关于Mysql建表的长度限制

Question

create table Article (
articleID varchar(255) not null,
articleCotent varchar(255),
articleCreateDate datetime,
articleDescription varchar(255),
articlePV integer,
articlePicUrl varchar(255),
articleTitle varchar(60),
articleType varchar(50),
articleUrl varchar(255),
isShowCover bit,
primary key (articleID)
)
执行以上的建表语句，报错Specified key was too long; max key length is 767 bytes
难道必须要修改表的长度才可以吗？
我的MySql是6.0.11版的

Answer 1

[code="java"]
MySQL是限制长度的， 因为你是设置的UTF-8编码，
articleID 长度是255*4 > 767 的

mysql官方好像有个说明, 如下
MySQL has a prefix limitation of 767 bytes in InnoDB, and 1000 bytes in MyISAM. This has never been a problem for me, until I started using UTF-16 as the character set for one of my databases. UTF-16 can use up to 4 bytes per character which means that in an InnoDB table, you can’t have any keys longer than 191 characters. Take this CREATE statement for example:

CREATE TABLE user (
id int(11) NOT NULL AUTO_INCREMENT,
username varchar(32) NOT NULL,
password varchar(64) NOT NULL,
email varchar(255) NOT NULL,
PRIMARY KEY (id),
UNIQUE KEY UNIQ_8D93D649F85E0677 (username),
UNIQUE KEY UNIQ_8D93D649E7927C74 (email)
) ENGINE=InnoDB DEFAULT CHARSET=utf16 AUTO_INCREMENT=1 ;
This will fail with an error like Specified key was too long; max key length is 767 bytes, because the UNIQUE INDEX on the email field requires at least 1020 bytes (255 * 4).
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