Re: ResultSet

2002-05-29 Thread Manuel Rodriguez Diaz 

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:[EMAIL PROTECTED]]
  Sent: Tuesday, May 28, 2002 12:56 PM
  To: [EMAIL PROTECTED]
  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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RE: ResultSet

2002-05-29 Thread Anand Bashyam Narasimhan 

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:[EMAIL PROTECTED]]
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:[EMAIL PROTECTED]]
  Sent: Tuesday, May 28, 2002 12:56 PM
  To: [EMAIL PROTECTED]
  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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RE: ResultSet

2002-05-28 Thread James Mitchell 

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:[EMAIL PROTECTED]]
 Sent: Tuesday, May 28, 2002 12:56 PM
 To: [EMAIL PROTECTED]
 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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RE: ResultSet

2002-03-11 Thread Ed Yu 

Try to do this:

if ((res.getString(3) != null)  (res.getString(3).length  0))
{
...
}

It is because java.util.String must use its equals() method for string
comparison. The only logical operator you can use is for null
comparison.

Also some database distinguish between empty string '' and null value,
just becareful of that!

 -Original Message-
 From: Paul Wallace [SMTP:[EMAIL PROTECTED]]
 Sent: Monday, March 11, 2002 3:58 AM
 To:   Tomcat Developers List
 Subject:  ResultSet
 
 Hi,
 For the brave, can anyone guess why with this rather unsociable
 code:
 
 
   if ((res.getString(3) == null) || (res.getString(3) == )) {
out.println(tda href=takeDetails.jsp?timeSlot= +
 res.getString(2) + myDate= + myDate +  + res.getString(2) +
 /a/td);
}
   if ((res.getString(3) != null) || (res.getString(3) != )) {
out.println(td + res.getString(3)+   + res.getString(2) +
 /td);
}
 
 
 the first condition is NEVER satisfied, even though out.println of
 res.getString(3) does not display anything! Ie res.getString(3) IS
 null,
 empty or whatever, but the condition is never satisifed. Quickly
 again, this
 is executed:
 
 
   if ((res.getString(3) != null) || (res.getString(3) != )) {
out.println(td + res.getString(3)+   + res.getString(2) +
 /td);
}
 
 
 even though - out.println(td + res.getString(3)+   -  shows it
 is
 empty (no output)!
 
 Thanks
 
 Paul.
 
 
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Re: ResultSet

2002-03-11 Thread Micael Padraig Og mac Grene 

If you want to compare String objects as literals, use the intern() method.

Micael

At 03:58 PM 3/11/02 +0700, you wrote:
Hi,
 For the brave, can anyone guess why with this rather unsociable code:


   if ((res.getString(3) == null) || (res.getString(3) == )) {
out.println(tda href=takeDetails.jsp?timeSlot= +
res.getString(2) + myDate= + myDate +  + res.getString(2) +
/a/td);
}
   if ((res.getString(3) != null) || (res.getString(3) != )) {
out.println(td + res.getString(3)+   + res.getString(2) +
/td);
}


the first condition is NEVER satisfied, even though out.println of
res.getString(3) does not display anything! Ie res.getString(3) IS null,
empty or whatever, but the condition is never satisifed. Quickly again, this
is executed:


   if ((res.getString(3) != null) || (res.getString(3) != )) {
out.println(td + res.getString(3)+   + res.getString(2) +
/td);
}


even though - out.println(td + res.getString(3)+   -  shows it is
empty (no output)!

Thanks

Paul.


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