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information is frequently needed, a new file structured on educational background
key will have to be created along with a new program to process this file.
2. Data redundancy. In file-oriented approach, the same data items are often
included in many different files. For instance, in the above example of creating a
new file structured on educational background key, the new file will also have
several of the data items stored in the first employee file. Similarly, suppose a
bank uses the file-oriented approach for storing its customers data, and it
maintains separate customer files for its various types of services such as savings
accounts, term deposits, and loan accounts. In this case, a great deal of redundant
data for a bank customer (such as home address, age, occupation, and
identification information) may be contained in multiple files. Repetition of the
same data items in more than one file is known as data redundancy. It leads to
increase in the cost of data entry and data storage. It also leads to data integrity
problem described below.
3. Data integrity problem. Data integrity is the consistency of the data in all files.
That is, in file-oriented approach, when some change occurs in a data item, every
file, which contains that field, should be updated to reflect the change for
consistency. For instance, in our example in which a bank maintains separate
customer files for each type of account, when a customer moves to a new address,
his/her address field must be updated in all the customer files in which this
customer's record is present. Integrity of data is necessary to avoid confusions that
may result when one file is updated while others are not. For example, in case of a
change in a data item, if all the files containing the data item are not updated
correctly, there may be frequent discrepancies among reports produced fro:
different files, causing confusion.
4. Lack of "program/data independence. In file-oriented approach, the application
programs usually contain data format statements that precisely define each data
field to be processed. This often results in different files having the same data item
stored using different data formats. Data dependence occurs when, the data is
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- Spring '14