MySQL の文字エンコーディングと照合順序の設定を確認する

## 公式ドキュメントの情報

[MySQL :: MySQL 5\.6 リファレンスマニュアル :: 10\.1\.4 接続文字セットおよび照合順序](https://dev.mysql.com/doc/refman/5.6/ja/charset-connection.html)

> 接続に適用する文字セットおよび照合順序システム変数の値を確認するには、次のステートメントを使用してください。
> 
> SHOW VARIABLES LIKE 'character_set%';
> SHOW VARIABLES LIKE 'collation%';

## MySQL monitor から実行する例

```
mysql> show variables like 'character%';
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |
| character_set_database   | utf8mb4                    |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | utf8mb4                    |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+
8 rows in set (0.01 sec)
```

```
mysql> show variables like 'collation%';
+----------------------+--------------------+
| Variable_name        | Value              |
+----------------------+--------------------+
| collation_connection | utf8_general_ci    |
| collation_database   | utf8mb4_general_ci |
| collation_server     | utf8mb4_general_ci |
+----------------------+--------------------+
3 rows in set (0.00 sec)
```

## シェルから実行する例

```
$ echo "show variables like 'character%'; show variables like 'collation%';" | mysql -u your-account-name -p
Enter password: 
Variable_name	Value
character_set_client	utf8
character_set_connection	utf8
character_set_database	utf8mb4
character_set_filesystem	binary
character_set_results	utf8
character_set_server	utf8mb4
character_set_system	utf8
character_sets_dir	/usr/share/mysql/charsets/
Variable_name	Value
collation_connection	utf8_general_ci
collation_database	utf8mb4_general_ci
collation_server	utf8mb4_general_ci
```

## 使用可能な文字エンコーディング一覧

show character set で使用可能な文字エンコーディングのリストを確認できる。

```
mysql> show character set;
+----------+---------------------------------+---------------------+--------+
| Charset  | Description                     | Default collation   | Maxlen |
+----------+---------------------------------+---------------------+--------+
| big5     | Big5 Traditional Chinese        | big5_chinese_ci     |      2 |
| dec8     | DEC West European               | dec8_swedish_ci     |      1 |
| cp850    | DOS West European               | cp850_general_ci    |      1 |
| hp8      | HP West European                | hp8_english_ci      |      1 |
| koi8r    | KOI8-R Relcom Russian           | koi8r_general_ci    |      1 |
| latin1   | cp1252 West European            | latin1_swedish_ci   |      1 |
| latin2   | ISO 8859-2 Central European     | latin2_general_ci   |      1 |
| swe7     | 7bit Swedish                    | swe7_swedish_ci     |      1 |
| ascii    | US ASCII                        | ascii_general_ci    |      1 |
| ujis     | EUC-JP Japanese                 | ujis_japanese_ci    |      3 |
| sjis     | Shift-JIS Japanese              | sjis_japanese_ci    |      2 |
| hebrew   | ISO 8859-8 Hebrew               | hebrew_general_ci   |      1 |
| tis620   | TIS620 Thai                     | tis620_thai_ci      |      1 |
| euckr    | EUC-KR Korean                   | euckr_korean_ci     |      2 |
| koi8u    | KOI8-U Ukrainian                | koi8u_general_ci    |      1 |
| gb2312   | GB2312 Simplified Chinese       | gb2312_chinese_ci   |      2 |
| greek    | ISO 8859-7 Greek                | greek_general_ci    |      1 |
| cp1250   | Windows Central European        | cp1250_general_ci   |      1 |
| gbk      | GBK Simplified Chinese          | gbk_chinese_ci      |      2 |
| latin5   | ISO 8859-9 Turkish              | latin5_turkish_ci   |      1 |
| armscii8 | ARMSCII-8 Armenian              | armscii8_general_ci |      1 |
| utf8     | UTF-8 Unicode                   | utf8_general_ci     |      3 |
| ucs2     | UCS-2 Unicode                   | ucs2_general_ci     |      2 |
| cp866    | DOS Russian                     | cp866_general_ci    |      1 |
| keybcs2  | DOS Kamenicky Czech-Slovak      | keybcs2_general_ci  |      1 |
| macce    | Mac Central European            | macce_general_ci    |      1 |
| macroman | Mac West European               | macroman_general_ci |      1 |
| cp852    | DOS Central European            | cp852_general_ci    |      1 |
| latin7   | ISO 8859-13 Baltic              | latin7_general_ci   |      1 |
| utf8mb4  | UTF-8 Unicode                   | utf8mb4_general_ci  |      4 |
| cp1251   | Windows Cyrillic                | cp1251_general_ci   |      1 |
| utf16    | UTF-16 Unicode                  | utf16_general_ci    |      4 |
| utf16le  | UTF-16LE Unicode                | utf16le_general_ci  |      4 |
| cp1256   | Windows Arabic                  | cp1256_general_ci   |      1 |
| cp1257   | Windows Baltic                  | cp1257_general_ci   |      1 |
| utf32    | UTF-32 Unicode                  | utf32_general_ci    |      4 |
| binary   | Binary pseudo charset           | binary              |      1 |
| geostd8  | GEOSTD8 Georgian                | geostd8_general_ci  |      1 |
| cp932    | SJIS for Windows Japanese       | cp932_japanese_ci   |      2 |
| eucjpms  | UJIS for Windows Japanese       | eucjpms_japanese_ci |      3 |
| gb18030  | China National Standard GB18030 | gb18030_chinese_ci  |      4 |
+----------+---------------------------------+---------------------+--------+
41 rows in set (0.00 sec)
```

## 参考資料

- [MySQL :: MySQL 5\.6 リファレンスマニュアル :: 10\.1\.4 接続文字セットおよび照合順序](https://dev.mysql.com/doc/refman/5.6/ja/charset-connection.html)
- [MySQL :: MySQL 5\.6 リファレンスマニュアル :: 10\.1\.14 MySQL でサポートされる文字セットと照合順序](https://dev.mysql.com/doc/refman/5.6/ja/charset-charsets.html)
- [MySQL :: MySQL 5\.6 リファレンスマニュアル :: 10\.1\.14\.1 Unicode 文字セット](https://dev.mysql.com/doc/refman/5.6/ja/charset-unicode-sets.html)
- [MySQL :: MySQL 5\.6 リファレンスマニュアル :: 5\.1\.4 サーバーシステム変数](https://dev.mysql.com/doc/refman/5.6/ja/server-system-variables.html)
- [MySQL :: MySQL 5\.6 リファレンスマニュアル :: 13\.7\.5\.40 SHOW VARIABLES 構文](https://dev.mysql.com/doc/refman/5.6/ja/show-variables.html)