File organization concept

DATABASE AND INFORMATION SYSTEM

File organization concept

A computer system organizes data in a hierarchy that starts with bit and progress to byte, field, record, file and database.

• A group of bit is called byte that represents character.
• A field is a data element that consists of grouping of characters that describes a particular attribute of an entity. In other words, a field is a location in which particular types of data is stored.

For example: employee-record might contain field to store last-name, first-name, and address and so on. Individual fields are characterized by their maximum length and type of data that can be placed on them.

• Related fields of data can be grouped to form a record. Thus, a record represents a collection of attributes that described an entity.
• A database composed of records, each of which contains field together with a set of operations for searching, sorting, and other functions. In other words, it is an integrated collection of logically related data elements.

Problems with traditional file environment

In traditional file processing, files are maintained by different departments. The common problems which may occur with traditional file environment are listed below:

1. Data Redundancy (Duplication): Data redundancy means presence of duplicate data in multiple files. In traditional file processing, file creates space complexity because same data are repeated in multiple files.
2. Data consistency problem: When we update the data of one file, other files are not updated itself which creates problem of consistency.
3. Limited query facility: Query facility means the set of instruction to indicate a file. And the file system has the limited instruction to find the required files.
4. Limited security level: Security level is only up to file level. It doesn’t provide security for record, field and data level
5. Program data dependence: Different program are used to create file and data. Thus, data are dependent on program.
6. Lack of flexibility
7. Poor security
8. Lack of data sharing and availability

Database approach to data management

Database: Database is a collection of data, organized to serve many applications efficiently by centralizing data and controlling redundant data. Database technology solves many problems of traditional file organization. A single database services multiple application in a database approach, rather than storing data in a separate file for each application, data are stored in as to appear to user as being stored in only one location.

DBMS: It is software that is used to centralized data, managing data efficiently and providing access to the stored data by application program. It acts as an interface between application program and physical data files. DBMS separates logical and physical views of data which makes programmer and end users easy to know where and how the data are actually stored. The logical view presents data as they would be perceived by end-user whereas physical view shows how data are actually organized and structured on a physical storage media.

DBMS solves the problem of traditional file environment i.e. control redundancy, eliminates inconsistency, uncouples programs and data, enables organizations to centrally manage data, and security.

Advantages of database approach to data management

• DBMS reduces data redundancy and inconsistency by minimizing isolated files in which same data are repeated.
• DBMS uncouples program and data, enabling data to stand on their own. So, the problem of program-data dependence is solved.
• In a DBMS, security can be applied to database level, file level, record level and even a field level. Hence, the security is enhanced in a database processing. In a database approach, data are centrally managed.

Capabilities of DBMS

A DBMS include capabilities and tools for organizing, managing and accessing the data in the database. The most important capabilities of DBMS are listed below:

1. Data definition: DBMS have a data definition capability to specify structure of the context of the database. It is used to create database table and define characteristics of the field in each table.
2. Data dictionary: A data dictionary is an automated and manual file that stores definition of data element and their characteristics.
3. Data manipulation: Most DBMS has a specialized language called a Data manipulation language that is used to add, change, and retrieve data in the database. The most used data manipulation language is structured query language. DML is mainly used for query and reporting.

Database design

• No redundancy, relationship between business process, accessible as per logical and physical view.
• To create a database, we must understand the relationship among the data, type of data, how the data will be used and how the organization will need to change and manage data from a organization perspective.
• The database requires both conceptual as well as physical design.
• A good database designer will follow these steps:

1. Needs analysis
2. User analysis
3. Data analysis
4. Determine field
5. Initial table design

• Design process should identify the relationship among data element and the most efficient way of grouping data element together to meet business information requirement.
• The database design process should also identify redundant data element and grouping of data element required for specific application program.
• While designing database, the complex grouping of data must be streamlined to minimize redundant data element and many-to-many relationship.
• While designing a database, a database-designer should always try to enforce referential integrity; rules to ensure the relationship between tables remains consistent.
• Database designer should document their data model with entity-relationship diagram which illustratesa the relationship between different entities and how each entity has a relation to other entity.

The data model should be right because the system would not be able to serve the business well if there is a problem in a data model.

DBMS Vs File System

Reference

Laudon, Laudon, "Management Information Systems Managing the Digital Firm", twelfth edition