$sth = $dbh->    prepare("UPDATE $calendar_table
                          SET
                           year = ?,
                           month = ?,
                           day = ?,
                           time_start = ?,
                           time_end = ?,
                           title = ?,
                           location = ?,
                           description = ?,
                           category = ?,
                           posted_by = ?,
                           post_date = ?,
                           b_time = ?,
                           e_time = ?

                          WHERE year = ?
                          AND month = ?
                          AND day = ?
                          AND time_start = ?
                          AND time_end = ?
                          AND title = ?
                          ");