SkillRary

 Data Model gives us an idea that how the final system will look like after its complete implementation. It defines the data elements and the relationships between the data elements. Data Models are used to show how data is stored, connected, accessed and updated in the database management system. Here, we use a set of symbols and text to represent the information so that members of the organization can communicate and understand it. Though there are many data models being used nowadays but the Relational model is the most widely used model.

A database model shows the logical structure of a database, including the relationships and constraints that determine how data can be stored and accessed. Individual database models are designed based on the rules and concepts of whichever broader data model the designers adopt. Most data models can be represented by an accompanying database diagram.

The primary goal of using data model are:

• Ensures that all data objects required by the database are accurately represented. Omission of data will lead to the creation of faulty reports and produce incorrect results. 
• A data model helps design the database at the conceptual, physical and logical levels.
• Data Model structure helps to define the relational tables, primary and foreign keys and stored procedures.
• It provides a clear picture of the base data and can be used by database developers to create a physical database.
• It is also helpful to identify missing and redundant data.
• Though the initial creation of data model is labour and time consuming, in the long run, it makes your IT infrastructure upgrade and maintenance cheaper and faster.

The following are the types of Data Models:

Hierarchical Model

The hierarchical Model was the first DBMS model. This model organizes the data in the hierarchical tree structure. The hierarchy starts from the root which has root data and then it expands in the form of a tree adding child node to the parent node. This model easily represents some of the real-world relationships like food recipes, sitemap of a website etc.

Network Model

This model is an extension of the hierarchical model. It was the most popular model before the relational model. This model is the same as the hierarchical model, the only difference is that a record can have more than one parent. It replaces the hierarchical tree with a graph.

Entity-Relationship Model

Entity-Relationship Model or simply ER Model is a high-level data model diagram. In this model, we represent the real-world problem in the pictorial form to make it easy for the stakeholders to understand. It is also very easy for the developers to understand the system by just looking at the ER diagram. We use the ER diagram as a visual tool to represent an ER Model. ER diagram has the following three components:

• Entities: Entity is a real-world thing. It can be a person, place, or even a concept. Example: Teachers, Students, Course, Building, Department, etc are some of the entities of a School Management System.
• Attributes: An entity contains a real-world property called attribute. This is the characteristics of that attribute. Example: The entity teacher has the property like teacher id, salary, age, etc.
• Relationship: Relationship tells how two attributes are related. Example: Teacher works for a department.

Relational Model

Relational Model is the most widely used model. In this model, the data is maintained in the form of a two-dimensional table. All the information is stored in the form of rows and columns. The basic structure of a relational model is tables. So, the tables are also called relations in the relational model.

Object-Oriented Data Model

The real-world problems are more closely represented through the object-oriented data model. In this model, both the data and relationship are present in a single structure known as an object. We can store audio, video, images, etc. in the database which was not possible in the relational model (although you can store audio and video in relational database, it is advised not to store in the relational database). In this model, two are more objects are connected through links.

Object-Relational Model

As the name suggests it is a combination of both the relational model and the object-oriented model. This model was built to fill the gap between object-oriented model and the relational model. We can have many advanced features like we can make complex data types according to our requirements using the existing data types. The problem with this model is that this can get complex and difficult to handle. So, a proper understanding of this model is required.

Flat Data Model

It is a simple model in which the database is represented as a table consisting of rows and columns. To access any data, the computer has to read the entire table. This makes the modes slow and inefficient.

Semi-Structured Model

Semi-structured model is an evolved form of the relational model. We cannot differentiate between data and schema in this model. Example: Web-Based data sources which we can't differentiate between the schema and data of the website. In this model, some entities may have missing attributes while others may have an extra attribute. This model gives flexibility in storing the data. It also gives flexibility to the attributes. Example: If we are storing any value in any attribute then that value can be either an atomic value or a collection of values.

Associative Data Model

Associative Data Model is a model in which the data is divided into two parts. Everything which has independent existence is called an entity and the relationship among these entities are called association. The data divided into two parts are called items and links.

• Item: Items contain the name and the identifier (some numeric value).
• Links: Links contain the identifier, source, verb and subject.

Context Data Model

Context Data Model is a collection of several models. This consists of models like network models, relational models etc. Using this model we can do various types of tasks that are not possible using any model alone.