« First 3 Rules of Data Normalization for Newbies - Part 2First 3 Rules of Data Normalization for Newbies - Introduction »

First 3 Rules of Data Normalization for Newbies - Part 1

12/19/04 | by Clarise | 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 :
1NF_sample1

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. :)

Send feedback »
 

No feedback yet

June 2019
Mon Tue Wed Thu Fri Sat Sun
          1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
 << <   > >>
This blog contains thoughts that range from non-technical to technical. Its name is derived from "Yakity Blah Blah" a column I once had that discussed a cornucopia of ideas. Who am I? I'm Clarise Z. Doval Santos, providing Project Management and Technical Leadership for data management and analytic, data science, IoT and sensor analytics ecosystems 37.652951177164 -122.490877706959

Search

  XML Feeds

open source blog tool