Chapter 2

 Chapter 2: Entity Relationship Model 

(Part 2)

Simple Entity Relationship Model (ERD)

     Last Thursday, we started our class as usual at 2pm. We learned about Entity Relationship Model(ERD) that describes interrelated things of interest in a specific domain of knowledge. An Entity Relationship (ER) is a high-level data model that is useful in developing a conceptual design for a database. A basic ER model is composed of entity types (which classify the things of interest) and specifies relationship that can exist between entities (instances of those entity types). An Entity Relationship Diagram (ER) is a graphical representation of an ER model. Represent different types of data and how they relate to each other.

        Here  are the geometric shapes and their meaning in an E-R Diagram. We will discuss these terms in  detail in the next section (Components of a ER Diagram) of this guide so don't worry too much about these terms now, just go through them once.

1. Rectangle: Represents Entity sets.

2. Ellipses: Attributes.

3. Diamonds: Relationship Set

4. Lines: They link attributed to Entity Sets and Entity Sets to Relationship Set.

5. Double Ellipses: Multivalued Attributes.

6. Dashed Ellipses: Derived Attributes.

7. Double Rectangles: Weak Entity Sets.

8. Double Lines: Total participation of an entity in a relationship set. 

Components of ERD

        

This is an example of an ERD answer from a complicated question.

        Next, we are moved to the most exciting part in the class. We played Kahoot for almost 20 minutes and the winner goes to Roy as runner up and followed by Ain and Calvin. They got special prize given by Madam Shamsiah. We were also given some activities in CIDOS. The activities are about knowledge we knew about in Chapter 2 which is Entity Relational Model(ERM) and Entity Relationship Model(ERD). The students was submitted the task directly in CIDOS without need to write on the paper anymore. The task about the difference between ERM and ERD, the entities, the attributes, the diagram and the database using SQL Software.

The difference between ERM and ERD

        Consequently, we did a newly-fresh educational platform in CIDOS called Quizlet that lets us study the topics with interesting and fun quizzes and games. As last week, we also played Kahoot for subtopics that we learnt that day. And as promise, Madam Shamsiah brought the special gifts for this week's winners. The day ended with fun, educational and laughter!