Re: Redefining an existing Table Schema for Foreign Key Constraint - Question
От | Harald Fuchs |
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Тема | Re: Redefining an existing Table Schema for Foreign Key Constraint - Question |
Дата | |
Msg-id | pumygbmqb6.fsf@srv.protecting.net обсуждение исходный текст |
Ответ на | Redefining an existing Table Schema for Foreign Key Constraint - Question (Brian714 <bndang@uci.edu>) |
Список | pgsql-general |
In article <20081106213736.GB25016@tamay-dogan.net>, Michelle Konzack <linux4michelle@tamay-dogan.net> writes: > Hallo Harald, > Am 2008-11-03 13:41:52, schrieb Harald Fuchs: >> In article <20294223.post@talk.nabble.com>, >> Brian714 <bndang@uci.edu> writes: >> > Customers Table >> > id:integer -- primary key >> > first_name:varchar(50) >> > last_name:varchar(50) >> > cc_id:integer references Creditcards.id >> > address:varchar(200) >> > email:varchar(50) >> > password:varchar(20) >> This is the usual 1:n relationship, but I think you got it backwards. >> There are two questions to ask: >> 1. Are there customers with more than one credit card? > This could be a problem for the above table... >> 2. Are there credit cards owned by more than one customer? > CreditCards are personaly and sometimes (in France) I need an ID card to > prove, that I am the holder... > So how can one credit card can have more then one owner? That's exactly why I told you "I think you got it backwards". You need a cust_id column in your CreditCards table, not a cc_id column in your Customers table.
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