重复的键名'unique_id'

Question

这是sql,但是,有一个错误说" *#1061 - 重复键名'unique_id'* ",有什么问题.

create table `users`(
   uid int(11) auto_increment,
   unique_id varchar(23) not null unique,
   name varchar(50) not null,
   email varchar(100) not null unique,
   encrypted_password varchar(80) not null,
   salt varchar(10) not null,
   created_at datetime,
   updated_at datetime null,
  PRIMARY KEY (`unique_id`),
  UNIQUE KEY `uid` (`uid`),
  UNIQUE KEY `unique_id` (`unique_id`),
  UNIQUE KEY `email` (`email`)
)ENGINE=InnoDB AUTO_INCREMENT=877888 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

Answer 1

删除此行

UNIQUE KEY `unique_id` (`unique_id`),

既然unique_id已经Primary Key.并且Primary Keys是独一无二的.

完整的CREATE TABLE声明

create table `users`
(
   uid int(11) auto_increment,
   unique_id varchar(23) not null,
   name varchar(50) not null,
   email varchar(100) not null unique,   -- specified here
   encrypted_password varchar(80) not null,
   salt varchar(10) not null,
   created_at datetime,
   updated_at datetime null,
   PRIMARY KEY (`unique_id`),
   UNIQUE KEY `uid` (`uid`)
)  ENGINE=InnoDB AUTO_INCREMENT=877888 
DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

• SQLFiddle演示