Fifth Normal Form (5NF)

5NF (fifth normal form) is also known as item joining paradigm. If a relation is 4NF, it is in fifth normal form (5NF) and does not losslessly decompose into smaller tables.

You can also consider the relationship to be 5NF if the candidate key is . Every connection dependency in it is implicit.

Example

The following relationship violates normalized fifth normal form (5NF) -

David Java E145 ##John Jamie Emma ##The above relationship can be decomposed into the following three tables; therefore, it is not in 5NF -

EmpName强>	EmpSkills	##EmpJob(Assigned work)
JavaScript	E146
jQuery	E146 td>
p> Java	E147	p>

##EmpName JavaScript jQuery Java

EmpSkills	David
Java	##John
	##Jamie
	Emma
	##The following are the relationships showing the assignments to Each employee’s job- td>

##EmpName

EmpJob ##David

	E145
John	E146
Jamie	E146
Emma	E147
The following are the skills relevant to the assigned job-

p>

EmpSkills

EmpJob ##Java

##Java	E145
JavaScript	E146
jQuery	E146
E147
Our connection dependencies-	{(EmpName, EmpSkills), (EmpName, EmpJob), (EmpSkills, EmpJob)}

The above relationships have connection dependencies properties, so they do not belong to 5NF. This means that the connection relationship of the above three relationships is equal to our original relationship

.

The above is the detailed content of Fifth Normal Form (5NF). For more information, please follow other related articles on the PHP Chinese website!