Relational database Normalization

function dependencies:

For relational mode R (U)

· X-->y Y∈X trivial function dependent a1,a2-->a2

· X-->y Y∉X non-trivial function dependent a1,a2-->a3

· X-->y x any true subset X '-\->yFull function DependencyA1,a2-->a3 a1-\->A3a2-\->a3

· X-->y Y Nofull function dependent xPartial function DependencyA1,a2-->a3 a1-\->a3a2-->a3

· X-->y y-->z y-\->x Z∉The X-Z transfer function relies on X >a1,a2

Paradigm :

1NF: The properties of each relationship of R in the relational pattern are non-divided data items.

Each attribute in R is a single and indivisible

2NF: for 1NF, each non-primary attribute is completely dependent on the candidate key.

Eliminate partial function dependencies on primary properties for non-primary properties

3NF: If 2NF is satisfied, all non-primary properties in the relational mode R (U,F) do not have transitive dependencies on the primary attribute.

Eliminate transitive dependencies between non-primary and primary attributes

Relational database Normalization