怎么删除唯一约束?向大侠求救!! 表名 nnn 列名 myname(可以为空)想删除唯一约束ALTER TABLE nnn drop UNIQUE (myname);删不掉向大侠求救!! 解决方案 » 免费领取超大流量手机卡,每月29元包185G流量+100分钟通话, 中国电信官方发货 show create table nnn;贴一下内容。 来了!!mysql> show create table nnn;+-------+----------------------------------------------------------------------------------------------------------------------------------------+| Table | Create Table |+-------+----------------------------------------------------------------------------------------------------------------------------------------+| nnn | CREATE TABLE `nnn` ( `id` int(11) NOT NULL auto_increment, `myname` varchar(20) default NULL, PRIMARY KEY (`id`), UNIQUE KEY `myname` (`myname`)) ENGINE=InnoDB DEFAULT CHARSET=gb2312 |+-------+----------------------------------------------------------------------------------------------------------------------------------------+1 row in set (0.00 sec) mysql> show create table `nnn`;+-------+------------------------------------| Table | Create Table+-------+------------------------------------| nnn | CREATE TABLE `nnn` ( `id` int(11) NOT NULL AUTO_INCREMENT, `myname` varchar(20) DEFAULT NULL, PRIMARY KEY (`id`), UNIQUE KEY `myname` (`myname`)) ENGINE=InnoDB DEFAULT CHARSET=latin1 |+-------+------------------------------------1 row in set (0.00 sec)mysql> DROP INDEX `myname` ON `nnn`;Query OK, 0 rows affected (0.13 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> show create table `nnn`;+-------+-------------------------------| Table | Create Table+-------+-------------------------------| nnn | CREATE TABLE `nnn` ( `id` int(11) NOT NULL AUTO_INCREMENT, `myname` varchar(20) DEFAULT NULL, PRIMARY KEY (`id`)) ENGINE=InnoDB DEFAULT CHARSET=latin1 |+-------+-------------------------------1 row in set (0.00 sec)mysql> 或者 alter table `nnn` drop `myname`;mysql> show create table `nnn`;+-------+------------------------------------| Table | Create Table+-------+------------------------------------| nnn | CREATE TABLE `nnn` ( `id` int(11) NOT NULL AUTO_INCREMENT, `myname` varchar(20) DEFAULT NULL, PRIMARY KEY (`id`), UNIQUE KEY `myname` (`myname`)) ENGINE=InnoDB DEFAULT CHARSET=latin1 |+-------+------------------------------------1 row in set (0.00 sec)mysql> alter table `nnn` drop `myname`;Query OK, 0 rows affected (0.14 sec)Records: 0 Duplicates: 0 Warnings: 0mysql> show create table `nnn`;+-------+-------------------------------| Table | Create Table+-------+-------------------------------| nnn | CREATE TABLE `nnn` ( `id` int(11) NOT NULL AUTO_INCREMENT, `myname` varchar(20) DEFAULT NULL, PRIMARY KEY (`id`)) ENGINE=InnoDB DEFAULT CHARSET=latin1 |+-------+-------------------------------1 row in set (0.00 sec)mysql> Innodb锁表 一条mysql的查询语句 用转义符\来处理update的问题 ArcGis engine+eclipse java实现 MYSQL用SQL调用文章另外字段的数据?? 如何通过MySql提供的JDBC桥直接进行数据库连接? MySQL4.0.15在那裡下載 mysql 多表查询问题 (急!急!急!急!急!)安装MS Sql Server 7.0 时出现的问题!请大家帮忙! mySQL question mysql 命令行下 显示 中文字符 问题 和 关于数据库 2个 笔试题( 在线等待!) mysql 查询的问题
来了!!
mysql> show create table nnn;
+-------+------------------------------------------
---------------------------------------------------
-------------------------------------------+
| Table | Create Table |
+-------+------------------------------------------
---------------------------------------------------
-------------------------------------------+
| nnn | CREATE TABLE `nnn` (
`id` int(11) NOT NULL auto_increment,
`myname` varchar(20) default NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `myname` (`myname`)
) ENGINE=InnoDB DEFAULT CHARSET=gb2312 |
+-------+------------------------------------------
---------------------------------------------------
-------------------------------------------+
1 row in set (0.00 sec)
+-------+------------------------------------
| Table | Create Table
+-------+------------------------------------
| nnn | CREATE TABLE `nnn` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`myname` varchar(20) DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `myname` (`myname`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+------------------------------------
1 row in set (0.00 sec)mysql> DROP INDEX `myname` ON `nnn`;
Query OK, 0 rows affected (0.13 sec)
Records: 0 Duplicates: 0 Warnings: 0mysql> show create table `nnn`;
+-------+-------------------------------
| Table | Create Table
+-------+-------------------------------
| nnn | CREATE TABLE `nnn` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`myname` varchar(20) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+-------------------------------
1 row in set (0.00 sec)mysql>
+-------+------------------------------------
| Table | Create Table
+-------+------------------------------------
| nnn | CREATE TABLE `nnn` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`myname` varchar(20) DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `myname` (`myname`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+------------------------------------
1 row in set (0.00 sec)mysql> alter table `nnn` drop `myname`;
Query OK, 0 rows affected (0.14 sec)
Records: 0 Duplicates: 0 Warnings: 0mysql> show create table `nnn`;
+-------+-------------------------------
| Table | Create Table
+-------+-------------------------------
| nnn | CREATE TABLE `nnn` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`myname` varchar(20) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+-------------------------------
1 row in set (0.00 sec)mysql>