Thread: [SQLObject] Constraint for Time Series DB
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From: luis c. <lo....@gm...> - 2010-08-10 18:16:28
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How can I ensure that there exists only one value for a given Date, ID pair? - Luis |
From: Oleg B. <ph...@ph...> - 2010-08-10 18:37:58
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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. |
From: luis c. <lo....@gm...> - 2010-08-10 20:15:48
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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. > > > ------------------------------------------------------------------------------ > This SF.net email is sponsored by > > Make an app they can't live without > Enter the BlackBerry Developer Challenge > http://p.sf.net/sfu/RIM-dev2dev > _______________________________________________ > sqlobject-discuss mailing list > sql...@li... > https://lists.sourceforge.net/lists/listinfo/sqlobject-discuss > |
From: Oleg B. <ph...@ph...> - 2010-08-10 21:06:12
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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. |