In making a database or a relational database, preferably predetermined attributes and relation is. What's Attributes and Relationships? Here I will explain in more detail. In this time, I will discuss about the Attributes and Relationships on ER Diagram.

Entity Relationship Diagram or ER diagrams is relationship diagram to create a database. Two components of ER Diagrams is attribute and relation.

Here's an explanation of Attributes and Relationships on ER Diagram more clearly:

1. Attribute

In making the ER model, we must note the position of the attributes in the entity. Should we distinguish, where the Primary Key attribute and what is not (descriptive attributes). example:
  • At the Student Entity, as the primary key is nim for the most unique, whereas other attributes (nama_mhs, alamat_mhs, and date of birth) is a descriptive attribute
  • In Car Entities, as the primary key is the license plate number, while other attributes are: brand, type, year of manufacture, etc..

2. Relation

Indicate a relationship between the number of entities derived from the set of different entities. Collection of all relationships between the entities contained in the set of the form SET OF RELATIONSHIPS entitas2. There are several kinds of relationships: one to many, one to one, many to many.

In addition, cardinality / Degrees relation indicates the maximum number of entities that may relate to the entity in another entity set. A good Information System need a good database.

That was a brief description of Attributes and Relationships on ER Diagram. If there are errors or omissions, please justified or added. May be useful.

0 komentar

Related Posts Plugin for WordPress, Blogger...