In this page you will see a basic database normalization example, transforming BCNF table into a 4NF one(s).

The next table is in the BCNF form, convert it to the 4th normal form.

language

skill Employee

French

electrical

Jones

German

electrical

Jones

French

mechanical

Jones

German

mechanical

Jones

Spanish

plumbing

Smith

The above table does not comply with the 4th normal form, because it has repetitions like this:

A

X

Jones

B

Y

Jones

So this data may be already in the table, which means that it’s repeated.

X

B

Jones

Y

A

Jones

To transform this into the 4th normal form (4NF) we must separate the original table into two tables like this:

skill

employee

electrical

Jones

mechanical

Jones

plumbing

Smith

And

language

employee

French

Jones

German

Jones

Spanish

Smith