This section describes how to set ResultSet to be scrollable and how to move cursor backward.
There are two options when setting ResultSet to be scrollable:
TYPE_SCROLL_INSENSITIVE -
The result set is scrollable. Its cursor can move forward or backward and can be moved to a particular row or to a row whose position is relative to its current position.
The result set generally does not show changes to the underlying database that are made while it is open. The membership, order, and column values of rows are typically fixed when the result set is created.
TYPE_SCROLL_SENSITIVE -
The result set is scrollable. Its cursor can move forward or backward and can be moved to a particular row or to a row whose position is relative to its current position.
The result set is sensitive to changes made while it is open. If the underlying column values are modified, the new values are visible, thus providing a dynamic view of the underlying data. The membership and ordering of rows in the result set may be fixed or not, depending on the implementation.
Generally, TYPE_SCROLL_INSENSITIVE is the preferred option. The data contained in the ResultSet object is fixed (a snapshot) when the object is created.
Here is a sample program that shows you how to create a scrollable ResultSet and how to move the cursor backward:
/**
* DerbyScrollableResultSet.java
* Copyright (c) 2007 by Dr. Herong Yang. All rights reserved.
*/
import java.sql.*;
public class DerbyScrollableResultSet {
public static void main(String [] args) {
Connection con = null;
try {
con = DriverManager.getConnection(
"jdbc:derby://localhost/TestDB");
// Create a Statement for scrollable ResultSet
Statement sta = con.createStatement(
ResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_READ_ONLY);
// Catch the ResultSet object
ResultSet res = sta.executeQuery("SELECT * FROM Profile");
// Check ResultSet's scrollability
if (res.getType() == ResultSet.TYPE_FORWARD_ONLY) {
System.out.println("ResultSet non-scrollable.");
} else {
System.out.println("ResultSet scrollable.");
}
System.out.println("List of Profiles:");
// Move the cursor to the last row
res.last();
// Stop the loop when the cursor is positioned before the first row
while (!res.isBeforeFirst()) {
String firstName = res.getString("FirstName");
String lastName = res.getString("LastName");
System.out.println(" "+firstName+" "+lastName);
// Move the cursor backward one row
res.previous();
}
// Close ResultSet and Statement
res.close();
sta.close();
con.close();
} catch (Exception e) {
System.err.println("Exception: "+e.getMessage());
}
}
}
The output matches my expectation: profiles are listed backward.
ResultSet scrollable.
List of Profiles:
Keith Harris
19c2 8770b
1090 3fb07
13ba 88356
1352 17d9
11bd 58ad0
1002 e3873
21d6 efd17
Janet Gates
