CHARACTER_SETS

• 该表提供查询MySQL Server支持的可用字符集有哪些

• 该表是Memory引擎临时表

• 表定义语句

CREATE TEMPORARY TABLE `CHARACTER_SETS` (
  `CHARACTER_SET_NAME` varchar(32) NOT NULL DEFAULT '',
  `DEFAULT_COLLATE_NAME` varchar(32) NOT NULL DEFAULT '',
  `DESCRIPTION` varchar(60) NOT NULL DEFAULT '',
  `MAXLEN` bigint(3) NOT NULL DEFAULT '0'
) ENGINE=MEMORY DEFAULT CHARSET=utf8

• 字段含义

• CHARACTER_SET_NAME：字符集名称
• DEFAULT_COLLATE_NAME：字符集对应的默认校对规则
• DESCRIPTION：字符集描述信息，该字段为 "MySQL extension" 列
• MAXLEN：字符集单个字符占用的最大字节数，该字段为 "MySQL extension" 列

• 表记录完整字段内容示例（MySQL 5.6版本支持40种字符集，5.7开始增加了gb18030 字符集）

admin@localhost : information_schema 03:31:08> select * from CHARACTER_SETS;
+--------------------+----------------------+---------------------------------+--------+
| CHARACTER_SET_NAME | DEFAULT_COLLATE_NAME | DESCRIPTION                    | MAXLEN |
+--------------------+----------------------+---------------------------------+--------+
............
| latin1            | latin1_swedish_ci    | cp1252 West European            |      1 |
| latin2            | latin2_general_ci    | ISO 8859-2 Central European    |      1 |
| swe7              | swe7_swedish_ci      | 7bit Swedish                    |      1 |
| ascii              | ascii_general_ci    | US ASCII                        |      1 |
............
| utf8              | utf8_general_ci      | UTF-8 Unicode                  |      3 |
............
| gb18030            | gb18030_chinese_ci  | China National Standard GB18030 |      4 |
+--------------------+----------------------+---------------------------------+--------+
41 rows in set (0.00 sec)

• 对于字符集的信息方式有两种

# select语句方式
SELECT * FROM INFORMATION_SCHEMA.CHARACTER_SETS
  [WHERE CHARACTER_SET_NAME LIKE 'wild']

## 例如
root@localhost : (none) 12:02:02> SELECT * FROM INFORMATION_SCHEMA.CHARACTER_SETS where  CHARACTER_SET_NAME LIKE 'utf8%';
+--------------------+----------------------+---------------+--------+
| CHARACTER_SET_NAME | DEFAULT_COLLATE_NAME | DESCRIPTION  | MAXLEN |
+--------------------+----------------------+---------------+--------+
| utf8              | utf8_general_ci      | UTF-8 Unicode |      3 |
| utf8mb4            | utf8mb4_general_ci  | UTF-8 Unicode |      4 |
+--------------------+----------------------+---------------+--------+
2 rows in set (0.00 sec)

# show语句方式
SHOW CHARACTER SET
  [LIKE 'wild']

## 例如
root@localhost : (none) 12:02:04> SHOW CHARACTER SET like 'utf8%';
+---------+---------------+--------------------+--------+
| Charset | Description  | Default collation  | Maxlen |
+---------+---------------+--------------------+--------+
| utf8    | UTF-8 Unicode | utf8_general_ci    |      3 |
| utf8mb4 | UTF-8 Unicode | utf8mb4_general_ci |      4 |
+---------+---------------+--------------------+--------+
2 rows in set (0.00 sec)

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