RE: result set = null (sometimes)

By the way you can save on some code because ResultSet will never be null after 
rs = statement.executeQuery(stm); (it might be empty but not null), so
if (rs.next()) {
        return rs.getString(1).trim();
}
will serve 2 purpose, check if record was found and read it in the same time

-----Original Message-----
From: Mihael Knezevic [mailto:m.knezevic@porta.de]
Sent: Wednesday, January 15, 2003 9:05 AM
To: Java Programming on and around the iSeries / AS400
Subject: RE: result set = null (sometimes)


right. now that you say it ...

i should have seen it myself.

thanx.

-----Original Message-----
From: Alex Pinsky [mailto:apinsky@aeropostale.com] 
Sent: Wednesday, January 15, 2003 2:51 PM
To: Java Programming on and around the iSeries / AS400
Subject: RE: result set = null (sometimes)


Hi Mihael,
As I can see in your first method you forgot to assign
statement.executeQuery(stm) call to a ResultSet object reference. The
code should look like this:

rs = statement.executeQuery(stm);

and then you are ready to process your ResultSet object to retrieve
data. Alex

-----Original Message-----
From: Mihael Knezevic [mailto:m.knezevic@porta.de]
Sent: Wednesday, January 15, 2003 8:32 AM
To: java400-l@midrange.com
Subject: result set = null (sometimes)


hi,

i got a little problem i was pondering about some days now and i still
don't now why it is like that.

i got a class RootAccess through which i would like to get some data
from our DB2/400.

it looks like this:

public class RootAccess
{
        DatabaseMetaData dmd;
        Connection connection;
        ResultSet rs;
        Statement statement;
        String stm;

        public RootAccess()
        {
                try
                {
                        DriverManager.registerDriver(new
AS400JDBCDriver());
                        connection = DriverManager.getConnection
("jdbc:as400://PORTA","user","pwd");
                        dmd = connection.getMetaData();
                        statement = connection.createStatement();
                }
                catch (SQLException sqle)
                { 
                        System.out.println("Problems during database
connection initialization.");
                        System.out.println(sqle.getLocalizedMessage());
                }
        }
                
        public String getCompanyName(int companyID)
        {
                stm = "Select VDDAT from UDVM400DAT.MVDATR where VDSAA =
3 and VDFIR = 10";

                try
                {
                        statement.executeQuery(stm);
                        if(rs != null)
                        {
                                rs.next();
                                return rs.getString(1).trim();
                        }
                        return "";
                }
                catch(SQLException sqle)
                {
                        System.out.println(sqle.getLocalizedMessage());
                        return "";
                }
                finally
                {
                        rs = null;
                }
        }

        public Vector getCompanyNames()
        {
                Vector namesVec = new Vector();
                
                stm = "Select substring(VDDAT,1,20)  from
UDVM400DAT.MVDATR where VDSAA = 3";
                
                try
                {
                        rs = statement.executeQuery(stm);
                        
                        if(rs != null)
                        {
                                while (rs.next())
namesVec.add(rs.getString(1).trim());
                        }               
                }
                catch (SQLException sqle)
                {
                        
                }
                finally
                {
                        rs = null;
                }
                
                return namesVec;
        }
}


my main class looks like this:

public class Test
{
        public static void main(String[] args)
        {
                RootAccess access = new RootAccess();
                
                System.out.println("Firmengruppe 010:" +
access.getCompanyName(10));

                Vector vec = access.getCompanyNames();
                
                for (int i = 0; i < vec.size(); i++)
                {
                        System.out.println("Firmengruppenname:" +
vec.get(i).toString());
                }
        }
}

now my problem:
when i execute the first method, the result set is null. if execute the
same sql statement via several other applications or directly on the
as400 i get the right result (not null). but when i execute the second
method i get the right results. now why does the first sql request
doesn't work. did i forgot something?

os400 v4r5
java (on pc) ibm 1.3.0
jtopen 3.1

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To subscribe, unsubscribe, or change list options,
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Before posting, please take a moment to review the archives
at http://archive.midrange.com/java400-l.


_______________________________________________
This is the Java Programming on and around the iSeries / AS400 (JAVA400-L) 
mailing list
To post a message email: JAVA400-L@midrange.com
To subscribe, unsubscribe, or change list options,
visit: http://lists.midrange.com/mailman/listinfo.cgi/java400-l
or email: JAVA400-L-request@midrange.com
Before posting, please take a moment to review the archives
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