Question

COLLATION_CHARACTER_SET_APPLICABILITY 表将排序规则映射至适用的字符集名称。和 COLLATIONS 表一样，包含此表只是为了兼容 MySQL。

USE information_schema;
DESC collation_character_set_applicability;

+--------------------+-------------+------+------+---------+-------+
| Field              | Type        | Null | Key  | Default | Extra |
+--------------------+-------------+------+------+---------+-------+
| COLLATION_NAME     | varchar(32) | NO   |      | NULL    |       |
| CHARACTER_SET_NAME | varchar(32) | NO   |      | NULL    |       |
+--------------------+-------------+------+------+---------+-------+
2 rows in set (0.00 sec)

SELECT * FROM collation_character_set_applicability WHERE character_set_name='utf8mb4';

+----------------+--------------------+
| COLLATION_NAME | CHARACTER_SET_NAME |
+----------------+--------------------+
| utf8mb4_bin    | utf8mb4            |
+----------------+--------------------+
1 row in set (0.00 sec)

COLLATION_CHARACTER_SET_APPLICABILITY 表中列的含义如下：

• COLLATION_NAME：排序规则名称
• CHARACTER_SET_NAME：排序规则所属的字符集名称