by The database model is the internal structure of a database system. This describes the internal functionality of the database. Every database system follow at list one data model. This article describes about the data model or database model.Summary of the article:
- What is Data Model or Database Model?
- Types of Data Model
- Hierarchical Data Model
- Network Data Model
- Relational Data Model
What is Data Model or Database Model?
Database Model is the theoretical structure of a database and in which manner data can stored, organized, and manipulated in a database system. Finally we can say Data model is a process to store and retrieve data. In database data are stored in a table. Each table has row and column. Row means record and column means field.
Types of Data Model
There are so many types of data model or database models are present.But they are mainly three types:
- Hierarchical Data Model
- Network Data Model
- Relational Data Model
Hierarchical Data Model
In this structure data is organized as tree structure. Data is present as a parent-child relationship. Each parent may have many children, but each child has only one parent (also known as 1-to-many relationship).
All attributes of a specific record are listed under an entity type. In a database an entity type is the equivalent of a table. Each individual record is represented as a row, and each attribute as a column. Entity types are related to each other using 1:N mappings, also known as one-to-many relationships. This model is first database model developed by IBM in the 1960s.
Examples of Hierarchical Data Model: IMS by IBM, Windows Registry by Microsoft.
Network Data Model
In this structure data is organized as network structure. Like Hierarchical model data is present as parent-child relationship. But the difference is that each child may have multiple parents. That mean many-to-many relationship.
In 1969, the Conference on Data Systems Languages (CODASYL) established the first specification of this model. Then it was finally implemented in 1971.
Relational Data Model
In this model data is stored in relations (tables) and each relation consists of rows and columns. Each relation must have a head and body. Header is the columns and body is the rows. In 1969 E.F. Codd proposed this model. Present most of the commercial database like MS SQL Server, Oracle, MySQL are using this model.
That’s all about Data Model.
