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mysql 表id 自增长，sql语句(插入)不对，插入失败 id 怎么还占位？

比如说，第一次插入成功为id 1，第二次失败，下一次再插入 id 就是3 了。第二次失败怎么导致了id 的跨越？以前没发现这种情况，是pdo 特有的吗？

sql : insert user values(default,'king','king','email') ，(default,'king2','king','email') 

以前 自增长的 id 没有设置过  unique 这个属性, 这个 '无符号’限制起到什么作用呢？

soyoung1994

2016-04-13

源自：PDO—数据库抽象层  2-2

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qq_慕神1420022
2022-03-30

嗯第二版就是带着你通过OOP来搭建自己的框架，敬请期待，框架的名都有了叫king'sPHP

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多多尘
2016-04-13

unique代表的是唯一值，有点类似primary key，但primary key 一张表只能有一个，而unique可以有多个，unsigned是代表无符号，你可以理解为是没有负号什么的

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soyoung1994 提问者
2016-04-13

上述说错了  是 unsigned

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