Data Model in DBMS
A model is an abstraction process that represent essential features without including the background details or explanations. It hides superfluous details while highlighting details pertinent to the application at hand.
A data model is a mechanism that provides this abstraction for database applications. Data modelling is used for representing entities of interest and their relationships in the data base.
A data model defines the logical structure of a data base means that how data is connected to each other and how they are processed and stored inside a system.
A number of models for representing data have been developed. As with programming languages, there is no best choice for all applications but the models maintains the integrity of the by enforcing a set of constraints.
Data models differ in their method of representing the associations amongst entities and attributes. The main models or approach are:
- The Hierarchical Model – Tree Structure
- The Network Model – Plex Structure
- The Relational Model – Normalised Structure
- The ER Model -Conceptual Model
Click on these models to know more .
Data Model Structure and Constraints –
- To define the database structure, Constructs are used
- Constructs typically include elements (and their data types) as well as group of elements (Example- Entity, Record, Table), and relationships among such groups.
- Constraints specify some restriction on valid data; These constraints must be enforced at all times.
Data Model Operations –
These operations are used for specifying database retrievals and updates by referring to constructs of the data model. The Operations may include basic model operations as well as user defined operations.
Basic Model Operations :
User Defined Operations Example :
- update_inventory etc.
The hierarchical model is the oldest DBMS model and the object oriented DBMS being the newest data model.
|Identifying and Non Identifying Relationships||Hierarchical Model|
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