Relational database model
The Internet era moved the information flow on a whole another level. People are overwhelmed with information and they seek for new ways, e-places to store them. Data is everywhere and businesses face many problems when storing that data. That’s why they need a database to collect, organize and search information. Here’s how the relational database model differs from all the other ones.
If you’re reading this, then you probably already know that storing data in a simple file isn’t practical for complex information. Even though data by definition is consisted of physical files, models can be designed to make that information relate, somehow.
At a simple file system model, no modeling techniques are applied. But with larger databases, a model is a “must”. It helps avoid repetition of information repetition and also redundancy.
Except the file system model, there is also a hierarchical model, which structures data as a tree, or an object database model, which structures data as a three-dimensional figure, (but these models aren’t our subject right now).
The model we are talking about today is the Relationship Database Model. This model stores data with relations, or as the user perceives them – in tables. What makes this model so special is that it contains a unique value which connects the components and their attributes, that way creating the physical model of the relationship.
Relational database systems have two main categories: file-based and server-based.
Relational database types:
Here are some relational databases you’re maybe familiar with:
In such order, they are listed by complexity (the first one being the simplest) and each one of them applies to different purposes, from individual usage – to integration in complex business systems. When properly modeled, databases can be the center of decision making in business environments.
There are two types of data projects:
- Data Mining
This type of project involves a client who has data that needs to be looked after.
2. Task Automation
This type of project involves a client with a job that needs to be automated.
The basic building blocks of the relational database model are entities, attributes and relationships.
1. Entities are something, a person, an object, about which the data is to be collected.
2. Attributes are the characteristics of the entity.
There are three kinds of attributes:
- Simple – cannot be subdivided.
- Composite – a group attribute, formed by combining related attributes.
- Multi–valued – takes on more than one value for a given instance of an entity.
3. Relationships are an association among (two or more) entities.
There are also, three types of relationships between entities:
- One-to-one – there is just one association.
- One-to-many – association are not limited to single entities.
- Many-to-many – many entities are related to many associations.
The relationships between different entities are identified with a primary key, which is a unique identifier.
Why did we describe all these elements?
Because as a beginner, you should know that these elements are the basics of the ER diagram. When creating an ER diagram, you should normalize the elements into different tables and use languages in order to read those tables.