May 18, 2014 by Ozgur Ozden
What is Data Model?
Data model can be described as visual representation of data structure in an organization. This data structure may include entities related to real world, sometimes its attributes and relationships between them. Data models helps us to visualize the real world problems and prepares a solid base for the construction of the data base. Preparing a data model is the most time consuming but the most important part of the database design.
It is time consuming because it takes time to discuss the requirements of the database with the right people in the company and establish the correct relations between them.
It is important because once the real world situation is symmetrically projected into and database requirements understood, proper entities attributes are chosen, it is relatively easy to build the database upon and reduce the possible problems and misunderstandings during the design process. In a sense Opencourseware describes database as the blueprint of the functions needed in the database.
Why do we need it?
Broadly speaking we have three different user definition for a database namely application designer, database designer, and end users. In order to have a fully functional and healthy relationship between the users & developers, data model is the main communication tool between them because of its visual appearance. This will increase the understanding and using the same language between the users & developers. Data model also does not contain technical details and information about the hardware or software, it is simply a visual picture that everyone can understand.
Advantages of using a data model
Data model is the bridge and the common base between the developers (database and application)and the end users. Data model can be understood by the end user and corrected if it is necessary and these corrections can be applied to the database by the designers and developers.
Data model creates a common language. Developers and end users can agree on the details of the project and this significantly reduces the misunderstandings, corrections & revisions. As I have mentioned before data modelling takes time but with solid understanding and less revisions development time can be reduced.
Creates a clear representation of entity integrity and referential integrity. This reduces the data redundancy and clearly shows the relations between the attributes and entities.
Data modelling increases the data quality and reliability.
Every business and department has different expectations from a database. For example HR department mostly uses data related with employees, accounting department needs sales figures and the CEO of the company would like to see a bigger picture. So w.th a properly established data model & database, each department can access to relevant data about their departments.
Disadvantages of using a data model
Besides all these advantages people argue some disadvantages with data modelling. A web site named blurtit.com lists these disadvantages as: “Difficult to change in case of an error, Does not contain details, time consuming”
Even Though we have some disadvantages for data modelling, advantages seem more. A visual picture that everyone understands lessens the communication problems and gather the team around the same topic. Any missing links can be seen, real world projection can be established and development time can be reduced. I think It does not matter how long it takes to establish a solid data model, it should be a must for all projects.
1- Coronel, C., Morris, S. & Rob, P. (2011), Database Systems: Design, Implementation, and Management, 9th Ed, Boston, MA: Course Technology, Cengage Learning.
2- Gregg Ricardi (2000) Principles of Database Systems with Internet and Java Applications ,(Online) Avaiable at: http://www.aw-bc.com/info/riccardi/principles/sample.pdf [Accessed at: 13.9.2013]
3- Data Modeling (?) (Online) Available at: http://www.liberty.edu/media/1414/%5B6330%5DERDDataModeling.pdf [Accessed at: 12.9.2013]
4- Jelena Mamčenko (2004) Lecture Notes on INFORMATION RESOURCES (Online) Available at:
http://gama.vtu.lt/biblioteka/Information_Resources/i_part_of_information_resources.pdf [Accessed at: 12.9.2013]
5- The Advantages And Disadvantages Of A Logical Data Model (online) Available at: http://www.blurtit.com/q2268345.html [Accessed at: 12.9.2013]