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normalization.txt
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2009-11-27
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1. List the primary key.
TrackingNum(PK)
2. List all the FDs.
TrackingNum -> EmpID
TrackingNum -> EmpName
TrackingNum -> OrderNo
TrackingNum -> ShipToAddr
TrackingNum -> ShippedDate
EmpID -> EmpName
OrderNo -> ShipToAddr
3. List all the update anomalies and provide an example of each.
1)insertion anomaly : when you insert a new employee,there is no TrackingNum of this new employee,
you have to update multiple record.
For example,when you want to insert the Name of 1234,because an EmpID may has
multiple orderNo,you have to update multiple record about name.
2)modification anomaly : when you modify a EmpID,because an employee disposed an order,
you have to modificate all orders disposed by this employee.
For example,when you want to modify the EmpID "2134" ,the new ID is "5678",
ou have to modificate all orders disposed by "2134".
3)deletion anomaly : when you delete an order,you may delete all information of a employee.
because a employee may deals with one order or many orders.
For example,
4. What normal form is the relation in? Explain
1)1NF: First Normal Form
1NF Definition: A relation schema is in 1NF, if the domain of every attribute allows a single atomic value.
That is, every cell in the table contains one and only one value.
TrackingNum(PK)
2. List all the FDs.
TrackingNum -> EmpID
TrackingNum -> EmpName
TrackingNum -> OrderNo
TrackingNum -> ShipToAddr
TrackingNum -> ShippedDate
EmpID -> EmpName
OrderNo -> ShipToAddr
3. List all the update anomalies and provide an example of each.
1)insertion anomaly : when you insert a new employee,there is no TrackingNum of this new employee,
you have to update multiple record.
For example,when you want to insert the Name of 1234,because an EmpID may has
multiple orderNo,you have to update multiple record about name.
2)modification anomaly : when you modify a EmpID,because an employee disposed an order,
you have to modificate all orders disposed by this employee.
For example,when you want to modify the EmpID "2134" ,the new ID is "5678",
ou have to modificate all orders disposed by "2134".
3)deletion anomaly : when you delete an order,you may delete all information of a employee.
because a employee may deals with one order or many orders.
For example,
4. What normal form is the relation in? Explain
1)1NF: First Normal Form
1NF Definition: A relation schema is in 1NF, if the domain of every attribute allows a single atomic value.
That is, every cell in the table contains one and only one value.
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