SQL Server Mentalist

Hi friends ,

Continuing from my last post on same series

• BISQL # 69–Laymen to SQL Developer # 1 – Introduction to brand New SQL Server Zero to Basics Series
• BISQL # 70 – Laymen to SQL Developer # 2 – Assignment #1 – Part #1–Introduction to Data and database Why Database exist ?

In this article we are going to cover following points

Why DBMS exist

What is the reason behind DBMS as separate platform

What are limitation of File processing System

All required details for Drawbacks of File Processing System and need

                   My dear friends some of this topic in this series you may seem to boring and one may think what is use of studying this ,But believe me at series end those who really don’t know about SQL server will really have good and ample knowledge to work with SQL server.As some one has said

“An exceptionally knowledgeable person with his deep knowledge of wide ranging subjects has the capability to provide solutions to almost every problem. He has the intelligence required to understand the basic nature of the problem and then work accordingly towards finding it’s solution. He always gives right advice to the right people at the right time.”

So always be core knowledge gainer !!

Now lets get back to our series again…………

In very first era of computer evolution everyone in this world is just using file processing system there is DBMS as such ..

Just imagine all your data from current system transfer into file !! Do you really think is it going to any useful or worth or how every process in this world will going to work .

I know .. Nothing but everything will go crazy !!

What is File Processing System

File processing is the process of creating, storing and accessing content of files. File processing can be used in opening saved files for read only purpose. It can be used to save a new file or displace the existing one. Through file processing we can make new files and save the existing files.

For example we can think any text as file processing system

From Wiki :

A file system (or filesystem) is a means to organize data expected to be retained after a program terminates by providing procedures to store, retrieve and update data, as well as manage the available space on the device(s) which contain it. A file system organizes data in an efficient manner and is tuned to the specific characteristics of the device. There is usually a tight coupling between the operating system and the file system. Some filesystems provide mechanisms to control access to the data and metadata. Ensuring reliability is a major responsibility of a filesystem. Some filesystems provide a means for multiple programs to update data in the same file at nearly the same time.

What are limitation of File Processing System Or Advantages of DBMS

Following are main key points to understand what are limitation of file processing system

• Data Redundancy
• Data Isolation
• Accessing Data
• Data Inconsistency
• Integrity
• Atomicity
• Concurrent Access
• Security
• Time consuming .

Now lets Discuss all points one by one

Data Redundancy

Data redundancy is a data organization issue that allows the unnecessary duplication of data within your file.

Redundant data wastes valuable space.

Applications are developed independently in file processing systems leading to unplanned duplicate files. Duplication is wasteful as it requires additional storage space and changes in one file must be made manually in all files. This also results in loss of data integrity. It is also possible that the same data item may have different names in different files, or the same name may be used for different data items in different files.

Also Data Redundancy means same information is duplicated in several files. This makes data redundancy.

For example : Sonal has given this example w.r.t to access file  as follows

Data redundancy is a data organization issue that allows the unnecessary duplication of data within your file Microsoft Access database. A change or modification, to redundant data, requires that you make changes to multiple fields of a database. While this is the expected behavior for flat file database designs and spreadsheets, it defeats the purpose of relational database designs. The data relationships, inherent in a relational database, should allow you to maintain a single data field, at one location, and make the database’s relational model responsible to port any changes, to that data field, across the database. Redundant data wastes valuable space and creates troubling database maintenance problems.

Data Isolation

This referrers to how one data is isolated from other to make consistency in our Data

Data are scattered in various files, and the files may be in different format, writing new application program to retrieve data is difficult

Accessing Data

File systems are used on data storage devices such as hard disk drives, floppy disks, optical discs, or flash memory storage devices to maintain the physical location of the computer files. They may provide access to data on a file server by acting as clients for a network protocol (e.g. NFS, SMB, or 9P clients), or they may be virtual and exist only as an access method for virtual data (e.g. procfs). This is distinguished from a directory service and registry.

So its very difficult to access data in file processing as Concurrent User are not allow ,More Wait state and difficulties in maintenance

It is not easy to retrieve information using a conventional file processing system. Convenient and efficient information retrieval is almost impossible using conventional file processing system.

Data Inconsistency

Data consistency summarizes the validity, accuracy, usability and integrity of related data between applications and across an IT enterprise. This ensures that each user observes a consistent view of the data, including visible changes made by the user’s own transactions and transactions of other users or processes. Data Consistency problems may arise at any time but are frequently introduced during or following recovery situations when backup copies of the data are used in place of the original data.

Data inconsistency is likely to occur when there is data redundancy. Data
redundancy occurs when the data file/database file contains redundant –
unnecessarily duplicated – data. That’s why one major goal of good
database design is to eliminate data redundancy.

Data Inconsistency means different copies of the same data are not matching. That means different versions of same basic data are existing. This  occurs as the result of  update operations that are not updating the same data stored at different places.

Example: Address Information of a customer is recorded differently in  different files.

So making Data as inconsistence is one of point to moving from File to DBMS

Integrity

Integrity refers to Enforcing data integrity ensures the quality of the data i.e. apply some logical rules again data

The problem of integrity is the problem of ensuring that the data in the database is accentuate.

The data values may need to satisfy some integrity constraints. For example  the balance field Value must be grater than 5000. We have to handle this through program code in file processing systems. But in database we can declare the integrity constraints along with definition itself.

In file processing it is not very easy to enforce rule on data.

Atomicity

Atomicity refers to having only one value i.e atomic value for given set of Data

As we know applications are developed independently in file processing systems leading to unplanned duplicate files. Duplication is wasteful as it requires additional storage space and changes in one file must be made manually in all files. This also results in loss of data integrity. It is also possible that the same data item may have different names in different files, or the same name may be used for different data items in different files.

It is difficult to ensure atomicity in file processing system.For example transferring  $100 from Account  A to account B.If a failure occurs during execution there could be situation like $100 is deducted from Account A and not credited in Account B.

Concurrent Access

Each application has its own private files with little opportunity to share data outside their own applications. A requested report may require data from several incompatible files in separate systems.

If multiple users are updating the same data  simultaneously it will result in inconsistent data state. In file processing system it is very difficult to handle this using program code. This results in concurrent access anomalies.

Security

Its very difficult to maintain and give proper secure mechanism in file processing system 

Enforcing Security Constraints in file processing system is very difficult as the application programs are added to the system in an ad-hoc manner.

Time consuming

File processing requires lot of time to do any operation on file data.

There is little opportunity to leverage previous development efforts. Each new application requires the developer to start from scratch by designing new file formats and descriptions also The preceding factors create a heavy program maintenance load.

As I have given lot of example hope you will really enjoy this post !!
In a way File processing has lots of drawback but DBMS overcome each of this ..

Hope you like it and enjoy learning !!

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