Relational Databases Overview
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Questions and Answers

What relationship type describes the connection where many employees can enroll in many trainings and vice versa?

  • Many to Many (correct)
  • One to Many
  • One to One
  • Many to One

Which normal form requires that all non-key attributes are fully dependent on the primary key?

  • Second Normal Form (correct)
  • Boyce-Codd Normal Form
  • Third Normal Form
  • First Normal Form

In an ER diagram, how are attributes represented?

  • Circle
  • Oval (correct)
  • Diamond
  • Rectangle

What aspect does normalization primarily aim to achieve in a database?

<p>Eliminate data redundancy (C)</p> Signup and view all the answers

What is represented by a dashed underline in an entity's attributes within an ER diagram?

<p>Foreign Key (D)</p> Signup and view all the answers

What is the first step in the process of creating an ER model?

<p>Identify entities (B)</p> Signup and view all the answers

Which normalization form aims to eliminate transitive dependencies?

<p>Third Normal Form (C)</p> Signup and view all the answers

What type of database design process specifies tables, fields, data types, and relationships?

<p>Scheme Definition (D)</p> Signup and view all the answers

What is the main purpose of foreign keys in a relational database?

<p>To establish a link between different tables. (C)</p> Signup and view all the answers

Which of the following statements accurately describes a primary key?

<p>It uniquely identifies each row in a specific table. (D)</p> Signup and view all the answers

What role do relationships play in maintaining data integrity within a relational database?

<p>They prevent invalid data entries from occurring. (A)</p> Signup and view all the answers

How do entity relationship diagrams contribute to relational database design?

<p>They assist in understanding how entities interact and relate. (B)</p> Signup and view all the answers

Which of the following is a benefit of reduced data redundancy in a relational database?

<p>It allows for simpler data retrieval and handling. (D)</p> Signup and view all the answers

What is the significance of efficient data retrieval in relational databases?

<p>It allows for complex queries that span multiple tables. (D)</p> Signup and view all the answers

In a relational database, how is a table fundamentally structured?

<p>By both rows (records) and columns (fields). (B)</p> Signup and view all the answers

What does the elimination of data redundancy specifically help to achieve in relational databases?

<p>Increased storage efficiency and clarity. (D)</p> Signup and view all the answers

Flashcards

Relational Database

A database system where data is organized into tables with rows and columns, and relationships between tables are established through primary and foreign keys.

Table

A fundamental building block of a relational database, containing rows (records) and columns (fields). Each table represents a specific entity.

Primary Key

Unique identifiers that define each row in a table.

Foreign Key

Columns in a table that reference rows in another table, establishing relationships between entities.

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Data Integrity

The relationships between tables ensure data accuracy and consistency. Foreign keys enforce data integrity by preventing invalid relationships.

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Efficient Data Retrieval

Using relationships between tables allows for complex queries to retrieve related data, e.g., finding all orders placed by a specific customer.

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Reduced Data Redundancy

Relationships between tables help avoid redundancy, by storing related data in separate tables and linking them through keys.

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Entity Relationship Diagram (ERD)

A diagram used to visually represent entities (tables), their attributes, and the relationships between them in a relational database.

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One-to-One Relationship

One entity is associated with only one other entity. Example: One person has one DNI.

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One-to-Many Relationship

One entity can be associated with multiple instances of another entity. Example: One school has many students.

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Many-to-One Relationship

Multiple entities can be associated with one instance of another entity. Example: Many employees work in one store.

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Many-to-Many Relationship

Multiple entities can be associated with multiple instances of another entity. This requires an intermediary table. Example: Many employees enroll in many trainings.

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Normalization

The process of organizing data in a database to reduce redundancy and improve data integrity.

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1st Normal Form (1NF)

A database structure where each column contains only atomic values (single words or numbers).

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2nd Normal Form (2NF)

A database structure where all non-key attributes are fully dependent on the primary key. Eliminates partial dependencies.

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3rd Normal Form (3NF)

A database structure where all non-key attributes depend only on the primary key, not other non-key attributes. Eliminates transitive dependencies.

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Study Notes

Relational Databases

  • Relational databases store related data points in tables
  • Tables consist of rows (records) and columns (fields)
  • Each table represents a specific entity
  • Columns define attributes, rows contain data instances

Relationships

  • Essential for linking tables and ensuring data integrity
  • Established through keys:
    • Primary keys uniquely identify each row in a table
    • Foreign keys link a row in one table to a row in another table

Why Relationships Matter

  • Data integrity: maintains consistency and accuracy of data
  • Prevents invalid data insertion (e.g., linking to a non-existent customer)
  • Efficient data retrieval: allows complex queries across multiple tables
  • Reduced data redundancy: avoids duplication of data

Entity Relationship Diagrams (ER Diagrams)

  • Used for conceptual design in relational databases
  • Assists in identifying entities, attributes, and relationships
  • Show relationships between entities

Relationship Types

  • One-to-one (one entity relates to only one other entity)
  • One-to-many (one entity relates to many others)
  • Many-to-many (many entities relate to many others – requires an intermediate table)

Normalization

  • Organizes data to avoid redundancy and improve efficiency
  • Eliminates data redundancy and ensures data integrity
  • Uses primary and foreign keys
  • Reduces transitive dependencies

Normal Forms

  • First Normal Form (1NF): Each column contains atomic values (single words/numbers)
  • Second Normal Form (2NF): Eliminates partial dependencies (non-key attributes depend on only part of the primary key)
  • Third Normal Form (3NF): Eliminates transitive dependencies (non-key attributes depending on other non-key attributes)

Database Design

  • Process of defining database structure, storage, and retrieval mechanisms
  • Creates a blueprint for data storage and management
  • Includes scheme definition (tables, fields, data types, relationships), normalization (data integrity and redundancy reduction), physical implementation (how the database is stored), and performance optimization (query speed)

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Description

This quiz explores the fundamentals of relational databases, focusing on how data is stored in tables and the importance of relationships. Learn about primary and foreign keys, data integrity, and Entity Relationship Diagrams (ER Diagrams) that aid in conceptual database design.

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