Re: OO and relation "impedance mismatch"
From: Kenneth Downs <firstinit.lastname_at_lastnameplusfam.net>
Date: Wed, 06 Oct 2004 21:05:18 -0400
Message-ID: <eo42kc.t0d.ln_at_mercury.downsfam.net>
>> mAsterdam wrote:
>>
>>
>> The current arbitrary feature for this case, which did not seem worth
>> mentioning in that post, is that you can specify a suffix to affix to the
>> columns in the child table. So for two foreign keys to the same table
>> one
>> is suffixed "_parent" and one suffixed "_child". This makes me really
>> uneasy though, I keep thinking "salesperson1", "salesperson2", etc...
Date: Wed, 06 Oct 2004 21:05:18 -0400
Message-ID: <eo42kc.t0d.ln_at_mercury.downsfam.net>
mAsterdam wrote:
> Kenneth Downs wrote: >
>> mAsterdam wrote:
>>
>>>Kenneth Downs wrote: >>>... >>> >>>>3. Enforce the arbitrary convention that a foreign key definition >>>> causes columns to be placed into the child table that correspond >>>> in name and type/precision/scale to the primary key of the >>>> parent. >>> >>><delurk> >>>Not the name. >>>It would exclude mutliple foreign keys between >>>two tables (ordinary? yes, very). You might want to use the role >>>name for each of them. >>></delurk>
>>
>> The current arbitrary feature for this case, which did not seem worth
>> mentioning in that post, is that you can specify a suffix to affix to the
>> columns in the child table. So for two foreign keys to the same table
>> one
>> is suffixed "_parent" and one suffixed "_child". This makes me really
>> uneasy though, I keep thinking "salesperson1", "salesperson2", etc...
> > While I was thinking account_from, account_to, > account_provision, account_costs, etc.
Yes, yours is appropriate, if I understand your use of account_from and account_to. I don't understand account_provision and account_costs, are all four columns in one table? If so, what are they?
But salesperson1..n is not usually appropriate. Haven't figured out if I can protect against one while allowing another, but also haven't thought about it that hard. At the moment the loophole is open.
-- Kenneth Downs Use first initial plus last name at last name plus literal "fam.net" to email meReceived on Thu Oct 07 2004 - 03:05:18 CEST