This patch fixes the exception thrown to inform the user the method

getColumnClassName(int) is not implemented. This will futher fixes method
ResultSet.getObject(int) since it requires the getColumnClassName(int) method to return the proper java class used to map the database column.

auther Ed Yu

src/interfaces/jdbc/org/postgresql/jdbc2/ResultSetMetaData.java

@@ -473,8 +473,66 @@ public class ResultSetMetaData implements java.sql.ResultSetMetaData
 	// This can hook into our PG_Object mechanism
 	public String getColumnClassName(int column) throws SQLException
 	{
-		throw org.postgresql.Driver.notImplemented();
-	}
+ /*
+     The following data type mapping came from ../Field.java.
+
+     "int2",
+     "int4","oid",
+     "int8",
+     "cash","money",
+     "numeric",
+     "float4",
+     "float8",
+     "bpchar","char","char2","char4","char8","char16",
+     "varchar","text","name","filename",
+     "bool",
+     "date",
+     "time",
+     "abstime","timestamp"
+
+     Types.SMALLINT,
+     Types.INTEGER,Types.INTEGER,
+     Types.BIGINT,
+     Types.DOUBLE,Types.DOUBLE,
+     Types.NUMERIC,
+     Types.REAL,
+     Types.DOUBLE,
+     Types.CHAR,Types.CHAR,Types.CHAR,Types.CHAR,Types.CHAR,Types.CHAR,
+     Types.VARCHAR,Types.VARCHAR,Types.VARCHAR,Types.VARCHAR,
+     Types.BIT,
+     Types.DATE,
+     Types.TIME,
+     Types.TIMESTAMP,Types.TIMESTAMP
+ */
+
+	int sql_type = getField(column).getSQLType();
+
+     	switch (sql_type)
+        {
+       		case Types.BIT:
+         		return("java.lang.Boolean");
+       		case Types.SMALLINT:
+         		return("java.lang.Integer");
+       		case Types.INTEGER:
+         		return("java.lang.Integer");
+       		case Types.BIGINT:
+         		return("java.lang.Long");
+      		case Types.NUMERIC:
+         		return("java.math.BigDecimal");
+       		case Types.REAL:
+         		return("java.lang.Float");
+       		case Types.DOUBLE:
+         		return("java.lang.Double");
+       		case Types.CHAR:
+       		case Types.VARCHAR:
+         		return("java.lang.String");
+       		case Types.DATE:
+       		case Types.TIME:
+       		case Types.TIMESTAMP:
+         		return("java.sql.Timestamp");
+       		default:
+	 		throw org.postgresql.Driver.notImplemented();
+       }
        
 }