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From Anand Bashyam Narasimhan <ana...@digitalthink.com>
Subject RE: ResultSet
Date Wed, 29 May 2002 11:42:56 GMT
Manuel,

For you to be able to invoke the clone() method on an Object does'nt it have
to implement Cloneable interface. That's the reason why to are getting a
compile time error. 

If JDK is not a constraint you can switch to 1.2 or 1.3.x and use
CachedRowSet which allow you to have bidirectional. Another programmatic
approach would be when you are iterating through the rows to count the rows
push all the data in each row into a data model that mimics each row in the
table and keep adding them in an Array of some sort.

Of course if you don't want to do this...then solution to do "select
count(*)..." would be the option I would go with.

Anand

-----Original Message-----
From: Manuel Rodriguez Diaz [mailto:mrodr@ts.es]
Sent: Wednesday, May 29, 2002 1:00 PM
To: Tomcat Developers List
Subject: Re: ResultSet


Thankyou.
I've just tried this.
In fact i write a select count(1) which is faster (for a reason i don't
know).
The problem is that in many cases i have a group clause that cause problems
with
this method.
So i thought this:

resultset= statement.CreateQuery();
resultset2= resultset;

Obviously, both resultset and resultset2 points the same set of data.
Because i have java 1.1, my resultsets are forward-only. When i loop
resultset
to count, resultset2 loops too.

I've tried to clone the resultset too.
    ResultSet temp;
    Object aux= new Object();
    aux= (java.lang.Object)rs;
    temp= (ResultSet)aux.clone();

But it fails at compilation time. What can i do?

James Mitchell escribió:

> have you tried getting the row count from the db instead of looping
> yourself?
>
> this approach will offload a few resources (counting) back to the db
> (assuming its tiered) where it belongs(IMHO)
>
> //assuming your db supports count() [duh]
> //if you build your sql in chunks
> String sqlSelect = "Select Col1, Col2 "
> String sqlFrom   = "From myTable "
> String sqlWhere  = "Where Col3 = 'SomeVal'";
>
> //typically a helper function
> //execute the sql on your connection
> Resultset rs = getMyResults("Select count(*) as ct " + sqlFrom +
sqlWhere);
> size = rs.getLong("ct")
> //proceed as you did before, but this time you have the row count.
>
> Hope this helps.
>
> James Mitchell
>
> > -----Original Message-----
> > From: Manuel Rodriguez Diaz [mailto:mrodr@ts.es]
> > Sent: Tuesday, May 28, 2002 12:56 PM
> > To: tomcat-dev@jakarta.apache.org
> > Subject: ResultSet
> >
> >
> >
> > Hi all,
> > I'm working with java 1.1. (this is a mandatory requirement).
> > In this version of Java, resultset are "FORWARD ONLY".
> > The fact is that i need to count the rows contained in a resultset
> > before displaying its data and the  way i've thought to do this is read
> > all the resultset.
> > rows= 0;
> > while( rs.next()) {
> >     rows++;
> > }
> >
> > With my actual version of java, I would need to re-execute the query
> > again to get the pointer "beforeFirsted".
> > Is there any way to obtain a independent copy of a ResultSet without
> > executing the query again?
> >
> > Thankyou
> >
> >
> > --
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