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From "Bernt M. Johnsen" <Bernt.John...@Sun.COM>
Subject Re: Using/Adressing a "row number" in a SELECT query
Date Fri, 17 Feb 2006 13:25:28 GMT
>>>>>>>>>>>> Sylvain RICHET wrote (2006-02-17 11:55:37):
> Thanks Legolas,
> 
> ... but limiting the fetch size by JDBC API supported methods (setFetchSize)
> implies that i have already loaded ALL records from database, no ?

setFetchSize is an optimization hint to the driver/database and will
not affect the result.

setMaxRows will limit the number of rows in the resulting
resultset. And any decent JDBC-driver will limit the number of rows
"loaded" from the database (in client/server mode, that is).

> 
> However, the datas persisted in my DERBY database concern logging. It means
> that i would have to get thousands of records.
> 
> On 2/17/06, Legolas Woodland <legolas.w@gmail.com> wrote:
> >
> > Sylvain RICHET wrote:
> >
> > Hi everyone,
> >
> > In a selection statement, i would like to get blocks of records.
> > Thus, i need to filter records by a "row number", directly at the SELECT
> > level.
> >
> > It seems that the way to address a row number is not (SQL) standard.
> > (different "proprietary" implementations)
> >
> > In Oracle, there is the "rowid".
> > In MySQL, the "LIMIT" clause can do it.
> > In SQL Server, i think there is the "ROW_NUMBER() OVER..."
> > In DB2 (on AS/400) , there is the "RRN" (Relative Record Number)...
> >
> > What about Derby database ?
> > How is it implemented on this server ?
> >
> > I know i could use
> >
> > Thanks in advance.
> >
> > Derby sql does not has any facilities for limiting number of rows in
> > select statement.
> > you can just limit the fetch size in JDBC resultSets.
> >
> >

-- 
Bernt Marius Johnsen, Database Technology Group, 
Staff Engineer, Technical Lead Derby/Java DB
Sun Microsystems, Trondheim, Norway

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