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Answer
3: The same piece of
information may be stored in two or more files. For example –
the particular of an individual who may be a customer or an
employee may be stored in two or more files. Some of these information
may be changing., such as the address, the pay drawn, etc. it is
therefore quite possible that while the address in the master file for
one application has been updated the address in the master file for
one application has been updated the address in the master file
for another application may have not been. It may not also be easy for
the computer based system to even find out as to in how
many files the repeating items such as the address if occurring.
The solution
there for is to avoid this data redundancy and the keeping of multiple
copies of the same information and replace it by a system where the
address is stored at just one place physically, and is accessible to
all applications from this itself. Reduction
of Redundancies: centralized control of data by the DBA avoids
unnecessary duplication of data and effectively reduce the total
amount of data in a large mass of data. Another advantage of avoiding
duplication is the elimination of the inconsistencies that tend
to be present in redundant data files. Any redundancies that exist in
the DBMS are controlled and system ensures that these multiple copies
are consistent.
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