在MySQL中查找下一个可用的ID [英] Finding the next available id in MySQL

问题描述

我必须在MySQL数据库中找到下一个可用的id(如果数据库中有5个数据，我必须获得下一个可用的插入位置6).我怎样才能做到这一点? 我曾经使用过MAX(id)，但是当我从数据库中删除一些行时，它仍然保留了没有更新的旧最大值.

I have to find the next available id (if there are 5 data in database, I have to get the next available insert place which is 6) in a MySQL database. How can I do that? I have used MAX(id), but when I delete some rows from the database, it still holds the old max value it didn't update.

推荐答案

我认为您无法确定 next id，因为有人可能会在您询问后插入新行为下一个ID.您至少需要一笔交易，并且如果我没记错的话，您只能在插入之后获得使用的实际ID，至少这是处理该ID的常用方法-请参见 http://dev.mysql.com/doc/refman/5.0/zh/getting-unique-id.html

I don't think you can ever be sure on the next id, because someone might insert a new row just after you asked for the next id. You would at least need a transaction, and if I'm not mistaken you can only get the actual id used after inserting it, at least that is the common way of handling it -- see http://dev.mysql.com/doc/refman/5.0/en/getting-unique-id.html

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