval, and Update: Facilitates efficient data handling and access.
• Data Organization and Management: Organizes data into tables, schemas, and maintains metadata.
• Transaction Management: Ensures ACID properties (Atomicity, Consistency, Isolation, Durability) for transaction integrity and reliability.
• Concurrency Control: Supports simultaneous access from multiple users, preventing deadlocks and inconsistencies.
• Data Integrity: Enforces rules for accuracy and consistency.
• Data Security: Protects data from unauthorized access.

DBMS Advantages and Disadvantages (Assignment Topic)

• Advantages:

  • Data integration and sharing.
  • Reduced data redundancy.
  • Improved data consistency.
  • Enhanced data security and integrity.
  • Efficient data retrieval.
  • Support for data integrity rules.

• Disadvantages:

  • Increased system complexity.
  • Higher cost in hardware and software.
  • Potential data dependency between different parts of the database.
  • Complexity in training and maintenance.
  • Potential for data loss if the database becomes corrupted or damaged.

Database Structures (Models)

• Database structures dictate how data is organized, stored, accessed, and managed.
• Common structures: Hierarchical, Network, Relational, Object-Oriented, ER Model.
  • Each offers unique approaches to modeling data and relationships.

Hierarchical Model (characteristics)

• One of the oldest database models.
• Data organized in a tree-like fashion.
• Data stored hierarchically (top-down or bottom-up).
• Data represented using parent-child relationships.
• Each parent can have many children, but each child has only one parent.

Network Model

• An advanced version of the hierarchical model.
• Data is represented as a graph.
• Each child can have multiple parents.
• It addresses the need to model complex relationships among entities.

Relational Model

• Developed by E. F. Codd in 1970.
• Data represented in tables (rows and columns).
• Based on data normalization.
• Stored in fixed table structures.
• Manipulated using SQL.

Object-Oriented Model

• Data stored as objects.
• Objects contain data and methods.
• Manages complex data types (e.g., images, audio, video).

Entity-Relationship (ER) Model

• Illustrates how entities (e.g., people, objects) relate within a system.
• Uses diagrams for relational database design.
• Employing symbols (rectangles, diamonds, ovals) to depict entities, relationships, and attributes.
• ER models provide a standardized approach to visualizing data relationships.

Keys in DBMS

• Attributes that uniquely identify a tuple (row).
• Establish relationships between different tables.
• Individual values in a key are called key values.

Types of Keys

• Primary Key
• Candidate Key
• Super Key
• Foreign Key
• Composite Key
• Alternate Key
• Unique Key

Primary Key (characteristics)

• Uniquely identifies each record in a table.
• There can only be one primary key in a table.
• Cannot have duplicate values.
• Cannot contain NULL values.

Foreign Key (characteristics)

• Used to establish relationships between tables.
• Values must match the primary key of the referenced table.

Components of ERD (Entity Relationship Diagram)

• Entity: A thing or object
• Relationship: The link between entities
• Attributes: Properties or characteristics of an entity

Attributes

• Attributes describe properties or characteristics of an entity.
• There are various types of attributes, including key attributes, composite attributes, multi-valued attributes, and derived attributes.

Assignment- ER Diagram (Library Management System)

• Students, Subjects, Faculty, Books, Classroom, and Library Staff, are part of the data model
• Attributes for each entity should be identified.
• An ER diagram illustrating the relationships and attributes among these entities should be drawn for the assignment.

Test your knowledge on various database models, including object-oriented databases and hierarchical models. This quiz covers relationships, key features, and typical entities found in different database systems. Perfect for students and professionals looking to reinforce their understanding of database concepts.