Why We Need DBMS ?
The advantages of using a DBMS fall into
three main categories.
• Proper maintenance of the data GB
• Providing access to data
• Maintaining security of the data
1)Proper Maintenance of the Data
The users must be able to trust that the
data is accurate and up to date. Inconsistency should be avoided and redundancy should be minimized. Redundancy
occurs when the same information is kept in a variety of places. Inconsistency comes when data are changed in one of
those locations and not changed in another. Most database systems provide for integrity constraints that must be
followed. The DBMS is the key to enforcing these characteristics within the database. Each DBMS may manage the data in different ways, but they all are careful to address such data issues.
Example:-
In a particular organization, customer names and addresses are kept in one database for the sales department and another database for
the billing department. What inconsistency might result from this redundancy?
When a sales person is taking an order, the customer reports a change in address. The sales person might update the
record in the sales department. However, when the bill is prepared, it is sent to the old address because the address was not changed in that database.
2)Providing Access to Data
The data are usually shared by a variety of users and programs. Both storage of and
access to data should be easy and quick. Concurrent support for all kinds of transactions, both interactive and
programmed queries, must be provided by the DBMS. The interactive queries should not have to wait for the application
programs to finish. Basically, the data should be accessible precisely when required. It would be unacceptable for the
users to wait even a day while the database is updated and checked. The job of the DBMS is to allow for speedy access for all the necessary users while still using proper maintenance procedures.
Another issue surrounding access is the ability to find a particular piece of information from the large amount of data
stored. The DBMS must contain flexible methods to access each item in the database while allowing for speedy searches
throughout the database to find that item.
3)Maintaining Security of the Data
The DBA is usually the person responsible for the security of the data. Unauthorized access must be prevented, and a
variety of levels of permission must be granted to users. Tools are provided for the DBA to enforce all security
procedures and meet all the conflicting requirements that arise when many people must access the same database. If two
separate users are accessing a particular table at the same time, the DBMS must not allow them both to make conflicting changes. Such safeguards are part of all systems. The DBMS also provides the tools for easy backup and recovery in case of system failures.
Example:-
Make a list of all the databases you can think of where your name and financial information are kept. How can you check the accuracy
of this data?
Information about you is stored by your employer, your school, possibly your religious organization, the government
and any banks or credit companies. You can check the accuracy of many of these locations by asking for a credit report
or current statement. Many localities have laws requiring schools and government agencies to allow you to see and
correct personal information. You will never know if the information is wrong if you don't check it yourself.
It might also be helpful to specify situations when one might not want to use a DBMS. Sometimes these systems result
in unnecessary costs when traditional file processing would work just as well. If only one person maintains the data and
that person is not skilled in designing a database, the resulting product might also take more time and be less efficient.
When you are designing a database, as with any other system, remember that a simple, clear strategy is usually more
easily maintained than a complex, confusing design.
three main categories.
• Proper maintenance of the data GB
• Providing access to data
• Maintaining security of the data
1)Proper Maintenance of the Data
The users must be able to trust that the
data is accurate and up to date. Inconsistency should be avoided and redundancy should be minimized. Redundancy
occurs when the same information is kept in a variety of places. Inconsistency comes when data are changed in one of
those locations and not changed in another. Most database systems provide for integrity constraints that must be
followed. The DBMS is the key to enforcing these characteristics within the database. Each DBMS may manage the data in different ways, but they all are careful to address such data issues.
Example:-
In a particular organization, customer names and addresses are kept in one database for the sales department and another database for
the billing department. What inconsistency might result from this redundancy?
When a sales person is taking an order, the customer reports a change in address. The sales person might update the
record in the sales department. However, when the bill is prepared, it is sent to the old address because the address was not changed in that database.
2)Providing Access to Data
The data are usually shared by a variety of users and programs. Both storage of and
access to data should be easy and quick. Concurrent support for all kinds of transactions, both interactive and
programmed queries, must be provided by the DBMS. The interactive queries should not have to wait for the application
programs to finish. Basically, the data should be accessible precisely when required. It would be unacceptable for the
users to wait even a day while the database is updated and checked. The job of the DBMS is to allow for speedy access for all the necessary users while still using proper maintenance procedures.
Another issue surrounding access is the ability to find a particular piece of information from the large amount of data
stored. The DBMS must contain flexible methods to access each item in the database while allowing for speedy searches
throughout the database to find that item.
3)Maintaining Security of the Data
The DBA is usually the person responsible for the security of the data. Unauthorized access must be prevented, and a
variety of levels of permission must be granted to users. Tools are provided for the DBA to enforce all security
procedures and meet all the conflicting requirements that arise when many people must access the same database. If two
separate users are accessing a particular table at the same time, the DBMS must not allow them both to make conflicting changes. Such safeguards are part of all systems. The DBMS also provides the tools for easy backup and recovery in case of system failures.
Example:-
Make a list of all the databases you can think of where your name and financial information are kept. How can you check the accuracy
of this data?
Information about you is stored by your employer, your school, possibly your religious organization, the government
and any banks or credit companies. You can check the accuracy of many of these locations by asking for a credit report
or current statement. Many localities have laws requiring schools and government agencies to allow you to see and
correct personal information. You will never know if the information is wrong if you don't check it yourself.
It might also be helpful to specify situations when one might not want to use a DBMS. Sometimes these systems result
in unnecessary costs when traditional file processing would work just as well. If only one person maintains the data and
that person is not skilled in designing a database, the resulting product might also take more time and be less efficient.
When you are designing a database, as with any other system, remember that a simple, clear strategy is usually more
easily maintained than a complex, confusing design.
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