Traditional and DBMS Environment

 

File-based System

File-based systems were an early attempt to computerize the manual filing system.  File-based system is a collection of application programs that perform services for the end-users.  Each program defines and manages its data.

However, five types of problem are occurred in using the file-based approach:

Separation and isolation of data

When data is isolated in separate files, it is more difficult for us to access data that should be available.  The application programmer is required to synchronize the processing of two or more files to ensure the correct data is extracted.

Duplication of data

When employing the decentralized file-based approach, the uncontrolled duplication of data is occurred.  Uncontrolled duplication of data is undesirable because:

i.      Duplication is wasteful

ii.     Duplication can lead to loss of data integrity

Data dependence

Using file-based system, the physical structure and storage of the data files and records are defined in the application program code.  This characteristic is known as program-data dependence.  Making changes to an existing structure are rather difficult and will lead to a modification of program.  Such maintenance activities are time-consuming and subject to error.

Incompatible file formats

The structures of the file are dependent on the application programming language.  However file structure provided in one programming language such as direct file, indexed-sequential file which is available in COBOL programming, may be different from the structure generated by other programming language such as C.  The direct incompatibility makes them difficult to process jointly.

Fixed queries / proliferation of application programs

File-based systems are very dependent upon the application programmer.  Any required queries or reports have to be written by the application programmer.  Normally, a fixed format query or report can only be entertained and no facility for ad-hoc queries if offered.

File-based systems also give tremendous pressure on data processing staff, with users’ complaints on programs that are inadequate or inefficient in meeting their demands.  Documentation may be limited and maintenance of the system is difficult.  Provision for security, integrity and recovery capability is very limited.

Database Approach

In order to overcome the limitations of the file-based approach, the concept of database and the Database Management System (DMS) was emerged in 60s.

Advantages

A number of advantages of applying database approach in application system are obtained including:

Control of data redundancy

The database approach attempts to eliminate the redundancy by integrating the file.  Although the database approach does not eliminate redundancy entirely, it controls the amount of redundancy inherent in the database.

Data consistency

By eliminating or controlling redundancy, the database approach reduces the risk of inconsistencies occurring.  It ensures all copies of the idea are kept consistent.

More information from the same amount of data

With the integration of the operated data in the database approach, it may be possible to derive additional information for the same data.

Sharing of data

Database belongs to the entire organization and can be shared by all authorized users.

Improved data integrity

Database integrity provides the validity and consistency of stored data.  Integrity is usually expressed in terms of constraints, which are consistency rules that the database is not permitted to violate.

Improved security

Database approach provides a protection of the data from the unauthorized users.  It may take the term of user names and passwords to identify user type and their access right in the operation including retrieval, insertion, updating and deletion.

Enforcement of standards

The integration of the database enforces the necessary standards including data formats, naming conventions, documentation standards, update procedures and access rules.

Economy of scale

Cost savings can be obtained by combining all organization’s operational data into one database with applications to work on one source of data.

Balance of conflicting requirements

By having a structural design in the database, the conflicts between users or departments can be resolved.  Decisions will be based on the base use of resources for the organization as a whole rather that for an individual entity.

Improved data accessibility and responsiveness

By having an integration in the database approach, data accessing can be crossed departmental boundaries.  This feature provides more functionality and better services to the users.

Increased productivity

The database approach provides all the low-level file-handling routines.  The provision of these functions allows the programmer to concentrate more on the specific functionality required by the users.  The fourth-generation environment provided by the database can simplify the database application development.

Improved maintenance

Database approach provides a data independence.  As a change of data structure in the database will be affect the application program, it simplifies database application maintenance.

 

 

 

 

 

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