Fourth Normal Form

Fourth normal form (4NF) is a normal form used in database normalization. Introduced by Ronald Fagin in 1977, 4NF is the next level of normalization after Boyce–Codd normal form (BCNF). Whereas the second, third, and Boyce–Codd normal forms are concerned with functional dependencies, 4NF is concerned with a more general type of dependency known as a multivalued dependency. A Table is in 4NF if and only if, for every one of its non-trivial multivalued dependencies X Y, X is a superkey—that is, X is either a candidate key or a superset thereof.

Read more about Fourth Normal Form:  Multivalued Dependencies, Example, 4NF in Practice

Famous quotes containing the words fourth, normal and/or form:

    What, to the American slave, is your Fourth of July? I answer: A day that reveals to him, more than all other days in the year, the gross injustice and cruelty to which he is the constant victim. To him your celebration is a sham.
    Frederick Douglass (c.1817–1895)

    As blacks, we need not be afraid that encouraging moral development, a conscience and guilt will prevent social action. Black children without the ability to feel a normal amount of guilt will victimize their parents, relatives and community first. They are unlikely to be involved in social action to improve the black community. Their self-centered personalities will cause them to look out for themselves without concern for others, black or white.
    James P. Comer (20th century)

    Since the Greeks, Western man has believed that Being, all Being, is intelligible, that there is a reason for everything ... and that the cosmos is, finally, intelligible. The Oriental, on the other hand, has accepted his existence within a universe that would appear to be meaningless, to the rational Western mind, and has lived with this meaninglessness. Hence the artistic form that seems natural to the Oriental is one that is just as formless or formal, as irrational, as life itself.
    William Barrett (b. 1913)