JDBC - Retriving Information

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May 8th, 2008, 01:09 AM

xlordt

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JDBC - Retriving Information

Can anyone please tell me why I keep getting "null" as the result? please.

java Code:

Original - java Code

 
import java.sql.*;
 
class myConnection {
  public static void main (String[] args)
  {
    Statement stmt = null;
    ResultSet rts  = null;
    
    try{
      Class.forName("com.mysql.jdbc.Driver");
      
      Connection conn = DriverManager.getConnection ("jdbc:mysql://localhost:3306/info", "test", "testing");
 
      stmt = conn.createStatement ();
      
      if (stmt.execute ("select * from reps"))
      {
          rts = stmt.getResultSet ();
      }
      
      System.out.println (rts);
      
    }catch (java.lang.ClassNotFoundException e){
       System.err.println (e.getMessage ());
       
    }catch (SQLException ex){
      
       System.out.println (ex.getMessage ());
       System.out.println (ex.getSQLState ());
       
    }finally{
      
       System.out.println ("done");System.out.println (rts);
    }
  }
  
  
}

Last edited by xlordt : May 8th, 2008 at 01:12 AM.

May 8th, 2008, 07:51 AM

crownjewel82

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Your code looks fine. I'd start by checking your database. Or your connection to it.

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May 8th, 2008, 08:22 AM

ishnid

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What's the output of the print statements?

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May 8th, 2008, 08:40 AM

xlordt

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witch one? I get the done one, then I get

> null
>null
>done

Also my database connection is fine, so its pretty weird.

May 8th, 2008, 08:51 AM

ishnid

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You sure there are results in there?

If there are no results, 'execute' will return false, so your result set won't get initialised and so will remain 'null'.

May 8th, 2008, 09:00 AM

xlordt

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Quote:

Originally Posted by ishnid

You sure there are results in there?

If there are no results, 'execute' will return false, so your result set won't get initialised and so will remain 'null'.

You mean in the database? yes there is alot of information in it, let me try this agian.

May 8th, 2008, 09:34 AM

mrider

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It's been a long time since I've used MySQL, so this may or may not be correct. But Java has specific ways to execute queries and updates in addition to "execute". It may be that there's some weird (and seemingly wrong) interaction between your database, your driver, and your program.

Try using:

Code:

rts = stmt.executeQuery ("select * from reps")

instead of:

Code:

#
if (stmt.execute ("select * from reps"))
{
    rts = stmt.getResultSet ();
}

It shouldn't make a difference, but it might. And it's certainly worth a quick test.

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May 8th, 2008, 09:36 AM

xlordt

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Quote:

Originally Posted by mrider

Code:

rts = stmt.executeQuery ("select * from reps")

instead of:

Code:

#
if (stmt.execute ("select * from reps"))
{
    rts = stmt.getResultSet ();
}

It shouldn't make a difference, but it might. And it's certainly worth a quick test.

Ya man I tried that to, is there away to tell if conn actually made a connection?

May 8th, 2008, 10:09 AM

mrider

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