Overview of Database Management System (DBMS) – Part 2
Database Centric Method for Information Handling
Think through, an instance of a banking organization which saves data for every single customer as well as their respective savings accounts too. Unique method to save the data on a workstation is to stock it in operating system (OS) files. In the direction of letting end users to alter the data, the system has several application programs which alter the files, including the following modules:-
· The software module for debiting or crediting of a savings account.
· The software module for adding a fresh savings account.
· The software module for finding the reaming balance of a savings account.
· The software module for producing monthly statements for a savings account.
The computer programmer writes these application programs to fulfill the requirements of the banking organization. Fresh application programs are integrated to the system as the necessity grows. For an instance, presume that the banking organization chooses to give current accounts too from the time onwards. Accordingly, the banking organization’s computer programmer develops a fresh everlasting file which has every data for all the current accounts that are kept by the banking organization, as well as it might be require to write a fresh application programs to handle the circumstances which did not happened with the savings accounts, but may happen with the current accounts like – overdrafts. Therefore, as period passes by, the system gets additional files as well as new application programs are also added into.
This classic file processing system (FPS) is maintained by means of an orthodox operating system (OS). The system stocks the everlasting data over numerous files, as well as it requires diverse application programs to pull the data from, in addition to add any fresh data to, the correct files. Earlier organizations typically kept data in such systems, now-a-days Database Management Systems (DBMS) is used for this process.
Database Management Systems (DBMS) has been chosen over the file processing system (FPS) because file processing system (FPS) has a number of key disadvantages:
· Information repetition & discrepancy – As the dissimilar computer programmers develops the files as well as application programs over an extensive period of time, the several files are probably to have dissimilar file – formats then the programs might be coded in some different programming languages. Furthermore, the identical data might be repeated in numerous files. For an instance, the email ID plus mobile number of a specific customer might be present in a file which contains the savings account details as well as in a file which contains the current account details. This repetition leads to greater storing as well as right to use cost. Furthermore, it might lead to information discrepancy; which means, the several replicas of the identical information might no longer agree with each other. For an instance, an altered customer mobile number might be updated in the current account details however not in other places of the system.
· Trouble in retrieving information – Think through, an instance that a banking organization’s officer wants to get the names of every single customer who are residing inside a specific PIN code of an area. The officer requests the information handling unit to produce such a report. Now, as the developer of the banking system did not forecasted this type of demands, so as a result there is no such application program in the system to handle the request. However, there is an application program for producing the report of every customer. Now, the banking officer has two options, one to get the report of every customer and then excavate the wanted data by hand and secondly to request a system programmer to write the essential application program. Mutually either of the substitutes is clearly inadequate. Presume that such a program is written, and installed in the system, but after some days later, the same banking officer wants to filter that record and want to get a fresh record of only those customers who have a savings account balance of $ 5,000 or more. As predictable, an application program to produce such a record does not exist, and all over again, the banking officer has the earlier two choices in his or her hand, and neither of which is acceptable. The opinion here is that orthodox file processing system (FPS) backgrounds do not permit desirable information to be recovered in a suitable as well as effective way. Additional quick to respond information recovery systems are vital for overall usage.
· Information isolation – For the reason that information are distributed over several files, plus files might be in dissimilar formats, coding fresh application programs to recover the correct information is problematic.
· Reliability difficulties – The information kept in the database should fulfill some kinds of reliability constrictions. For an instance, the remaining balance of a savings account in a bank should by no means drop lower than an agreed amount like $ 10. System developers apply these constrictions in the system by means of adding correct coding in the several application programs. But, when fresh constrictions are introduced, it is problematic to alteration the programs to impose them. The problematic situation is compounded at the time when constrictions include more than a few information pieces from dissimilar files.
· Atomicity difficulties – A workstation system, same like any other automatic or electrical gadgets, is bound to be failed by nature. In lots of applications, it is vital that, if a failure happens, then the information should be reinstated in reliable form that was earlier to the failure. Think through, an instance that an application program is to transfer $ 10 from savings account A to savings account B. Now, if a system failure happens in the course of the implementation of the application program, it is imaginable that the $ 10 was debited from savings account A on the other hand was not credited to savings account B, causing in an unreliable database state. Obviously, it is vital to have database reliability which is both the credit as well as debit should happen simultaneously; otherwise the total transaction should rollback. The funds transfer should be ATOMIC; it should occur in totality or else not at all. It is problematic to confirm atomicity in an orthodox file processing system (FPS).
· Simultaneous access irregularities – Intended for the complete performance efficiency of the system as well as quicker response back, a lot of systems permit several end users to alter information concurrently. For such type of situations, communication of simultaneous alter might end in erratic information. Think through, an instance of banking savings account A, having $ 100. If two customers withdraw money say $ 25 as well as $ 10 respectively from the savings account A at the identical time from some different locations, the outcome of the simultaneous executions might keep the savings account in an improper or unreliable state. Presume that the application program running for every single withdrawal retrieve the old account balance, decrease the amount that has been withdrawn and writes the effect back to the account balance field. Now, if the two application programs executes simultaneously, they might both read the value as $ 100, as well as write back $ 75 and $ 90 respectively. Subject to which application program writes the value last, the savings account might have an account balance of either $ 75 or $ 90 rather than the precise value of $ 65. To safeguard in contradiction of this risk, the system should keep some sort of observation. However, observation is problematic to be offer for the reason that information might be retrieved by means of many dissimilar application programs which have not been synchronized beforehand.
· Safety difficulties – Not every single end user of the database system must be capable to access the information. For an instance, in a banking system, payroll employees should get access to only that portion of the database which has data for the several bank employees. They must not be able to access the data about customer accounts (savings or current). However, as the application programs are introduced to the system in an ad hoc method, implementing this type of safety constrictions is hard.
These problems, between others, encouraged the improvement of Database Management System (DBMS.
In the upcoming part we will be discussing the different Features of Database and the Advantages & Disadvantages of Database Management System (DBMS).