The overall assignment deals with characteristics of database system, its approach and how it replaced the file based approach.
In every organization there is need of database. Database is collection of data in a structured and more systematic way that helps in retrieving the data easily and efficiently. Before database system came in to picture there was file based approach in which there were application programs which were used to perform services for end user and produce reports. However every program used to manage its own data. Due to this and various other limitations file system was replaced by database system.
The modern database approach has much advantage that helps not only the organization but also the common people in their day today life.
In the below assignment all the characteristics of database has been described.
Self-describing nature of a database system: A DBMS catalog stores the description of the database. The description is called meta-data which is data about data. This allows the DBMS software to work with different databases.
Insulation between programs and data: Also known as program-data independence. Without making any change to DBMS access programs the data storage structures and operations can be changed.
Data Abstraction: The availability of data model approach helps in hiding the physical view of data i.e. the storage details and other internal level information and provides the conceptual view of database.
Support of multiple views of the data: The database approach allows each user to have their own view of the database which describes only the data of interest to that user. There are various benefits of having multiple views such as:
Sharing of data and multi-user transaction processing: The database approach allows a set of concurrent users to retrieve and to update the database. Spreadsheets cannot offer several users the ability to view and work on the different data in the same file, because once the first user opens the file it is locked to other users. Other users can read the file, but may not edit data. For example, when one user is changing data then the database should not allow other users who query the same data to view the changed, unsaved data. Instead the user should only view the original data.
Controlled access to database may include:
File-based systems were the manual based approached used for managing the files. It’s mainly the collection of application programs that used to provide services for the end-users. Each program was defined for a specific task and can’t be used simultaneously with each other.
However, there are many pitfalls of file based system.
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.
With the use of the decentralized file-based approach, the uncontrolled duplication of data used to occur which can lead to loss of data integrity as well as is wasteful as it occupies unnecessary space in memory storage area.
Using file-based system, the physical structure and storage of the data files and records are defined in the application program code. This makes the file to be program-data dependent. If the user want to make any change in the existing structure it was a difficult a task and will lead to a modification of program. Such maintenance activities are time-consuming and subject to error.
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.
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.
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 of DBMSs
Difference between file system and DBMS [2]
Disadvantages of database approach
The Database approach too has some disadvantages. They are:
Database management system is an extremely complex piece of software. The users must be familiar with its functionality in-order to make full use of it. Therefore, training for the administrators, designers and users is required.
The database management system consumes a substantial amount of main memory as well as a large amount of disk space in order to make it run efficiently.
A multi-user database management system may be very expensive. Even after the installation, there is a high recurrent annual maintenance cost on the software.
When moving from a file-base system to a database system, the company is required to have additional expenses on hardware acquisition and training cost.
As the database approach is to manage many applications rather than exclusively for a particular one, some applications may not run as fast as before.
The database approach increases the vulnerability of the system due to the centralization. As all users and applications reply on the database availability, the failure of any component can bring operations to a halt and affect the services to the customer seriously.
Application of database in an organization
Advantages [4]
There are various advantages of introducing database system approach in an application system. Some of them are discussed below:
In the database approach there is central repository of data that not only helps in avoiding the wastage of storage space but also helps in controlling the redundancy by data integration. It helps in avoiding the duplication of data by following techniques like normalization and key concepts. Thus the data is stored in database table at only one place from where it can be retrieved when needed, by avoiding redundancy.
This is maintained by following the concept “control of redundancy”. If the data is stored at one place in a database then while updating any information the changes will be done at only one place which is reflected at all place where ever it is present in whole database. There is no need to change at all places where that data is present. For example if an employee has a change in his address then only in employee table the address will be changed. From there it will be updated every where in database. Thus it ensures all copies of the data are kept consistent. This helps in maintaining consistency of information throughout the system without any loss or misleading of information.
With the integration of the operated data in the database approach, it may be possible to derive additional information for the same data. All data is stored in a single database, instead of being stored in various other separate files, making the process of obtaining information quicker and in an easy way. For example, in the file-based system of a property company, the Contracts Department does not know who owns a leased property. Similarly, the Sales Department has no knowledge of lease details. Now when we combine these files, the Contracts Department has access to owner details and the Sales Department has access to lease details. Thus more information can be derived now from same available data.
There is central repository of data in a database system that makes it available to the entire organization and can be shared by all authorized users.
Data integrity mainly refers to ensuring that data is recorded exactly as intended and when retrieved it’s in the same way as it was when it was recorded. There should not be any data loss when data is retrieved. It mainly provides the validity and consistency of stored data. The database application has various Integrity Constraints, which are consistency rules that the database is not permitted to violate. One of the constraints is specifying data type for every data item. Another is referential integrity constraint in which a record in one file must be related to records in other files. These constraints help in maintaining integrity of data.
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. Providing the facility of accessible rights in database system for various levels in an organization makes it secure for use. For example, the DBA has access to all the data in the database where as a branch manager may have access to all data that is related to only his branch office. In a similar way a sales assistant may have access to all data relating to properties but don’t have any access to sensitive data such as staff salary details.
The integration of the database enforces the necessary standards including data formats, naming conventions, documentation standards, update procedures and access rules. It helps in maintaining standards among the user in an organization. The sharing of data within departments, exchange of information among the users on various projects become easy following the standard database on a centralized environment.
Using centralized database helps in combining all organization’s operational data into one database with applications to work on one source of data. This helps in cost saving as well as reducing redundancy among the applications. The organizations can invest their money on buying new tools like good processors, storage space and communications devices. Instead of each department buying individually, the organization as whole can do this by saving operational and management time and money.
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.
By having integration in the database approach, data accessing can be crossed departmental boundaries. This feature provides more functionality and better services to the users.
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.
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.
Database can manage concurrent data access effectively. It ensures no interference between users that would not result any loss of information nor loss of integrity.
DBMS provides a variety of user interface like query language for casual users, programming language interface for application programmers, command codes for parametric users, menu-driven interface for standalone users. It provides web based GUI interface to database.
Modern database management system provides facilities to minimize the amount of processing that can be lost following a failure by using the transaction approach.
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