Hi,
I'm looking at using the H2 engine for a persistant java object store
and I ran across a strange problem. I can store and retrieve java
objects no problem in the normal case. However, when I update a row
using an updatable result set, the object in that row is no longer
returned as an object, but rather as an array of bytes.
I'm including below a simple code example which demonstrates the
problem. I store a String as an object in a row, fetch it out again
correctly, then update the row, and fetch again.
The second fetch results in a byte array instead of the correct
object. This happens regardless of the object type.
import java.io.*;
import java.sql.*;
public class UpdateRow {
static int execute(Connection conn, String sql) throws SQLException {
Statement stmt = conn.createStatement();
int rv = stmt.executeUpdate(sql);
stmt.close();
return rv;
}
public static void main(String[] args) throws SQLException,
ClassNotFoundException, IOException {
Class.forName("org.h2.Driver");
File file = File.createTempFile("test", "db");
Connection conn =
DriverManager.getConnection("jdbc:h2:"+file.getAbsolutePath());
execute(conn,"CREATE TABLE object_index (id integer primary key,
object other, number integer)");
PreparedStatement stmt = conn.prepareStatement("INSERT INTO
object_index (id,object) VALUES (1,?)");
stmt.setObject(1,"hello", Types.JAVA_OBJECT);
stmt.execute();
// select object (as string) from row
Statement s = conn.createStatement();
ResultSet rs = s.executeQuery("SELECT object,id,number FROM
object_index WHERE id =1");
if(rs.next()) {
// prints out "hello"
System.out.println(rs.getObject(1));
}
rs.close();
s.close();
// update row
s =
conn.createStatement(ResultSet.TYPE_FORWARD_ONLY,ResultSet.CONCUR_UPDATABLE);
rs = s.executeQuery("SELECT object,id,number FROM object_index
WHERE
id =1");
if(rs.next()) {
// prints out "hello"
System.out.println(rs.getObject(1));
rs.updateInt(2, 1);
rs.updateRow(); // succeeds
}
rs.close();
s.close();
// select again
s = conn.createStatement();
rs = s.executeQuery("SELECT object,id,number FROM object_index
WHERE
id =1");
if(rs.next()) {
// XXX: is no longer a string - is a byte array[] !
System.out.println(rs.getObject(1));
}
rs.close();
s.close();
conn.close();
}
}
-- Joel Carranza
[EMAIL PROTECTED]
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