mysql 怎么删除唯一约束？

[qx8668]

表名 nnn 列名 myname（可以为空）

想删除唯一约束

[--小F--]

MYSQL有请小梁

[qx8668]

Google找了半天，很无力～～，只找到创建，没找到删除

真是只管结婚不管生孩子～～～～

[ACMAIN_CHM]

show create table nnn;

贴一下内容。

[qx8668]

[Quote=引用 3 楼 acmain_chm 的回复:]
show create table nnn;

贴一下内容。
[/Quote]
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)

大哥，我找你好久了

[ACMAIN_CHM]

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: 0

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`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+-------------------------------
1 row in set (0.00 sec)

mysql>

[ACMAIN_CHM]

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: 0

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`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 |
+-------+-------------------------------
1 row in set (0.00 sec)

mysql>

[qx8668]

[Quote=引用 5 楼 acmain_chm 的回复:]
SQL codemysql> showcreatetable `nnn`;+-------+------------------------------------|Table|CreateTable+-------+------------------------------------| nnn|CREATETABLE `nnn` (
`id`int(11)NOTNULL AUTO_INC¡­
[/Quote]

小菜不理解为什么删除INDEX，不是创建唯一约束了吗。。