using arrow head as "Many" and single line as "One"
1 user can send many sms
1 sms can only belong to 1 user / This sms is unique to this particular user
I'm thinking that the UserSMS table is using a composite key but the 1:1 relationship confused me.
Example composite key (1st number user_id, 2nd number is sms_id)
(2,1) <==unique but wrong because sms ID is 1:1 relationship
I might even say that the sms id is a primary key of UserSMS table
Anyway is there a name for this type of things? Or is it even correct?
This post has been edited by aklo: 11 May 2012 - 08:21 PM