MySQL是一種常用的關系型數據庫系統,它支持多種編碼。編碼是用于表示文本字符集的方式,MySQL中的編碼稱為字符集(charset),在不同的字符集下,相同的字符可能會有不同的編碼。
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 | ISO 8859-1 Latin 1 | latin1_swedish_ci | 1 | | latin2 | ISO 8859-2 Central European | latin2_general_ci | 1 | | swe7 | 7bit Swedish | swe7_swedish_ci | 1 | | utf8 | UTF-8 Unicode | utf8_general_ci | 3 | | utf8mb4 | UTF-8 Unicode | utf8mb4_general_ci | 4 | | ucs2 | UCS-2 Unicode | ucs2_general_ci | 2 | | 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 | +----------+-----------------------------+---------------------+--------+
MySQL中最常用的字符集是UTF-8,因為它可以支持眾多的語言,包括中文、韓文、日文等等。在使用UTF-8字符集時,需要注意在創建表和插入數據時,要保證字符集一致,否則數據可能無法正確顯示。
mysql>CREATE TABLE `test` ( `id` int(11) NOT NULL AUTO_INCREMENT, `name` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=4 DEFAULT CHARSET=utf8; mysql>INSERT INTO `test` (`id`, `name`) VALUES (1, '測試'), (2, '中文'), (3, 'MySQL'); mysql>SELECT * FROM `test`; +----+--------+ | id | name | +----+--------+ | 1 | 測試 | | 2 | 中文 | | 3 | MySQL | +----+--------+
在處理字符集時,還需要注意一些細節問題。例如,在查詢過程中,字符串比較可能會受到字符集和排序規則的影響。如果需要進行精確匹配或排序,需要使用相應的字符集和排序規則。