Re: [jira] Updated: (DERBY-795) After calling ResultSet.relative(0) the cursor loses its position

Fri, 10 Feb 2006 03:20:24 -0800 

David W. Van Couvering wrote:
Hi, Andreas. Upon further thought, once we work through the comments on DERBY-934 (still to come) I am going to go ahead and apply all these patches at once, no need for you to do extra work. But a request for next time to please try and keep your patches independent instead of interdependent. 


That is great.
I think the patches are independent, however they are slightly related.

DERBY-918: a patch for improving the test harness


DERBY-934: a set of tests which can be run independentely using 
junit.textui.TestRunner or by using the test harness with patch 918



DERBY-795: a patch for a specific bug in derby. I did not submit extra 
tests for this, since it is covered in 934, however there is a simple 
java program there, which can be run to verify the fix and the bug



There are no compile dependencies between these patches. I think it was 
much better to submit these as independent patches, instead of in one 
huge patch.


Andreas



Thanks!

David

David W. Van Couvering wrote:


Hi, Andreas, your set of patches have a set of dependencies which are 
a little confusing at first, and ultimately somewhat intractable:


DERBY-795 is tested by DERBY-934
DERBY-934 can't be run without, and therefore depends upon, DERBY-918


I really can't just commit one of these patches at a time, it has to 
be all or none.



I really would like each of these patches stand on their own, or at a 
minimum don't submit a dependent patch until the patch it depends upon 
has been committed.


Here's what I would like to see:


DERBY-918 comes with its own sample unit test that verifies that the 
.junit test type works.  Something very simple and easy.



DERBY-795 has its own test that comes with it, rather than being 
tested by DERBY-934



I have some comments on DERBY-934 too, I'll send these in a separate 
email.


Thanks,

David

David W. Van Couvering wrote:


Crud, I missed this comment somehow, I'll look at DERBY-934 again, I 
bet *both* my questions will be answered :)


I'll get back to you if I need anything else, Andreas.

David

Andreas Korneliussen (JIRA) wrote:


     [ http://issues.apache.org/jira/browse/DERBY-795?page=all ]

Andreas Korneliussen updated DERBY-795:
---------------------------------------

    Attachment: DERBY-795.diff
                DERBY-795.diff

Attached is a fix for this issue.

The problem is detected by the jdbcapi/SURQueryMix.junit test 
provided in DERBY-934, when running in embedded mode.




After calling ResultSet.relative(0) the cursor loses its position
-----------------------------------------------------------------

        Key: DERBY-795
        URL: http://issues.apache.org/jira/browse/DERBY-795
    Project: Derby
       Type: Bug
 Components: JDBC
   Versions: 10.1.2.1
Environment: Any
   Reporter: Andreas Korneliussen
   Assignee: Andreas Korneliussen
   Priority: Minor
Attachments: DERBY-795.diff, DERBY-795.diff


After calling rs.relative(0), on a scrollable ResultSet, the cursor 
looses its position, and a rs.getXXX(..) fails with:

SQL Exception: Invalid cursor state - no current row.

Probably caused by the following logic in 
ScrollInsensitiveResultSet.getRelativeRow(int row):

    // Return the current row for 0
        if (row == 0)
        {
                   if ((beforeFirst || afterLast) ||
                       (!beforeFirst && !afterLast)) {
                       return null;
                   } else {
            return getRowFromHashTable(currentPosition);
                   }
        }

The if () will always evaluate to true, regardless of the values of 
beforeFirst and afterLast

Test code:
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
public class RelativeZeroIssue {
          public static void main(String[] args) throws Exception {
              Class.forName("org.apache.derby.jdbc.EmbeddedDriver");

       Connection con = 
DriverManager.getConnection("jdbc:derby:testdb2;create=true");

       con.setAutoCommit(false);

       try {               Statement statement = 
con.createStatement();

                      /** Create the table */
           statement.execute("create table t1(id int)");
           statement.execute("insert into t1 values 1,2,3,4,5,6,7,8");

                      Statement s = 
con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,

                   ResultSet.CONCUR_READ_ONLY);
           ResultSet rs = s.executeQuery("select * from t1");
           rs.next();
           System.out.println(rs.getInt(1));
           System.out.println(rs.relative(0));
           System.out.println(rs.getInt(1));
       }  finally {
                      con.rollback();
           con.close();
       }
   }

 
}

Output from test:
1
false

Exception in thread "main" SQL Exception: Invalid cursor state - no 
current row.
       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.Util.generateCsSQLException(Unknown Source)
       at 
org.apache.derby.impl.jdbc.EmbedConnection.newSQLException(Unknown 
Source)
       at 
org.apache.derby.impl.jdbc.ConnectionChild.newSQLException(Unknown 
Source)
       at 
org.apache.derby.impl.jdbc.EmbedResultSet.checkOnRow(Unknown Source)
       at 
org.apache.derby.impl.jdbc.EmbedResultSet.getColumn(Unknown Source)
       at org.apache.derby.impl.jdbc.EmbedResultSet.getInt(Unknown 
Source)

       at derbytest.RelativeZeroIssue.main(RelativeZeroIssue.java:51)
Java Result: 1






























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