Changes between Version 20 and Version 21 of Normalization

Timestamp:

04/27/26 02:37:50 (5 days ago)

Author:

221296

Comment:

--

Normalization

@@ -270 +270 @@
 
 == Check for 3NF (and decomposition)
-Now we look for transitive dependencies inside the produced relations.
+Now we look for transitive dependencies inside the relations obtained after the 2NF decomposition.
 
 === Typical transitive issues from the ER
-* In Clients(client_id, user_id, …), we have client_id → user_id, but user descriptive attributes are stored in Users, so no transitive dependency remains inside Clients.
+* In Payment(payment_id, user_id, subscription_id, amount), we have:
+  payment_id → subscription_id
+  subscription_id → user_id, plan_id, start_date, end_date, subscription_status.
+  Because subscription details are stored in UserSubscription, they should not be repeated in Payment. Payment keeps only payment_id, user_id, subscription_id and amount, so no transitive dependency remains inside Payment.
+ 
 * In Listings(listing_id, admin_id, animal_id, …), we have listing_id → admin_id and globally admin_id → user_id, but user attributes are stored in Users, not in Listings, so no transitive dependency remains inside Listings.
 * In VetClinicApplications(application_id, clinic_id, …), we have application_id → clinic_id and clinic_id determines clinic attributes, but those attributes are stored in VetClinics, not in VetClinicApplications, so no transitive dependency remains there either.