db-derby-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Pavel Bortnovskiy <PBortnovs...@Jefferies.com>
Subject Resetting ResultSet with first() or beforeFirst()
Date Wed, 09 Jun 2010 17:32:49 GMT
Hi:

I am trying to reset a given ResultSet back to the first record, so that I 
could iterate through its records one more time, after it's already been 
done once. So, my code does something like this (it's pseudo-code, and in 
the real application these two passes are done in different parts of the 
application):

// get ResultSet
final ResultSet resultSet = ((PreparedStatement) 
m_statement).executeQuery();
final int columnCount = resultSet.getMetaData().getColumnCount();
// First Pass through the data
while (resultSet.next()) {
        for (int i = 1; i <= columnCount; i++) {
                if (resultSet.wasNull()) {
                        doSomethingWithNULL();
                } else {
                        doSomethingWithObject(resultSet.getObject(i));
                }
        }
}
// Reset ResultSet - but it generates SQLException: The 'beforeFirst()' 
method is only allowed on scroll cursors
resultSet.beforeFirst();
// Second Pass through the data
while (resultSet.next()) {
        for (int i = 1; i <= columnCount; i++) {
                if (resultSet.wasNull()) {
                        doSomethingElseWithNULL();
                } else {
                        doSomethingElseWithObject(resultSet.getObject(i));
                }
        }
}


However, resultSet.beforeFirst() generates an exception:

java.sql.SQLException: The 'beforeFirst()' method is only allowed on 
scroll cursors.
        at 
org.apache.derby.impl.jdbc.SQLExceptionFactory40.getSQLException(Unknown 
Source)
        at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Unknown 
Source)
        at org.apache.derby.impl.jdbc.Util.newEmbedSQLException(Unknown 
Source)
        at 
org.apache.derby.impl.jdbc.EmbedResultSet.checkScrollCursor(Unknown 
Source)
        at org.apache.derby.impl.jdbc.EmbedResultSet.beforeFirst(Unknown 
Source)
Caused by: java.sql.SQLException: The 'beforeFirst()' method is only 
allowed on scroll cursors.
        at 
org.apache.derby.impl.jdbc.SQLExceptionFactory.getSQLException(Unknown 
Source)
        at 
org.apache.derby.impl.jdbc.SQLExceptionFactory40.wrapArgsForTransportAcrossDRDA(Unknown 
Source)
        ... 8 more

Could someone please help me out to understand what may be done 
incorrectly and what would be the right approach to enable two-pass logic 
through the RecordSet?

Thanks,

Pavel.




Jefferies archives and monitors outgoing and incoming e-mail. The contents of this email,
including any attachments, are confidential to the ordinary user of the email address to which
it was addressed. If you are not the addressee of this email you may not copy, forward, disclose
or otherwise use it or any part of it in any form whatsoever. This email may be produced at
the request of regulators or in connection with civil litigation. Jefferies accepts no liability
for any errors or omissions arising as a result of transmission. Use by other than intended
recipients is prohibited.  In the United Kingdom, Jefferies operates as Jefferies International
Limited; registered in England: no. 1978621; registered office: Vintners Place, 68 Upper Thames
Street, London EC4V 3BJ.  Jefferies International Limited is authorised and regulated by the
Financial Services Authority.
Mime
View raw message