The file system’s structure makes it difficult to combine data from multiple sources, and its lack of security renders
the file system vulnerable to security breaches. The organizational structure promotes the storage of the same basic
data in different locations. (Database professionals use the term islands of information for such scattered data locations.)
The dispersion of data is exacerbated by the use of spreadsheets to store data. In a file system, the entire sales
department would share access to the SALES data file through the data management and reporting programs created
by the DP specialist. With the use of spreadsheets, each member of the sales department can create his or her own
copy of the sales data. Because data stored in different locations will probably not be updated consistently, the islands
of information often contain different versions of the same data. For example, in Figures 1.5 and 1.6, the agent
names and phone numbers occur in both the CUSTOMER and the AGENT files. You only need one correct copy of
the agent names and phone numbers. Having them occur in more than one place produces data redundancy. Data
redundancy exists when the same data are stored unnecessarily at different places.
The file system’s structure makes it difficult to combine data from multiple sources, and its lack of security renders
the file system vulnerable to security breaches. The organizational structure promotes the storage of the same basic
data in different locations. (Database professionals use the term islands of information for such scattered data locations.)
The dispersion of data is exacerbated by the use of spreadsheets to store data. In a file system, the entire sales
department would share access to the SALES data file through the data management and reporting programs created
by the DP specialist. With the use of spreadsheets, each member of the sales department can create his or her own
copy of the sales data. Because data stored in different locations will probably not be updated consistently, the islands
of information often contain different versions of the same data. For example, in Figures 1.5 and 1.6, the agent
names and phone numbers occur in both the CUSTOMER and the AGENT files. You only need one correct copy of
the agent names and phone numbers. Having them occur in more than one place produces data redundancy. Data
redundancy exists when the same data are stored unnecessarily at different places.
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