4 ms·

Third Normal Form

11 points by kamaraju 3y ago

karmakaze 3y ago
I don't consider this a good example of wanting 3NF. > A hypothetical example of a failure to meet third normal form would be a hospital database having a table of patients which included a column for the telephone number of their doctor. The phone number is dependent on the doctor, rather than the patient, thus would be better stored in a table of doctors. The negative outcome of such a design is that a doctor's number will be duplicated in the database if they have multiple patients, thus increasing both the chance of input error and the cost and risk of updating that number should it change (compared to a third normal form-compliant data model that only stores a doctor's number once on a doctor table). For instance having a single doctor row means that input from all a doctors patients overwrite each other's info about the doctor. Some may have special/private numbers or an incorrect one overwriting good data. This form only makes sense if doctors also use the system to provide their own canonical data.
- Nevermark 3y ago
  The point of the example was to illustrate normal form criteria, with a toy example, in an understandable way. Which it does. Not to demonstrate real world doctor-patient communication complexity, which could be complicated even further, I expect. I personally contact my doctor many ways, including through Discord, particular gaming world interfaces, or his wife. I recommend that everyone find a doctor with this kind of availability. Norm that! (Accounting for changes in mutual game world interest, marital status, etc.)
belter 3y ago
Preemptive Strike: First normal form - https://en.wikipedia.org/wiki/First_normal_form https://en.wikipedia.org/wiki/First_normal_form Second normal form - https://en.wikipedia.org/wiki/Second_normal_form https://en.wikipedia.org/wiki/Second_normal_form <call stack recursion...> Fourth normal form - https://en.wikipedia.org/wiki/Fourth_normal_form https://en.wikipedia.org/wiki/Fourth_normal_form Fifth normal form - https://en.wikipedia.org/wiki/Fifth_normal_form https://en.wikipedia.org/wiki/Fifth_normal_form Sixth normal form - https://en.wikipedia.org/wiki/Sixth_normal_form https://en.wikipedia.org/wiki/Sixth_normal_form

11 points by kamaraju 3y ago

I don't consider this a good example of wanting 3NF. > A hypothetical example of a failure to meet third normal form would be a hospital database having a table of patients which included a column for the telephone number of their doctor. The phone number is dependent on the doctor, rather than the patient, thus would be better stored in a table of doctors. The negative outcome of such a design is that a doctor's number will be duplicated in the database if they have multiple patients, thus increasing both the chance of input error and the cost and risk of updating that number should it change (compared to a third normal form-compliant data model that only stores a doctor's number once on a doctor table). For instance having a single doctor row means that input from all a doctors patients overwrite each other's info about the doctor. Some may have special/private numbers or an incorrect one overwriting good data. This form only makes sense if doctors also use the system to provide their own canonical data.

Nevermark 3y ago
The point of the example was to illustrate normal form criteria, with a toy example, in an understandable way. Which it does. Not to demonstrate real world doctor-patient communication complexity, which could be complicated even further, I expect. I personally contact my doctor many ways, including through Discord, particular gaming world interfaces, or his wife. I recommend that everyone find a doctor with this kind of availability. Norm that! (Accounting for changes in mutual game world interest, marital status, etc.)

belter 3y ago

Preemptive Strike: First normal form - https://en.wikipedia.org/wiki/First_normal_form https://en.wikipedia.org/wiki/First_normal_form Second normal form - https://en.wikipedia.org/wiki/Second_normal_form https://en.wikipedia.org/wiki/Second_normal_form <call stack recursion...> Fourth normal form - https://en.wikipedia.org/wiki/Fourth_normal_form https://en.wikipedia.org/wiki/Fourth_normal_form Fifth normal form - https://en.wikipedia.org/wiki/Fifth_normal_form https://en.wikipedia.org/wiki/Fifth_normal_form Sixth normal form - https://en.wikipedia.org/wiki/Sixth_normal_form https://en.wikipedia.org/wiki/Sixth_normal_form