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