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Questions and Answers
What is the primary purpose of establishing relationships in a relational database?
What is the primary purpose of establishing relationships in a relational database?
How do foreign keys contribute to data integrity in a relational database?
How do foreign keys contribute to data integrity in a relational database?
Which component of a table uniquely identifies each row within that table?
Which component of a table uniquely identifies each row within that table?
What is an advantage of using entity relationship diagrams in relational databases?
What is an advantage of using entity relationship diagrams in relational databases?
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What does reduced data redundancy in a database imply?
What does reduced data redundancy in a database imply?
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What is essential for defining relationships and the number of instances associated between entities?
What is essential for defining relationships and the number of instances associated between entities?
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Which of the following best describes the structure of a table in a relational database?
Which of the following best describes the structure of a table in a relational database?
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Why are keys important in relational databases?
Why are keys important in relational databases?
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What does the normalization process primarily achieve in database design?
What does the normalization process primarily achieve in database design?
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Which of the following accurately describes a 'many to many' relationship?
Which of the following accurately describes a 'many to many' relationship?
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In an Entity-Relationship diagram, how is a primary key represented?
In an Entity-Relationship diagram, how is a primary key represented?
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Which step in the ER model creation involves identifying the entities involved?
Which step in the ER model creation involves identifying the entities involved?
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Which normal form specifically addresses the elimination of partial dependencies?
Which normal form specifically addresses the elimination of partial dependencies?
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What is the outcome of the physical implementation step in database design?
What is the outcome of the physical implementation step in database design?
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Which of the following methods is NOT typically included in performance optimization of a database?
Which of the following methods is NOT typically included in performance optimization of a database?
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What does the term 'transitive dependency' refer to in the context of the 3rd Normal Form?
What does the term 'transitive dependency' refer to in the context of the 3rd Normal Form?
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Study Notes
Relational Databases
- Relational databases store and access related data points in tables
- Tables consist of rows (records) and columns (fields)
- Each table represents a specific entity
- Columns define attributes, and rows contain data instances
- Relationships link tables to enable complex queries and ensure data integrity
Relationships
- Established through keys
- Primary keys uniquely identify rows in a table
- Foreign keys uniquely identify rows in another table, linking them
- Data integrity is ensured by preventing invalid data insertion
- Example: preventing an order from referencing a non-existent customer
- Efficient data retrieval allows complex queries across multiple tables
- Example: joining Customer and Orders tables to find which customer placed which order
- Reduced data redundancy by storing related data in separate tables
- Example: storing customer details in one table (Customers) and referencing it in another (Orders)
Entity Relationship Diagrams (ERDs)
- Conceptual in Relational Databases
- Aid in identifying entities, attributes, and relationships between entities
- Define relationships by determining how entities interact
- One-to-one (one person has one DNI)
- One-to-many (one school has many students)
- Many-to-one (many employees work in one store)
- Many-to-many (many employees can enroll in many trainings; many trainings can have many employees enrolled)
- Use intermediate tables when many-to-many
- Guide table creation, defining primary keys, foreign keys, and constraints
- Essential for data integrity
Normalization
- Organizes data efficiently to avoid redundancy and ensure accuracy
- Eliminate data redundancy
- Use primary and foreign keys
- Reduce transitive dependencies
- First Normal Form (1NF): each column contains only atomic values
- Second Normal Form (2NF): eliminate partial dependencies, ensure all non-key attributes fully depend on the primary key
- Third Normal Form (3NF): eliminate non-key attributes that depend on another non-key attribute
Database Design
- Defines database structure, storage, and retrieval mechanisms
- Detailed blueprint of how data is stored, accessed, and managed
- Scheme Definition: specifies tables, fields, data types, and relationships
- Normalization: ensures data integrity by minimizing redundancy
- Physical Implementation: determines how the logical schema is physically stored and accessed
- Performance optimization: enhances performance through indexing, partitioning, and query optimization
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Description
Test your knowledge on relational databases and their core components. This quiz covers topics such as tables, rows, columns, and the relationships between different data points. You'll explore how primary and foreign keys maintain data integrity and enhance query efficiency.
