Help coderanch get a
new server
by contributing to the fundraiser
  • Post Reply Bookmark Topic Watch Topic
  • New Topic
programming forums Java Mobile Certification Databases Caching Books Engineering Micro Controllers OS Languages Paradigms IDEs Build Tools Frameworks Application Servers Open Source This Site Careers Other Pie Elite all forums
this forum made possible by our volunteer staff, including ...
Marshals:
  • Campbell Ritchie
  • Jeanne Boyarsky
  • Ron McLeod
  • Paul Clapham
  • Liutauras Vilda
Sheriffs:
  • paul wheaton
  • Rob Spoor
  • Devaka Cooray
Saloon Keepers:
  • Stephan van Hulst
  • Tim Holloway
  • Carey Brown
  • Frits Walraven
  • Tim Moores
Bartenders:
  • Mikalai Zaikin

How to determine the number of Result set records.

 
Ranch Hand
Posts: 36
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
I am using MySql if that matters in answering my question.
I have written my first program using MySql and can display information from an SQL query.
Question: What is the best way to determine the number of records returned by the result set.
.
.
ResultSet RS = Stmt.executeQuery(theSQLQuery);
while (RS.next()) {
System.out.println(RS.getString(1));
}
I know I can put my own "counter" in the while loop. Is there something like RS.size(). I looked in the online Java docs I have and did not see anything that was apparent.
Thanks.
 
Greenhorn
Posts: 23
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Although there is no direct method to find the no. of rows, it's possible by using Scrollable Resultset (supported in JDBC2).
I don't know if it works with MySql though. Here is some code I tried with oracle.


[This message has been edited by sanjay yermalkar (edited November 02, 2001).]
[This message has been edited by sanjay yermalkar (edited November 02, 2001).]
 
Ranch Hand
Posts: 1879
MySQL Database Suse
  • Mark post as helpful
  • send pies
    Number of slices to send:
    Optional 'thank-you' note:
  • Quote
  • Report post to moderator
Although sanjay's procedure will give you the count you need, it probably isn't as effecient as you may think:
1. It uses a scrollable resultset which by design are slower than non-scrollable
2. From what I've read, the getLast() method just loops through the recordset to the last record anyways...and then rs.first()/rs.beforeFirst() loops back to the beginning.
In my experience I have found that using the "select count(*) from emp where..." before I execute "select empno, name...from emp where..." is more efficient especially for larger resultsets.

I did some testing using both methods and my results were:
- Using "select count (*)" as described above - 200 to 300 milliseconds to execute in 10 trials
- Using the getRow() technique as described by sanjay - 500 to 600 milliseconds to execute in 10 trials
I just thought I would test this because I have never seen test results comparing the 2 techniques. Anyways, you can run your own tests if you like,

Jamie
 
Nothing up my sleeve ... and ... presto! A tiny ad:
We need your help - Coderanch server fundraiser
https://coderanch.com/t/782867/Coderanch-server-fundraiser
reply
    Bookmark Topic Watch Topic
  • New Topic