MySQL 不允许我更改排序规则类型

Question

我正试图将我的表排序类型从unicode转换为通用，但mysql不允许。没有返回错误，但是当我查看表时，我可以看到没有进行任何更改。

mysql> show variables like '%coll%';
+----------------------+-----------------+
| Variable_name        | Value           |
+----------------------+-----------------+
| collation_connection | utf8_general_ci |
| collation_database   | utf8_unicode_ci |
| collation_server     | utf8_unicode_ci |
+----------------------+-----------------+
3 rows in set (0.00 sec)
mysql> show create table abc;
+----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table    | Create Table                                                                                                                                                                                                      |
+----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| abc_test | CREATE TABLE `abc` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `somecolumn` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci ROW_FORMAT=DYNAMIC |
+----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)
mysql> alter table abc convert to charset utf8 collate utf8_general_ci;
Query OK, 0 rows affected (0.01 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> show create table abc;
+----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table    | Create Table                                                                                                                                                                                                      |
+----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| abc_test | CREATE TABLE `abc` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `somecolumn` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci ROW_FORMAT=DYNAMIC |
+----------+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

Answer 1

就像这样使用alter, ALTER TABLE table_name COLLATE='utf8_general_ci';

您的表已经有UTF8 charset。所以，在我看来，你不需要再设置了。我可以看到，您正试图将其转换为字符集utf8再次与您的alter查询。

Answer 2

我尝试了mysql 5.7.18，一切看起来都很好。你用的是哪个版本?

我设置了与您相同的排序变量，并创建了表，并通过从上面复制的语句更改了排序。最后我得到了:

mysql> show create table abc;
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                       |
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| abc   | CREATE TABLE `abc` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `somecolumn` bigint(20) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC |
+-------+----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.01 sec)
mysql> select version();
+--------------+
| version()    |
+--------------+
| 5.7.18-debug |
+--------------+

SHOW CREATE TABLE不打印排序规则信息，因为utf8_general_ci是utf8的默认排序规则。