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From "Peter S. Hamlen" <pham...@mail.com>
Subject OT: Are primary keys always autogenerated? (Was RE: How to set thePK manually)
Date Tue, 11 Feb 2003 20:54:40 GMT
Justin,

You are correct.  I was referring specifically to Torque, which treats
primaryKey columns as auto-generated (at least, this is my understanding
having perused the code.)   

When I have tables where I don't want auto-generated keys, I have
generally avoided stating that the column is a "PrimaryKey" - instead, I
create a <unique> constraint on the table instead.  And then, of course,
you have to have some mechanism for setting the column value to a unique
key.

Nonetheless, you're right that, in the general world of schema design,
there is no requirement that a primaryKey be a number or that it be
auto-generated.  But I'll go out on a limb and say that I believe it's a
'best-practice'!  Others may disagree.  :)


-Peter


On Mon, 2003-02-10 at 18:20, Campbell, Justin wrote:
> Peter -
> 
> I would argue whether or not primary keys are auto-generated by definition.
> This statement is true of "identity" (SQL Server terminology used here;
> a.k.a. AutoNumber, ID, etc.) columns. However, a primary key can consist of
> one or more non-identity columns (e.g. a varchar(50) value).
> 
> Personally, all my primary keys *are* identity columns (as this makes it
> easier to isolate the actual "key" value and eases changes to the key
> combination in the future), but this is not necessary (nor even recommended
> by some schools of thought in DB schema design).
> 
> Just thought I'd clarify for folks out there as this statement may cause
> confusion among the uninitiated.
> 
> Best of luck.
> 
> - Justin
> 
> -----Original Message-----
> From: Peter S. Hamlen [mailto:phamlen@mail.com]
> Sent: Monday, February 10, 2003 6:22 PM
> To: Turbine Torque Users List
> Subject: Re: how to set the PK manually?
> 
> 
> Marc,
> 
> My understanding is that you cannot accomplish this if it's a primary
> key.  Primary keys, by their definition, are generated automatically so
> that there aren't any duplicates.
> 
> As Justin Campbell mentioned in a previous email, you might want to have
> Table B have a foreign-key to table A (that's how most of us accomplish
> this.)
> 
> The other option (if you're really talking about "extending") is to add
> the columns for B into table A - and add a "type" column that indicates
> whether the object in the table is of type A or B.
> 
> For example:
> 
> <table name="PaymentPlans">
>   <column name="Type" description="Annual or Monthly"/>
>   <column name="MonthlyBillDate" description="Only used for Monthly
> types"/>
>   <column name="AnnualBillDate" description="Only used for annual
> plans"/>
>   <column name="AmountDue" type="INTEGER"/>
>  </table>
> 
> You can find more information about this in the "Inheritance" section of
> Torque.
> 
> -Peter
> On Thu, 2003-02-06 at 13:20, Marc Lustig wrote:
> > Hi,
> > 
> > I'm creating a new instance (row) and set the PK to a certain value.
> > (I need to do this because this table B extends another table A, so the PK
> > in table B must be the same as in table A.)
> > 
> > My defaultIdMethod is "idbroker":
> > <database defaultIdMethod="idbroker"...
> > 
> > And to make torque not generating the PK I set idMethod="none":
> > <table name="B" idMethod="none">
> > 
> > Problem is when I trigger save() torque still generates a new PK and
> assigns
> > it. How comes that?
> > How can I make torque not to auto-generate a new primary key when save()
> is
> > called?
> > 
> > Thanks!
> > 
> > Marc
> > 
> > 
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> > 
> 
> 
> 
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