thinQmaster Virtual testing partner Adaptive practice exams that find your weak spots and drill them. Every answer explained. From $69
Enroll

thinQmaster

Find your exam

Five questions free, before you decide.

Step 1 · choose a vendor

In one of our camps? Your practice exams come with the tuition — they are on your study page already.

Data & Analytics · Advanced

Fourth Normal Form (4NF)

A table is in 4NF when it is in BCNF and has no non-trivial multivalued dependencies.

Definition

4NF addresses tables that store two or more independent multivalued facts about the same key, which causes combinatorial redundancy. The fix is to split each independent multivalued fact into its own table.

Example

Employee skills and employee languages stored together produce every skill-language combination; split them into two tables.

Exam tip

4NF deals with multivalued dependencies; 5NF deals with join dependencies. Both are rarely tested beyond definitions.

Related terms