秒杀都是先保存后更新，保存成功，但是更新不一定会成功
dynamicQuery.save(killed);
nativeSql = "UPDATE seckill SET number=number-1 WHERE seckill_id=? AND number>0";
dynamicQuery.nativeExecuteUpdate(nativeSql, new Object[]{seckillId});

如果更新语句执行完成就不会超卖了 redis分布式锁情况下
nativeSql = "UPDATE seckill SET number=number-1 WHERE seckill_id=? AND number>0";
int i = dynamicQuery.nativeExecuteUpdate(nativeSql, new Object[]{seckillId});
if (i > 0) {
SuccessKilled killed = new SuccessKilled();
killed.setSeckillId(seckillId);
killed.setUserId(userId);
killed.setState((short)0);
killed.setCreateTime(new Timestamp(new Date().getTime()));
dynamicQuery.save(killed);
}