Data and Knowledge Management
Professor xxx xxxxx
October 24, xxxx
A data model is a basis for developing the blueprint for a database, not the database itself. Its objective is to:
· help the users or stakeholders understand clearly the database system that is being implemented based on the information requirements of an organization,
· enable database practitioners to implement the database system exactly conforming to the information requirements.
Thus it has to address the following key questions about a set of data:
- how data will be structured,
- how the integrity would be maintained,
- how data would be manipulated when needed.
In plain words, a data model helps us view how we want to manage data in the future, how we do it now, or how it was done in the past.
Types of Data Models
There are various types of data models, such as:
- Hierarchical Model
- Network Model
- Relational Model
- Object Oriented Data Model
- Multidimensional data model
Although the two models - Hierarchical and Network - are now considered obsolete, they had been in use for several years. Many legacy applications are based on it. So a basic understanding of them is helpful.
In this model, database is organized as a collection of inverted trees of records (that's why the term ‘hierarchy’). Here the records have parent-child relationship. The top record has zero or more child records. The child record acts as the parent for its descendents. Thus the parent-child relationship continues down the tree.
IBM's IMS is a prime example of a DBMS based on Hierarchical model.
· Fast when queries are simple and sequential search is enough to find records
· Highly reliable as it has been in use for a few decades
· Weak query language
· Requires significant amount of coding
· As... [continues]
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