[DERBY-186] isFirst() returns true when relative(x) goes beyond result set

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 10.0.2.0
• Fix Version/s: 10.1.1.0
• Component/s: JDBC
• Environment: Windows XP SP1 Professional
• Assignee: Unassigned
• Reporter: George Baklarz
• Created: 29/Mar/05 13:21
• Updated: 06/Apr/05 10:08
• Resolved: 06/Apr/05 10:08

Description

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?