CSC 1143 FUNDAMENTAL OF DATABASE ::Week 2:: DATABASE Vs FILE BASED APPROACH
WAN RAMLAH WAN RAHIMI (WAN) 2 File Based Approach (Traditional) File System Approach (Computerized) Database Management System (DBMS) (Computerized) “File” Based Approach vs File System Approach vs DBMS
❑Filing System/Manual System ❑Files stored in a cabinet ❑For safety, they are labeled and stored in one or more places ❑For security, they may have locks or located in secure areas of building ❑When we need to look for something, we search through the filing system from the first entry until we find what we want ❑While organizations grew, files became more complex and keeping track of data became more difficult WAN RAMLAH WAN RAHIMI (WAN) 3 File Based Approach (Traditional)
❑Is a collection of application programs that perform services for the end users such as the production of reports. Each program defines and manages its own data. ❑Use extensive programming in a third-generation programming language (3GL) such as COBOL,FORTRAN and BASIC. WAN RAMLAH WAN RAHIMI (WAN) 4 File System Approach
WAN RAMLAH WAN RAHIMI (WAN) 5 A File System Employees Personal Department Accounting Department Sales Department Inventories Customers Sales Accounts
1. Separation and isolation of data into files • Data has to be separate or manage into files by department or as request by manager • It is more difficult to access the data in multiple files • Each program maintains its own set of data. • Users of one program may be unaware of potentially useful data held by other programs. WAN RAMLAH WAN RAHIMI (WAN) 6 Limitations of File System Approach (Problems)
2. Duplication of data • Due to the decentralized approach taken by each department, some data duplicate with multiple files • It costs time and money to enter the data more than once • Duplication can lead to loss of data integrity; the data is no longer consistent • When there are changes, data needs to be update with all files related. If there are lack of entering data, it will course a more serious problems especially when it relates with payroll. 3. Data dependence • The physical structure of data files are defined in the application code • Any changes to data format needs modification to the related programs WAN RAMLAH WAN RAHIMI (WAN) 7 Limitations of File System Approach (Problems)
4. Incompatible file formats 1. Data structure is dependent on the application program. 2. Therefore, its difficult to joint the process between difference file format. 5. Fixed queries of application programs 1. File-Base Systems are very dependent upon the application programmer. 2. Any queries or reports that are required have to be written by the application programmer. 3. Access to the files was restricted to one user at a time. 4. Any new requirement needs a new program. WAN RAMLAH WAN RAHIMI (WAN) 8 Limitations of File System Approach (Problems)
❑ Control of data redundancy The database approach attempts to eliminate the redundancy by integrating the file. ❑ Data consistency By eliminating or controlling redundancy, the database approach reduces the risk of inconsistencies occurring. ❑ Sharing of data Database belongs to the entire organization and can be shared by all authorized users. WAN RAMLAH WAN RAHIMI (WAN) 9 Advantages of Database Approach
❑ Improved data integrity Database integrity provides the validity and consistency of stored data. ❑ Improved security Database approach provides a protection of the data from the unauthorized users. ❑ Enforcement of standards The integration of the database enforces the necessary standards including data formats, naming conventions, documentation standards, update procedures and access rules. WAN RAMLAH WAN RAHIMI (WAN) 10 Advantages of Database Approach
❑ Complexity Database management system is an extremely complex piece of software. Therefore, training for the administrators, designers and users is required. ❑ Size The database management system consumes a substantial amount of main memory as well as a large number amount of disk space in order to make it run efficiently. WAN RAMLAH WAN RAHIMI (WAN) 11 Disadvantages of Database Approach
❑ Cost of DBMS 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. ❑ Higher impact of a failure 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. WAN RAMLAH WAN RAHIMI (WAN) 12 Disadvantages of Database Approach
❑ Performance As the database approach is to cater for many applications rather than exclusively for a particular one, some applications may not run as fast as before. ❑ Cost of conversion 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. WAN RAMLAH WAN RAHIMI (WAN) 13 Disadvantages of Database Approach
Comparison between file-based system and database system in term of data integrity File-based system Database system In file-based system, data is stored more than once in different files, that means duplicate data may occur in these files. In some cases, various copies of the same data may contain different values. Example: To update a value of StudentID, the same data must be updated in all files, otherwise different file may have different StudentID for the same student. Because of this problem, it is possible that data may not be in consistent state. Therefore, when a system contains this type of error, it loses integrity. Database keep all of the information in one place. Data integrity is enforced in database system since it provides procedures to define and assure the integrity of the data stored within the database. These procedures will automatically update the data once user execute insert, update, or delete operations to the records. For example, if value of employeeID in Staff table is updated, the same employeeID in another table will also automatically be updated.