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Home Backend Development PHP Tutorial mysql_insert_id的疑问

mysql_insert_id的疑问

Jun 23, 2016 pm 01:55 PM
doubt

CREATE TABLE `create_id` (  `id` int(10) unsigned NOT NULL AUTO_INCREMENT COMMENT '生成自增user_id',  `v` varchar(1) NOT NULL COMMENT '用于生成新的id',  PRIMARY KEY (`id`),  UNIQUE KEY `v` (`v`)) ENGINE=MyISAM  DEFAULT CHARSET=utf8 ;replace into `create_id` set `v`='1' ;
Copy after login

执行这条sql之后,用mysql_insert_id无法获得insert id。有什么方法/函数能获得replace into产生的新id?


回复讨论(解决方案)

replace 指令可能产生,也可能不产生新的 id
所以获取不到是正常的

那么 有什么方法/函数能获得replace into产生的新id?
答案是没有,但你可以指定 id

replace 指令可能产生,也可能不产生新的 id
所以获取不到是正常的

那么 有什么方法/函数能获得replace into产生的新id?
答案是没有,但你可以指定 id



按照我的表结构,且每次均执行同一个sql,也有可能不产生新的id?
v是唯一的,我每次都reaplace into同一个值,id应该会每次都自增1才对呀?

被你忽悠了!
刚才测试了一下,是能取到的

而且我看到php手册里有这么一段提示:
Warning
mysql_insert_id() 将 MySQL 内部的 C API 函数 mysql_insert_id() 的返回值转换成 long(PHP 中命名为 int)。如果 AUTO_INCREMENT 的列的类型是 BIGINT,则 mysql_insert_id() 返回的值将不正确。可以在 SQL 查询中用 MySQL 内部的 SQL 函数 LAST_INSERT_ID() 来替代。

replace into `create_id` set `v`='1';select LAST_INSERT_ID() as `id` from `create_id`;
Copy after login

这样确实能返回最新的id呀。

select LAST_INSERT_ID() as `id` from `create_id`;
?
select id from `create_id` order by id desc limit 1
不是一???

被你忽悠了!
刚才测试了一下,是能取到的



呃。。。我看php手册里面有一个老外这么写到:
athies at gmail dot com 21-Jul-2005 11:36 

 Just a quick note. mysql_insert_id() does work with REPLACE. 

select LAST_INSERT_ID() as `id` from `create_id`;
?
select id from `create_id` order by id desc limit 1
不是一???



并发的情况下, order by id desc 可能就是别人的id了
LAST_INSERT_ID() 是在某个数据库连接的范围内吗?

原来这样也可以获id,学习了

select id from tb  order by id desc limit 1

select id from tb  order by id desc limit 1

这个只可以获取库里面的id吧?楼主是在插入数据的时候,要获取当前id。
我用TP写的:        
        $Form=M('member');
        $sql="show table status where Name='fht_member'";
        $rs=$Form->query($sql);
        $Mid=$rs[0]['Auto_increment'];
返回记录集有个['Auto_increment'],就是当前插入的自增id

后来发现mysql_insert_id()真能取到,感谢各位的踊跃发言

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