Computer Sciene of Udayana State University

April 26, 2009

Second Normal Form (2NF)

Filed under: Computer Science — ignaga @ 2:13 AM
  • Based on concept of full functional dependency:

A and B are attributes of a relation,

B is fully dependent on A if B is functionally dependent on A but not on any proper subset of A.

  • 2NF – A relation that is in 1NF and every non-prime attribute is fully functionally dependent on the primary key.

Prime attribute: An attribute that is member of the primary key K

Example: EMP_PROJ(SSN, Pnum, Hours, Ename, Pname, Ploc)

{SSN,Pnum}–>Hours, SSN–>Ename, Pnum–>{Pname, Ploc}

* Relation is not in 2NF

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