Chris,
It is also important to consider that it is possible for the number of rows
that will be returned to change between the two queries if other sessions
are updating the data base. It would be entirely possible for the select
count(*) to return a count of 1000 and have the second query return zero
rows.
Regards,
Bob
------------------------------------------------------------------------
-------------------
Bob Withers Two things are infinite: the
universe and
[EMAIL PROTECTED] human stupidity, and I'm not sure
about
http://www.pobox.com/~bwit the universe. - Albert Einstein
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On Tuesday, June 29, 1999 11:35 AM, Chris Pratt
[SMTP:[EMAIL PROTECTED]] wrote:
> >From what I understand, the first query is only slightly faster than the
> second (since it doesn't have to build a full ResultSet), but Oracle has
> pretty aggressive caching, so the second query (having the same where
> clause) should run out of the cached data from the first call and be very
> quick. Overall, it's slower, but nowhere near twice as slow.
> (*Chris*)
>
> ----- Original Message -----
> From: Xizhen Wang <[EMAIL PROTECTED]>
> To: Chris Pratt <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
> Cc: <[EMAIL PROTECTED]>
> Sent: Monday, June 28, 1999 6:34 PM
> Subject: Re: Number of rows a query retrieved?
>
>
> >
> >
> > Chris Pratt wrote:
> > >
> > > Oh, I should have mentioned, that using simple SQL, you can also use
the
> > > COUNT operator to test how many rows will be returned. Like this:
> > >
> > > select count(*) from employees where city='San Jose'
> > > select * from employees where city='San Jose'
> >
> > Thank you!
> > So another question is: is the first query as time-comsuming as the 2nd
> > one?
> > if this is true, i'd rather do only one query.
> >
> > thanks!
> >
> > xizhen
> >
> >
> > >
> > > The first query will return a single row in its ResultSet that
consists
> of
> > > one Numeric value equal to the number of rows that the second query
will
> > > return (Assuming that no updates happen between the two invocations).
> > > (*Chris*)
> > >
> > > ----- Original Message -----
> > > From: Chris Pratt <[EMAIL PROTECTED]>
> > > To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
> > > Sent: Monday, June 28, 1999 2:42 PM
> > > Subject: Re: Number of rows a query retrieved?
> > >
> > > > In standard JDBC, there is no way to tell this before you have read
> the
> > > last
> > > > row. There are packages, like Village or Town, that do have this
> > > > capability, but I have not tested them. You could also use a true
> OODB,
> > > > like CloudScape, which has this type of capability.
> > > > (*Chris*)
> > > >
> > > > ----- Original Message -----
> > > > From: Xizhen Wang <[EMAIL PROTECTED]>
> > > > To: <[EMAIL PROTECTED]>
> > > > Sent: Monday, June 28, 1999 12:44 AM
> > > > Subject: Number of rows a query retrieved?
> > > >
> > > >
> > > > > Hi! In jdbc, how to know the number of rows a query retrieved? Is
> there
> > > > > a good way other than using ResultSet.next()?
> > > > >
> > > > > Thanks!
> > > > >
> > > > >
> > > >
> > >
>
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> > > > >
> > > >
> >
>
>
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