4.2. 1st Normal Form

• Atomic Values

• Unique Identifiers (rows uniquely identified by PRIMARY KEY)

• Entries in a column are same type

4.2.1. 1st Normal Form

• A cell must never contain more than one value

• Each row must be unique

• Each column name must be unique

• There must be no repeating groups

4.2.2. Atomic Values

• Cell with single values

• A cell must never contain more than one value

• Each value needs to be in its own column

Table 4.4. Assignments (problem)

name	role
Melissa Lewis	Commander
Mark Watney	Botanist
Rick Martinez	Pilot

Note that in this example astronaut's firstname and lastname is in the same column (name).

Table 4.5. Assignments (solution)

firstname	lastname	role
Melissa	Lewis	Commander
Mark	Watney	Botanist
Rick	Martinez	Pilot

Figure 4.4. A cell must never contain more than one value (each value needs to be in its own column) Image credits: [1]

4.2.3. Unique Rows

• Each row must be unique

• One column, or combination of columns must uniquely identify a row

• Also known as PRIMARY KEY

Table 4.6. assignments (problem)

firstname	lastname
Melissa	Lewis
Mark	Watney
Mark	Watney

Note, that this in problematic example we can have duplicate names, for example there could be more than one Mark Watney in the world.

Table 4.7. assignments (solution)

id (PK)	firstname	lastname
1	Melissa	Lewis
2	Mark	Watney
3	Mark	Watney

Now, even if we have two Mark Watneys, each of them will have a unique identifier (id).

Figure 4.5. Each row must be unique (one column, or combination of columns must uniquely identify a row also known as PRIMARY KEY). Image credits: [1]

4.2.4. Unique Column Names

• Each Column Name Must be unique

Table 4.8. assignments (problem)

name	year	name
Melissa Lewis	2035	Ares3
Mark Watney	2035	Ares3
Rick Martinez	2035	Ares3

Some column names are very (such as name) to the point, that there could be several independent columns which we can call by name. Each column should have unique name.

Table 4.9. assignments (solution)

astronaut	year	mission
Melissa Lewis	2035	Ares3
Mark Watney	2035	Ares3
Rick Martinez	2035	Ares3

Figure 4.6. Each column name must be unique. Image credits: [1]

4.2.5. No Repeating Groups

• There must be no repeating groups

Table 4.10. Assignments (problem)

astronaut	year1	mission1	year2	mission2
Melissa Lewis	2031	Ares1	2035	Ares3
Mark Watney	2031	Ares1	2035	Ares3
Rick Martinez	2031	Ares1	2035	Ares3

Figure 4.7. There must be no repeating groups. Image credits: [1]

4.2.6. Recap

Figure 4.8. If both Atomic Values and Unique Identifiers rules are applied the database achieved 1st Normal Form. Image credits: [1]

4.2.7. References

[1] (1,2,3,4,5)

Lowgren, Jesper. Database Normalization 1NF 2NF 3NF. Year: 2021. Retrieved: 2022-02-05. URL: https://www.youtube.com/watch?v=SK4H5tTT6-M