Relational Database Design 3rd Normal Form


  • There are some situations that
    • BCNF decomposition is not dependency preserving, but
    • efficiently checking the dependency violation on updates is important.
  • Thus, we define a weaker normal form called Third Normal Form (3NF).
    • 3NF allows some redundancy
    • But functional dependencies can be checked on individual relations without computing a join. There is always a lossless-join, dependency-preserving decomposition into 3NF.

$3^{rd}$ Normal Form