private PreparedStatement buildUpdateStatement(Connection conn_loc, String tableName,
            List colDescriptors, String whereField)
            throws SQLException {
        StringBuffer sql = new StringBuffer("UPDATE ");
        (sql.append(tableName)).append(" SET ");
        final Iterator i = colDescriptors.iterator();
        while (i.hasNext()) {
            (sql.append((String) i.next())).append(" = ?, ");
        }
        sql = new StringBuffer((sql.toString()).substring(0, (sql.toString()).lastIndexOf(", ")));
        ((sql.append(" WHERE ")).append(whereField)).append(" = ?");
        final String finalSQL = sql.toString();
        return conn_loc.prepareStatement(finalSQL);
    }