Thread: [SQLObject] Constraint for Time Series DB

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How can I ensure that there exists only one value for a given Date, ID pair?

- Luis

On Tue, Aug 10, 2010 at 02:16:26PM -0400, luis cota wrote:
> How can I ensure that there exists only one value for a given Date, ID pair?

   In general, by creating a unique index on (date, id) pairs; you can
create the index directly in SQL or in SQLObject.
   But in this particular case... you say ID - do you mean the primary key
for the table? Well, it's itself a unique key, you don't need to make
(date, id) pairs more unique.

Oleg.
-- 
     Oleg Broytman            http://phd.pp.ru/            ph...@ph...
           Programmers don't die, they just GOSUB without RETURN.

Correct - ID is referring to the primary key in the table.  If I insert a
data point(date, id, value), it is possible that I will update this point at
a later date.  I can manually check in code for existence of the date, id
pair, though I was wondering if there was another way to do this, or if
there was already a way to impose such a constraint.

- Luis

On Tue, Aug 10, 2010 at 2:37 PM, Oleg Broytman <ph...@ph...> wrote:

> On Tue, Aug 10, 2010 at 02:16:26PM -0400, luis cota wrote:
> > How can I ensure that there exists only one value for a given Date, ID
> pair?
>
>   In general, by creating a unique index on (date, id) pairs; you can
> create the index directly in SQL or in SQLObject.
>   But in this particular case... you say ID - do you mean the primary key
> for the table? Well, it's itself a unique key, you don't need to make
> (date, id) pairs more unique.
>
> Oleg.
> --
>     Oleg Broytman            http://phd.pp.ru/            ph...@ph...
>           Programmers don't die, they just GOSUB without RETURN.
>
>
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On Tue, Aug 10, 2010 at 04:15:38PM -0400, luis cota wrote:
> Correct - ID is referring to the primary key in the table.  If I insert a
> data point(date, id, value), it is possible that I will update this point at
> a later date.  I can manually check in code for existence of the date, id
> pair, though I was wondering if there was another way to do this, or if
> there was already a way to impose such a constraint.

   Then create an index.

> On Tue, Aug 10, 2010 at 2:37 PM, Oleg Broytman <ph...@ph...> wrote:
> 
> > On Tue, Aug 10, 2010 at 02:16:26PM -0400, luis cota wrote:
> > > How can I ensure that there exists only one value for a given Date, ID
> > pair?
> >
> >   In general, by creating a unique index on (date, id) pairs; you can
> > create the index directly in SQL or in SQLObject.
> >   But in this particular case... you say ID - do you mean the primary key
> > for the table? Well, it's itself a unique key, you don't need to make
> > (date, id) pairs more unique.

Oleg.
-- 
     Oleg Broytman            http://phd.pp.ru/            ph...@ph...
           Programmers don't die, they just GOSUB without RETURN.

Thread: [SQLObject] Constraint for Time Series DB

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