关于MySQL并发查询的问题
比如有一个逻辑，判断一个活动总支付人数，每满1000人就随机送礼包，查询支付总人数：
<code>select count(*) as total from payrecord where act_id='act'</code>
因为没有redis，其实我很想用redis计数，但是没有，假如同时5个人支付，假设第999人，和第1000，第1001人同时支付的，这个时候会不会都是返回1001的情况，这样就没有触发发礼品的逻辑。
对这种并发查询一个结果，特别是数量的情况，假设没有redis，还有什么办法可以保证可靠性？
回复内容：
比如有一个逻辑，判断一个活动总支付人数，每满1000人就随机送礼包，查询支付总人数：
<code>select count(*) as total from payrecord where act_id='act'</code>
因为没有redis，其实我很想用redis计数，但是没有，假如同时5个人支付，假设第999人，和第1000，第1001人同时支付的，这个时候会不会都是返回1001的情况，这样就没有触发发礼品的逻辑。
对这种并发查询一个结果，特别是数量的情况，假设没有redis，还有什么办法可以保证可靠性？
可以存一个锁（锁存在哪里并不重要），在第1000人的时候上锁，逻辑上先判断是否已经被锁，再去count.
简单的方法是每在随机送礼包前判断是否有发送记录，有的话，则跳过去（这一块的并发应该不受影响），方法和楼上的差不多。
加上where不就行了吗？
<code>protected function _afterPayment($order) {
select count(*) from order where status = 'paid' and paid_time addOrderItem($order.id, $礼包_id);
}
}</code>
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