by 
tt010101
ANSWERS: 2
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The duplication and repitition of data in a database, compromising the data integrity and decreasing efficiency.
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The Order relation has data redundancy problems that can cause more storage to be used than necessary, by looking at the example below we can find out how these problems can occur. The Order relation experiences Insertion anomalies when we do not enter in the attributes associated with the OrderNum correctly. In the example (above) one of the orders has been spelt incorrectly and has been recorded as a separate order in the database (where the OrderNum = 010). Also because each CD has a unique number, the same order would have multiple rows determining the CD’s that they have bought. If we were to type the CustID, OrderDate and CDNum incorrectly we would have a problem since all of these attributes correspond to OrderNum. Thus a new tuple needs to be consistent with existing tuples.
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