Data, Entities, and Relations on Data Modelling

On Information System need a database. Database or Data Base consists of the data. Data represent reality is an entity (object). Where the entity has a sort of an object or item that has been identified previously by placing numbers or so-called Primary Key. In this time, i will share about Data, Entities, and Relations on Data Modelling.


Suppose we have a User entity. The book consists of a number of books, book titles, and author. All that is called Attribute Entities. An entity can be connected with another entity, the relationship is called a relation.  

There are several types of relationships:

• One to One. An entity of data in A, only used by an entity of data in B.
• One to Many. A data on the entity A, is used by many data on the entity B.
• Many to Many. Many data on the entity A, can be used by many data on the entity B.

An entity has a unique attribute to distinguish these entities with other entities. Attribute is called the Primary Key. Examples of the book has a primary key entity nomer_buku. If the entity that book contained the primary key of the issuer entity, then the primary key of the entity Publishers Foreign Key.


That was a brief description of Data, Entities, and Relations on Data Modelling. If there are errors or omissions please justified or added. May be useful.