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information-schema-collation-character-set-applicability.md

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COLLATION_CHARACTER_SET_APPLICABILITY
了解 INFORMATION_SCHEMA 表 `COLLATION_CHARACTER_SET_APPLICABILITY`。

COLLATION_CHARACTER_SET_APPLICABILITY

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;

输出结果如下：

+--------------------+-------------+------+------+---------+-------+
| 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)

查看 COLLATION_CHARACTER_SET_APPLICABILITY 表中 utf8mb4 字符集的排序规则映射：

SELECT * FROM COLLATION_CHARACTER_SET_APPLICABILITY WHERE character_set_name='utf8mb4';

输出结果如下：

+--------------------+--------------------+
| COLLATION_NAME     | CHARACTER_SET_NAME |
+--------------------+--------------------+
| utf8mb4_bin        | utf8mb4            |
| utf8mb4_general_ci | utf8mb4            |
| utf8mb4_unicode_ci | utf8mb4            |
+--------------------+--------------------+
3 rows 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