Lecture 5 Revision

MVC – Creating CRUD Applications

Base Template View

• Create a HTML template that keeps the full page HTML (including the Header and Footer)
• Define sections for content
• Can have multiple sections
• Other views can inherit the template and then just need to include content for the sections

• serves to reduce duplication
• keep similar files together

Base Template

• only done one here, could have any number of them

• this is the actual HTML I am giving for this section
• base template is a skeleton with slots - placeholder for page content
  • create the outline of these components separately

Create Read Update Delete (CRUD)

• Definition of CRUD:
  • CRUD stands for Create, Read, Update, and Delete. These are the four basic functions of persistent storage.
• Foundation of User Interfaces:
  • CRUD operations form the foundation of user interfaces in many applications, enabling users to interact directly with data.
• Ubiquity in Web Applications:
  • Almost every web application has a backend database and uses CRUD operations to interact with the data.
• APIs and CRUD:
  • Many RESTful APIs are designed around CRUD operations, mapping HTTP methods (POST, GET, PUT/PATCH, DELETE) to CRUD functionalities.
• Database Operations:
  • At the database level, CRUD corresponds to SQL commands INSERT, SELECT, UPDATE, and DELETE, respectively.

• Design User interfaces to build things

E.g. Customer app

Need an:

• Add button that displays an Add form
• Edit button in each row
• Delete button in each row
• Display the status of the last operation

Example

Designing a Database

• Each table must represent a single subject
• No data item will be unnecessarily stored in more than one table, i.e., No data redundancy
• All non-key attributes in a table are dependent on the primary key
• Each table is void of insertion, update, deletion anomalies
• Objective of normalisation is to ensure that all tables are in at least 3 rd Normal Form (3NF)

First Normal Form

• To achieve 1NF, we need to ensure that each column contains atomic values and there are no repeating groups.
• In this case, we can split the table into two separate tables: "Students" and "Enrollments".

Second Normal Form

• To achieve 2NF, we need to ensure that all non-key columns depend on the entire primary key.

• In the "Enrollments" table, the primary key is a combination of "StudentID" and "CourseID".

• However, the course details (CourseName, CourseCredits, InstructorName) depend only on the "CourseID".

• To resolve this, we can split the "Enrollments" table further into "Enrollments" and "Courses" tables.

• remove partial dependencies

Third normal form

• To achieve 3NF, we need to ensure that there are no transitive dependencies.

Normalisation Overview