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Date: Tue, 29 Mar 2005 16:52:05 +0530
From: Shreyas Kaushik <Shreyas.Kaushik@Sun.COM>
Subject: Re: [jira] Commented: (DERBY-186) isFirst() returns true when
 relative(x) goes beyond result set
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Please find the patch for this attached. I have added a test case for 
this as well.
I ran the derbyall test suite without any failures.

~ Shreyas

Shreyas Kaushik (JIRA) wrote:

>     [ http://issues.apache.org/jira/browse/DERBY-186?page=comments#action_61704 ]
>     
>Shreyas Kaushik commented on DERBY-186:
>---------------------------------------
>
>I guess the problem is not whether you make a call to isFirst() first or next. The way a call to relative() is behaving when the param passed to it is more than the number of rows, is what is causing the problem. 
>
>I have small fix going for this which I am still testing. Will update when I get some results.
>
>~ Shreyas
>
>  
>
>>isFirst() returns true when relative(x) goes beyond result set
>>--------------------------------------------------------------
>>
>>         Key: DERBY-186
>>         URL: http://issues.apache.org/jira/browse/DERBY-186
>>     Project: Derby
>>        Type: Bug
>>  Components: JDBC
>>    Versions: 10.0.2.0
>> Environment: Windows XP SP1 Professional
>>    Reporter: George Baklarz
>>    
>>
>
>  
>
>>Bizarre error. Not sure if this is a JDBC, Derby, or Java issue.
>>An opened result set has 4 records. A call to relative(3) while on row 3 should result in isAfterLast=true, and isFirst, isBeforeFirst, and IsLast set to false. However, the result is isAfterLast=True and isFirst=True.
>>ij 
>>connect 'IsAfter;create=true';
>>create table x (a char(1)); 
>>insert into x values '1','2','3','4';
>>quit;
>>import java.sql.*; 
>>public class ErrIsFirst {
>>  public static void main(String argv[]) throws SQLException {
>>    Connection conn = null;
>>    Statement s = null;
>>    ResultSet rs = null;
>>    String DerbyDriver = "org.apache.derby.jdbc.EmbeddedDriver";
>>    String returnValue;
>>      
>>    try {
>>       Class.forName(DerbyDriver).newInstance();
>>    }
>>    catch (Exception NoDriver) {
>>       System.out.println("Derby driver not found: " + DerbyDriver);
>>       NoDriver.printStackTrace();
>>       System.exit(1);
>>    }
>>    try {
>>      conn = DriverManager.getConnection("jdbc:derby:IsAfter"); 
>>      s = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY); 
>>      rs = s.executeQuery( "SELECT A FROM X");
>>      rs.next(); // First Record
>>      returnValue = rs.getString("A");     
>>      System.out.println("Value="+returnValue); 
>>      
>>      rs.relative(2);
>>      System.out.println("isFirst=" + rs.isFirst() + " isLast=" + rs.isLast() + " isAfterLast=" + rs.isAfterLast());
>>      returnValue = rs.getString("A");     
>>      System.out.println("Value="+returnValue); 
>>      rs.relative(-2);
>>      returnValue = rs.getString("A");     
>>      System.out.println("Value="+returnValue);
>>      rs.relative(10);
>>      System.out.println("isFirst=" + rs.isFirst() + " isLast=" + rs.isLast() + " isAfterLast=" + rs.isAfterLast());
>>      returnValue = rs.getString("A");     
>>      System.out.println("Value="+returnValue); 
>>      rs.close(); 
>>      s.close();
>>    }
>>    catch (SQLException se) {
>>      String SQLState = se.getSQLState(); 
>>      String SQLMessage = se.getMessage();
>>      System.out.println("Error = "+SQLState);
>>      System.out.println(SQLMessage);
>>    }
>>  }
>>}
>>The results on my system are:
>>Value=1
>>isFirst=false isLast=false isAfterLast=false
>>Value=3
>>Value=1
>>isFirst=true isLast=false isAfterLast=true
>>Error = 24000
>>Invalid cursor state - no current row.
>>If you eliminate the first println call to isFirst() you get the following (correct) results.
>>Value=1
>>Value=3
>>Value=1
>>isFirst=false isLast=false isAfterLast=true
>>Error = 24000
>>Invalid cursor state - no current row.
>>Okay, so where did we go wrong?
>>    
>>
>
>  
>

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Index: java/engine/org/apache/derby/impl/sql/execute/ScrollInsensitiveResultSet.java
===================================================================
--- java/engine/org/apache/derby/impl/sql/execute/ScrollInsensitiveResultSet.java	(revision 159352)
+++ java/engine/org/apache/derby/impl/sql/execute/ScrollInsensitiveResultSet.java	(working copy)
@@ -750,6 +750,7 @@
 			else
 			{
 				afterLast = true;
+                currentPosition = positionInSource + 1;
 			}
 		}
 
Index: java/testing/org/apache/derbyTesting/functionTests/tests/jdbcapi/testRelative.java
===================================================================
--- java/testing/org/apache/derbyTesting/functionTests/tests/jdbcapi/testRelative.java	(revision 0)
+++ java/testing/org/apache/derbyTesting/functionTests/tests/jdbcapi/testRelative.java	(revision 0)
@@ -0,0 +1,98 @@
+package org.apache.derbyTesting.functionTests.tests.jdbcapi;
+
+
+import java.sql.*;
+
+import org.apache.derby.tools.ij;
+import org.apache.derby.tools.JDBCDisplayUtil;
+
+public class testRelative {
+   public static void main(String[] args) {
+        test1(args);        
+    }
+    
+    public static void test1(String []args) {   
+                Connection con;
+                ResultSet rs;
+                PreparedStatement stmt = null;
+                PreparedStatement pStmt = null;
+                Statement stmt1 = null;
+                String returnValue = null;
+
+                System.out.println("Test testRelative starting");
+
+                try
+                {
+                        // use the ij utility to read the property file and
+                        // make the initial connection.
+                        ij.getPropertyArg(args);
+                        con = ij.startJBMS();
+					
+			con.setAutoCommit(false);                        			              
+                        
+                        stmt = con.prepareStatement("create table testRelative(name varchar(10), i int)");
+   			stmt.executeUpdate();
+   			con.commit();
+   			
+   			pStmt = con.prepareStatement("insert into testRelative values (?,?)");
+   			   			
+   			pStmt.setString(1,"work1");
+			pStmt.setNull(2,1);
+			pStmt.addBatch();
+			
+			pStmt.setString(1,"work2");
+			pStmt.setNull(2,2);
+			pStmt.addBatch();
+			
+			pStmt.setString(1,"work3");
+			pStmt.setNull(2,3);
+			pStmt.addBatch();
+			
+			pStmt.setString(1,"work4");
+			pStmt.setNull(2,4);
+			pStmt.addBatch();
+
+		
+			pStmt.executeBatch();
+			con.commit();
+
+			stmt1 = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,ResultSet.CONCUR_READ_ONLY);
+		        rs = stmt1.executeQuery("select * from testRelative");						
+
+   			rs.next(); // First Record
+   			returnValue = rs.getString("name");
+   			System.out.println("Value="+returnValue);
+
+   			rs.relative(2);
+   			System.out.println("isFirst=" + rs.isFirst() + " isLast=" + rs.isLast() + " isAfterLast=" + rs.isAfterLast());
+   			returnValue = rs.getString("name");
+   			System.out.println("Value="+returnValue);
+
+   			rs.relative(-2);
+   			returnValue = rs.getString("name");
+   			System.out.println("Value="+returnValue);
+
+   			rs.relative(10);
+   			System.out.println("isFirst=" + rs.isFirst() + " isLast=" + rs.isLast() + " isAfterLast=" + rs.isAfterLast());
+
+   			returnValue = rs.getString("name");
+   			System.out.println("Value="+returnValue);
+
+ 		} catch(SQLException sqle) {
+ 		   dumpSQLExceptions(sqle);
+ 		   sqle.printStackTrace();
+ 		} catch(Throwable e) {
+ 		   System.out.println("FAIL -- unexpected exception: "+e);
+                   e.printStackTrace();
+
+ 		}
+      }
+      
+      static private void dumpSQLExceptions (SQLException se) {
+                System.out.println("FAIL -- unexpected exception");
+                while (se != null) {
+                        System.out.println("SQLSTATE("+se.getSQLState()+"): "+se);
+                        se = se.getNextException();
+                }
+        }
+}
\ No newline at end of file
Index: java/testing/org/apache/derbyTesting/functionTests/master/testRelative.out
===================================================================
--- java/testing/org/apache/derbyTesting/functionTests/master/testRelative.out	(revision 0)
+++ java/testing/org/apache/derbyTesting/functionTests/master/testRelative.out	(revision 0)
@@ -0,0 +1,9 @@
+Test testRelative starting
+Value=work1
+isFirst=false isLast=false isAfterLast=false
+Value=work3
+Value=work1
+isFirst=false isLast=false isAfterLast=true
+FAIL -- unexpected exception
+SQLSTATE(24000): SQL Exception: Invalid cursor state - no current row.
+SQL Exception: Invalid cursor state - no current row.

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