MySQL表排序规则不同错误问题分析
网络编程 2021-07-05 14:36www.168986.cn编程入门
这篇文章主要介绍了MySQL表排序规则不同错误问题分析,长沙网络推广觉得挺不错的,这里分享给大家,供各位参考。
多表join时报错如下:[Err]1267 – Illegal mix of collations(utf8_general_ci,IMPLICIT) and (utf8_unicode_ci,IMPLICIT) for operation ‘=
就是说两个表的排序规则(COLLATION)不同,无法完成比较。COLLATION是用在排序,大小比较上,一个字符集有一个或多种COLLATION,并且以_ci(大小写不敏感)、_cs(大小写敏感)或_bin(二进制)结束。在做比较时,应该确保两个表的字符排序相同。一般建表的时候不指定,可以走默认的,全是默认的就没什么问题了。
狼蚁网站SEO优化来模拟一下各种场景,表结构如下(utf8默认排序规则为utf8_general_ci):
mysql> show create table test.cs\G *************************** 1. row *************************** Table: cs Create Table: CREATE TABLE `cs` ( `id` int(11) DEFAULT NULL, `name` varchar(10) DEFAULT NULL ) ENGINE=InnoDB DEFAULT CHARSET=utf8 1 row in set (0.01 sec)
查看表默认排序规则集
mysql> select TABLE_SCHEMA,TABLE_NAME,TABLE_COLLATION from information_schema.tables where table_name='cs'; +--------------+------------+-----------------+ | TABLE_SCHEMA | TABLE_NAME | TABLE_COLLATION | +--------------+------------+-----------------+ | test | cs | utf8_general_ci | +--------------+------------+-----------------+ 1 row in set (0.00 sec)
查看列排序规则集
mysql> select TABLE_SCHEMA,TABLE_NAME,COLUMN_NAME,COLLATION_NAME from information_schema.COLUMNS where TABLE_NAME='cs'; +--------------+------------+-------------+-----------------+ | TABLE_SCHEMA | TABLE_NAME | COLUMN_NAME | COLLATION_NAME | +--------------+------------+-------------+-----------------+ | test | cs | id | NULL | | test | cs | name | utf8_general_ci | +--------------+------------+-------------+-----------------+ 2 rows in set (0.00 sec)
从utf8升级为utf8mb4是不支持online ddl的,如下:
mysql> ALTER TABLE cs CONVERT TO CHARACTER SET utf8mb4,ALGORITHM=INPLACE,LOCK=NONE; ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY.
从utf8.utf8_general_ci变更为utf8.utf8_unicode_ci是不支持online ddl的,如下:
mysql> ALTER TABLE cs CONVERT TO CHARACTER SET utf8 collate utf8_unicode_ci,ALGORITHM=INPLACE,LOCK=NONE; ERROR 1846 (0A000): ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY.
如果使用狼蚁网站SEO优化这种方式修改字符集,你会发现,只更改了表级的,没有更改列级的。
mysql> ALTER TABLE cs CHARACTER SET utf8 collate utf8_unicode_ci; Query OK, 0 rows affected (0.01 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> select TABLE_SCHEMA,TABLE_NAME,TABLE_COLLATION from information_schema.tables where table_name='cs'; +--------------+------------+-----------------+ | TABLE_SCHEMA | TABLE_NAME | TABLE_COLLATION | +--------------+------------+-----------------+ | test | cs | utf8_unicode_ci | +--------------+------------+-----------------+ 1 row in set (0.00 sec) mysql> select TABLE_SCHEMA,TABLE_NAME,COLUMN_NAME,COLLATION_NAME from information_schema.COLUMNS where TABLE_NAME='cs'; +--------------+------------+-------------+-----------------+ | TABLE_SCHEMA | TABLE_NAME | COLUMN_NAME | COLLATION_NAME | +--------------+------------+-------------+-----------------+ | test | cs | id | NULL | | test | cs | name | utf8_general_ci | +--------------+------------+-------------+-----------------+ 2 rows in set (0.00 sec)
所以真正改字符集的时候别忘了加上CONVERT TO,如下:
mysql> ALTER TABLE cs CONVERT TO CHARACTER SET utf8 collate utf8_unicode_ci; Query OK, 5 rows affected (0.06 sec) Records: 5 Duplicates: 0 Warnings: 0 mysql> select TABLE_SCHEMA,TABLE_NAME,COLUMN_NAME,COLLATION_NAME from information_schema.COLUMNS where TABLE_NAME='cs'; +--------------+------------+-------------+-----------------+ | TABLE_SCHEMA | TABLE_NAME | COLUMN_NAME | COLLATION_NAME | +--------------+------------+-------------+-----------------+ | test | cs | id | NULL | | test | cs | name | utf8_unicode_ci | +--------------+------------+-------------+-----------------+ 2 rows in set (0.00 sec)
要仅仅改变一个表的默认字符集,应使用此语句:
mysql> ALTER TABLE cs default CHARACTER SET utf8 collate utf8_general_ci,ALGORITHM=INPLACE,LOCK=NONE; Query OK, 0 rows affected (0.00 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> select TABLE_SCHEMA,TABLE_NAME,TABLE_COLLATION from information_schema.tables where table_name='cs'; +--------------+------------+-----------------+ | TABLE_SCHEMA | TABLE_NAME | TABLE_COLLATION | +--------------+------------+-----------------+ | test | cs | utf8_general_ci | +--------------+------------+-----------------+ 1 row in set (0.00 sec) mysql> select TABLE_SCHEMA,TABLE_NAME,COLUMN_NAME,COLLATION_NAME from information_schema.COLUMNS where TABLE_NAME='cs'; +--------------+------------+-------------+-----------------+ | TABLE_SCHEMA | TABLE_NAME | COLUMN_NAME | COLLATION_NAME | +--------------+------------+-------------+-----------------+ | test | cs | id | NULL | | test | cs | name | utf8_unicode_ci | +--------------+------------+-------------+-----------------+ 2 rows in set (0.00 sec)
可以发现列字符集没有改变,并且只有新的列才会默认继承表的字符集(utf8.utf8_general_ci)。
总结
以上就是本文关于MySQL表排序规则不同错误问题分析的全部内容,希望对大家有所帮助。感兴趣的朋友可以参阅:、、、等,有什么问题可以随时留言,互相交流,共同进步。
编程语言
- 机械手焊接机器人编程 机械手焊接设备编程
- vb数据库编程实例,vb做数据库
- tiobe世界编程语言排行榜,全球编程语言排行
- 成都java编程培训 成都it编程培训中心
- 编程基础培训,编程基础知识培训
- flash游戏编程基础教程,flash游戏开发教程
- 不会英语能学编程吗 不会英语可以学程序员吗
- 爱心代码编程C语言 爱心代码编程c语言公式
- c语言编程学习入门 c语言编程快速入门
- 西门子plc编程培训 西门子plc编程培训班
- 哪里可以学编程 台州哪里可以学编程
- 少儿编程哪个好 少儿编程哪个品牌好
- 编程是什么意思,图形编程是什么意思
- c语言编程软件下载,c语言编程软件在哪下载
- java编程软件下载,java编程下载手机版
- ug编程培训学校,ug编程培训教程