Introduction: Visitors can fill reports on my website. Those report can either be filled by a legalPerson or a naturalPerson.

Constraint: I don't like empty fields and I would like to normalize as much as possible my database. Hence, I have those relations:

Database model

Question: For these kind of optional relations, should I add the field notifier_type (we could call it a criteria field) in Report Object? I mean I can obtain a close result with:

if($this->getNaturalPerson) { 
    $notifierType = 'naturalPerson';
} ...

The only drawback would be that I can't query on notifier_type if it's not in DB.

What is the best practice here?

  • The way you have your FKs, a person (normal or legal) can file only one report and never more than one. I doubt that is your intention. Right? Jul 30, 2014 at 12:54

1 Answer 1


I'd put person_id as second field of Report and get rid of notifier_type. Then create a relation persons (persona?) with id field, then make foreign key from Report.person_id to persons.id.

This relation persons (persona?) would have all of fields from both your legal- and naturalPerson relations, plus one additional - person_type. You would have NULLs when a field would be not applicable for given type of person (namely legal_Statut would be NULL for natural person and birthday would be NULL for legal person).

I would then exclude headquarters_address and home_address and make additional relation addresses with person_id field - again, foreign key to persons.id. You would then have a possibility of assigning multiple addresses to persons, mark them as current or previous, whatever you wish. That's what I would do.

EDIT: Visualization

enter image description here

  • Thanks for your answser. However your solution doesn't appear 3NF compliant. Each field on Report are not dependent only on the PrimaryKey -> if the legal persons field are n/a, the naturalperson field will be filled and the inverse is true.
    – Xavier13
    Jul 30, 2014 at 6:36
  • Look at the picture and tell me what NOT depents on what, because I don't think I understand you, or you don't understand me.
    – Kitet
    Jul 30, 2014 at 12:31

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