Dbms (Obms & Oracle 91)
MC0067 - 01
Marks - 40 DBMS (OBMS & ORACLE 91)
1. Write a note on File based system/ Data base system
Solution:
File-Based Systems:
Conventionally, Before the database Systems evolved , data in the software’s Systems was stored in and represented using flats files.
Drawbacks of File-Based Systems:
File - Based Systems
[pic]
As shown in the figure, in a file-based system, different programs in the same application may be interacting with different private data files. There is no system enforcing any standardized control on the organization and structure of these data files.
• Data Redundancy and Inconsistency
Since data resides in different private data files, there are chances of redundancy and resulting inconsistency. For example, in the above example shown, the same customer can have a savings account as well as a mortgage loan. Here the customer details may be duplicated since the programs for the two functions store their corresponding data in two different data files. This gives rr.>e to redundancy in the customer's data. Since the same data is stored in two files, inconsistency arises if a change made in the data in one file is not reflected in the other.
• Unanticipated Queries
In a file-based system, handling sudden/ad-hoc queries can be difficult, since it requires changes in the existing programs.
• Data Isolation
Though data used by different programs in the application may be related, they reside in isolated data files.
• Concurrent Access Anomalies
In large multi-user systems the same file or record may need to be accessed by multiple users simultaneously. Handling this in file-based systems is difficult.
• Security Problems
In data-intensive applications, security of data is a major concern. Users should be given access only to required data and not the whole database. In a file-based system, this can be handled only by additional programming in each application.
2. What are the Roles and
Marks - 40 DBMS (OBMS & ORACLE 91)
1. Write a note on File based system/ Data base system
Solution:
File-Based Systems:
Conventionally, Before the database Systems evolved , data in the software’s Systems was stored in and represented using flats files.
Drawbacks of File-Based Systems:
File - Based Systems
[pic]
As shown in the figure, in a file-based system, different programs in the same application may be interacting with different private data files. There is no system enforcing any standardized control on the organization and structure of these data files.
• Data Redundancy and Inconsistency
Since data resides in different private data files, there are chances of redundancy and resulting inconsistency. For example, in the above example shown, the same customer can have a savings account as well as a mortgage loan. Here the customer details may be duplicated since the programs for the two functions store their corresponding data in two different data files. This gives rr.>e to redundancy in the customer's data. Since the same data is stored in two files, inconsistency arises if a change made in the data in one file is not reflected in the other.
• Unanticipated Queries
In a file-based system, handling sudden/ad-hoc queries can be difficult, since it requires changes in the existing programs.
• Data Isolation
Though data used by different programs in the application may be related, they reside in isolated data files.
• Concurrent Access Anomalies
In large multi-user systems the same file or record may need to be accessed by multiple users simultaneously. Handling this in file-based systems is difficult.
• Security Problems
In data-intensive applications, security of data is a major concern. Users should be given access only to required data and not the whole database. In a file-based system, this can be handled only by additional programming in each application.
2. What are the Roles and