The advantages of using a Database Management System over a traditional filing system are
- Data redundancy and inconsistency: Redundancy is the concept of repetition of data i.e. each data may have more than a single copy. The file system cannot control the redundancy of data as each user defines and maintains the needed files for a specific application to run. There may be a possibility that two users are maintaining the data of the same file for different applications. Hence changes made by one user do not reflect in files used by second users, which leads to inconsistency of data. Whereas DBMS controls redundancy by maintaining a single repository of data that is defined once and is accessed by many users. As there is no or less redundancy, data remains consistent.
- Data sharing:The file system does not allow sharing of data or sharing is too complex. Whereas in DBMS, data can be shared easily due to a centralized system.
- Data concurrency: Concurrent access to data means more than one user is accessing the same data at the same time. Anomalies occur when changes made by one user get lost because of changes made by another user. The file system does not provide any procedure to stop anomalies. Whereas DBMS provides a locking system to stop anomalies to occur.
- Data searching: For every search operation performed on the file system, a different application program has to be written. While DBMS provides inbuilt searching operations. The user only has to write a small query to retrieve data from the database.
- Data integrity: There may be cases when some constraints need to be applied to the data before inserting it into the database. The file system does not provide any procedure to check these constraints automatically. Whereas DBMS maintains data integrity by enforcing user-defined constraints on data by itself.
- System crashing: In some cases, systems might have crashed due to various reasons. It is a bane in the case of file systems because once the system crashes, there will be no recovery of the data that’s been lost. A DBMS will have the recovery manager which retrieves the data making it another advantage over file systems.
- Data security: A file system provides a password mechanism to protect the database but how long can the password be protected? No one can guarantee that. This doesn’t happen in the case of DBMS. DBMS has specialized features that help provide shielding to its data.
- Backup: It creates a backup subsystem to restore the data if required.
- Interfaces: It provides different multiple user interfaces like graphical user interface and application program interface.
- Easy Maintenance: It is easily maintainable due to its centralized nature.
A Database model defines the logical design and structure of a database and defines how data will be stored, accessed, and updated in a database management system. While the Relational Model is the most widely used database model, there are other models too:
- Hierarchical Model
- Network Model
- Entity-relationship Model
- Relational Model
1. Hierarchical Model:
This database model organizes data into a tree-like structure, with a single root, to which all the other data is linked. The hierarchy starts from the Root data, and expands like a tree, adding child nodes to the parent nodes.
2. Network Model:
This is an extension of the Hierarchical model. In this model, data is organized more like a graph, and are allowed to have more than one parent node.
3. Entity-relationship Model:
In this database model, relationships are created by dividing objects of interest into entities and their characteristics into attributes.
Different entities are related using relationships.
4. Relational Modal:
In this model, data is organized in two-dimensional tables and the relationship is maintained by storing a common field.