Archives for: December 2004, 19
First 3 Rules of Data Normalization for Newbies - Part 1
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| Categories: Modeling The First Normal Form States: "All attributes are not repeated or must be single-valued"
In identifying whether a table is in its 1NF, consider this 3-points checklist:
1. Does a Primary Key exist?
2. Have you ensured that each attribute is in its basic form? Being in its basic form means that it is not derived
3. Have you ensured that the attribute is not repeated and considered single-valued?
Let us examine the following simple example :
1. Existence of a Primary Key: EMPLOYEE is uniquely identified by its attribute Employee_ID.
2. Verification that the attribute is in its basic form: The attribute Emp_Age is derived. Emp_Age is broken to its basic form, e.g. Emp_DateOfBirth.
3. Verification that the attribute is not repeating: In the example, Emp_Dependent, Emp_DependentNM, Emp_DependentDOB can be classified as repeating occurrences of EmployeeDependent. To make it in 1NF, move these to its own Entity.
The final result of the example will be:
Next blog will be on the 2NF. 
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