Unable to delete

[subhashchandra medhiassam]

hi all,
I have a table named Contact in mysql running on localhost. The columns in the table are ID,FIRSTNAME, LASTNAME and EMAIL.
There's only one row in the table. The values in the row are ID = 6, FIRSTNAME = Subhash, LASTNAME = Medhi and EMAIL = [e-mail] .

I am using the following code to delete this row:

package roseindia.tutorial.hibernate;
 
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
/**
 * 
 * @author esubmed
 *
 */
public class DeleteHQLExample {
  /**
   * 
   * @param args
   */
  public static void main(String[] args) {
    // TODO Auto-generated method stub  
    Session session = null;
    try {
      SessionFactory fact = new Configuration().configure().buildSessionFactory();
      session = fact.openSession();
      
      String hql = "delete from Contact contact where id = 6";
      Query query = session.createQuery(hql);
      int row = 0;
      row = query.executeUpate();
      
      if (row == 0){
        System.out.println("Couldn't delete any row!");
      }
      else{
        System.out.println("Deleted Row: " + row);
      }
      session.close();
    }
    catch(Exception e){
      System.out.println(e.getMessage());
    }
  }
} 

if i execute this code, the row doesn't get deleted and i get the following output:

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
null


if use try-catch statement around "row = query.executeUpate();" in the following way:

 
package roseindia.tutorial.hibernate;
 
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
/**
 * 
 * @author esubmed
 *
 */
public class DeleteHQLExample {
  /**
   * 
   * @param args
   */
  public static void main(String[] args) {
    // TODO Auto-generated method stub  
    Session session = null;
    try {
      SessionFactory fact = new Configuration().configure().buildSessionFactory();
      session = fact.openSession();
      //long id = 6;
      //Object contact = session.load(Contact.class, id);
      //session.delete(contact);
      String hql = "delete from Contact contact where id = 6";
      Query query = session.createQuery(hql);
      int row = 0;
      try{
  row = query.executeUpate();
      }catch(NullPointerException ne){
  System.out.println(ne.getMessage());
      }
      
      if (row == 0){
        System.out.println("Couldn't delete any row!");
      }
      else{
        System.out.println("Deleted Row: " + row);
      }
      session.close();
    }
    catch(Exception e){
      System.out.println(e.getMessage());
    }
  }
} 

the row doesn't get deleted, and i get the following output:

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
null
Couldn't delete any row!

Kindly do let me know where i might have gone wrong.

[ Edited to use code tags - Paul Sturrock ]
[ September 11, 2008: Message edited by: Paul Sturrock ]

[Paul Sturrock]

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
null

This output is log4j telling you you have not configured your loggers correctly. Nothing to do with Hibenrtae itself. I'd double check what you've got in log4j.properties and where it is.

Your code is assuming Hibernate is working "non-transationally" i.e. there either are no transactions involved, or if there are they are auto-commiting. Auto-commit is disabled by default in Hibernate, so unless you have configured it otherwise you'll need to wrap your operation in a transaction and commit it at the end. See this.
[ September 11, 2008: Message edited by: Paul Sturrock ]

[arulk pillai]

  Session sess = factory.openSession();
 Transaction tx;
 try {
     tx = sess.beginTransaction();
     //do some work
     ...
     tx.commit();
 }
 catch (Exception e) {
     if (tx!=null) tx.rollback();
     throw e;
 }
 finally {
     sess.close();
 }
   

[Cameron Wallace McKenzie]

Throw this in your log4j.properties file, and you should get rid of the warnings:

http://ideoplex.com/id/386/controlling-hibernate-output-with-log4j

  ### direct log messages to stdout ### 
log4j.appender.stdout=org.apache.log4j.ConsoleAppender 
log4j.appender.stdout.Target=System.out 
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout 
log4j.appender.stdout.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n 
 
### direct messages to file hibernate.log ### 
log4j.appender.file=org.apache.log4j.FileAppender 
log4j.appender.file.File=hibernate.log 
log4j.appender.file.layout=org.apache.log4j.PatternLayout 
log4j.appender.file.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n 
 
### set log levels - for more verbose logging change 'info' to 'debug' ## 
 
log4j.rootLogger=warn, file 
 
log4j.logger.net.sf.hibernate=info 
 
### enable the following line if you want to track down connection ### 
### leakages when using DriverManagerConnectionProvider ### 
#log4j.logger.net.sf.hibernate.connection.DriverManagerConnectionProvider=trace 
 
### log JDBC bind parameters ### 
log4j.logger.net.sf.hibernate.type=info 
 
### log prepared statement cache activity ### 
log4j.logger.net.sf.hibernate.ps.PreparedStatementCache=info 

-Cameron McKenzie
[ September 11, 2008: Message edited by: Cameron Wallace McKenzie ]