Podcast
Questions and Answers
Cal é o primeiro paso na normalización de datos?
Cal é o primeiro paso na normalización de datos?
A que se refire a 1FN na normalización?
A que se refire a 1FN na normalización?
Que característica é esencial na 2FN?
Que característica é esencial na 2FN?
Que implica a normalización de 3FN?
Que implica a normalización de 3FN?
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Que se debe evitar durante o proceso de normalización?
Que se debe evitar durante o proceso de normalización?
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Cal é o obxectivo principal da normalización?
Cal é o obxectivo principal da normalización?
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En que situación sería inapropiada a normalización?
En que situación sería inapropiada a normalización?
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Cal é un resultado positivo da normalización?
Cal é un resultado positivo da normalización?
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Study Notes
Video Tutorial 5: Databases
- The tutorial is for CFGS Web Application Development and Multiplatform Application Development students
- The tutorial covers database normalization
- The tutorial includes a complete exercise
Normalization
- The lesson will include a full E-R model
- A Relational Model practice exercise
- Key Concepts of Normalization
- A General Summary of the concepts
Exercise 1
- Students need to create an Entity Relationship diagram and convert it to a relational model.
- The model should meet the first normal form.
- The exercise details involve handling multiple PACs (assignments) for a student and calculating the maximum possible grade.
- Students need to determine the attributes for a student (ID, name, age, and languages).
- Student assignments include the ID, and number of questions, and the date of opening, closing, days accessible, and the maximum points for the assignment. Each question has a value of 0.2 points.
Exercise 1 Diagram
- A diagram illustrating the relationship between 'Alumno' (Student) and 'PAC' (Assignment) data points.
- The diagram shows a many-to-many relationship between the two entities.
- The 'hacer' entity represents the concept of students completing assignments.
- Attributes like 'Id alu' (student ID), 'edad' (age), 'Nombre' (name), 'nota' (grade), 'tiempo' (time).
- Other attributes for PAC data like 'Id pac', 'fecha_aper', 'dias_apertura', 'fecha_cierre', n'numero_preg', 'puntuación_max'
Exercise 1 Summary
- The solution, which includes an E-R and a Normalized model for the database example presented.
- The diagram illustrates attributes and relationships between different tables (e.g. 'ALUMNO','idiomas', 'HACER', 'PACS').
Exercise 2
- Normalizing the "Alquiler" (Rentals) table to 3rd normal form (3NF).
- Students must consider restrictions on the table like multiple rentals of the same book but on different dates.
- The table needs a primary key composed of columns such as 'FechaDeAlquiler', 'CódigoLibroAlquilado', 'CódigoUsuario'.
- Addressing issues like updating user phone numbers, and updating editorial locations.
- Students need to review the restrictions and other important considerations relating to rentals.
Exercise Solution (Normalisation)
- The exercises show how to go from one table to 11.
- Detailed information for "Alquileres" (rental) tables to include attributes such as "FechaDeAlquiler", "CódigoLibroAlquilado","CódigoUsuario","Título Libro", "CódigoEditorial" and "NombreEditorial".
- The process to convert from one table to six related tables in order to normalize the data to 3NF.
Normalization to 1NF
- Eliminating multi-valued fields (e.g., multiple authors, phone numbers) is part of reaching first normal form.
- Creating separate tables for phone numbers and authors are examples here
Normalisation to 2NF
- Ensuring that attributes depend on the entire primary key, not just a portion, is the core of 2NF.
- Removing attributes that are only predicated on partial components of primary keys.
Normalization to 3NF
- Eliminating transitive dependencies.
- Breaking down attributes relying on other non-key attributes.
- Creating a new table, "EDITORIALES", to store editorial information, separate from the "LIBROS" table.
Exercise Summary (Overall)
- The overall solution provided involves normalizing a database to the 3NF.
- Separate tables for rentals, users, books, authors, and editorial information are created.
- Relationships between these tables are shown using foreign keys.
Questions for Review
- The normalization exercise itself.
- Converting E-R diagrams to models.
- The number of strong entities involved.
- The different relationships and their number.
- Why "FechaAlquiler" is a key field in the "Alquileres" table.
- Whether "Autores" is an entity or an attribute.
Contextualization
- Conceptual, Logical, and physical stages of database development.
- Explaining which diagram helps visualize database structure.
- How to use a diagram to display database structure for ease of development.
- Explaining how a model is converted into a usable database.
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Description
Este cuestionario está dirixido a alumnos de CFGS en Desenvolvemento de Aplicacións Web e Aplicacións Multiplataforma. A lección céntrase na normalización de bases de datos, incluíndo un modelo E-R completo e exercicios prácticos relacionados. Os estudantes deberán crear un diagrama de relación de entidades e conversalo a un modelo relacional que cumpran coa primeira forma normal.
