Sunday, 13 January 2013

3NF reminder

Normalisation can be a mine field for some but I find that when I try to normalize data I don't have 3 key steps to get to 3NF, I just end up with a single operation that weeds all three things in one go.

I am conscious that 3 steps becomes more relevant for unfamiliar situations and for newbies but the descriptions I learned :

  1. Remove repeating groups
  2. Full functional dependency
  3. Transitive dependency
are pretty useless to succinctly describe the purpose - I've recently tried to narrate to a newbie what these mean and ended up with a less than brilliant explanation which made little sense to me let alone someone starting out.

However, I have recently I came across this meaningful summary :

  1. No repeating elements or groups of elements
  2. No partial dependencies on a concatenated key
  3. No dependencies on non-key attributes
which explain everything in a rememberable form

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