# Joint Dependency and Multivalued Dependency

1) What is meant by Joint DEPENDENCY in normalization?
2) What is a MULTIVALUED DEPENDENCY? Explain.

#### sravan

• Dec 29th, 2006

u see.....joint dependency means that.........when u decompose tables those decomposed table should satisfy JOIN dependency ...ie., when they are joined they should make the original table without any conflicts.......MULTIVALUED DEPENDENCIES means the fourth normal form.......when a table is in such a way that t1(a)=t2(a)=t3(a)=t4(a);t1(b)=t2(b) and t3(b)=t3(4);t1(c)=t3(c) and t2(c)=t4(c);this can be decomposed again with the 4th normal form.....

#### Athira.m.m

• Oct 12th, 2015

You see joint dependency means that when you decompose tables those decomposed table should satisfy JOIN dependency ie., when they are joined they should make the original table without any conflicts MULTIVALUED DEPENDENCIES means the fourth normal form when a table is in such a way that
t1(a) = t2(a) = t3(a) = t4(a);
t1(b) = t2(b) and t3(b) = t3(4);
t1(c) = t3(c) and t2(c) = t4(c);
this can be decomposed again with the 4th normal form.

#### shivakumar

• Jan 12th, 2016

When you decompose a relation into sub relations and when you assembled those sub relations it should result in original loss-less relation. Such dependency is called join dependency. Example relation R is decomposed into r1, r2.....rn than when you assembled them it should equals to R (without any loss).  