database - What's the difference between fourth and fifth normal form? -

They look like me, especially when it comes to decomposition, what exactly is the difference?

A relationship is in R4 NF iff, every non-transitional mutual dependency, J, satisfied by R R is contained with the key of the candidates, where J is dependent on any 2 estimates of R (R1, R2).

A relation is in R5 NF. Iff is dependent on the integration of the denominational R, R, R, with the key of the candidate's candidates, where J in R (R1, R2, .. RN) depends on any of the n estimates. .

In other words, 4 NFs are very much like 5 NFs, but only 2-part dependency under 4-NF is relevant, whereas in all N-Part to meet the requirements of 5 NF The dependence involved in the N-Part should be considered. Therefore, 4 NF is not very important and exists only for historical reasons, that is because it was first discovered and published. Practically, this is probably easier to ignore 4NF because 5NF is more useful and important.