我们经常能在数据库中看到这些: utf8mb4 和 utf8, utf8mb4_unicode_ci, utf8mb4_general_ci, utf8mb4_bin 分别代表什么意思呢?
其实他们表示的是字符集 和 排序规则
字符集：就是用来定义字符在数据库中的编码的集合。 排序规则：用来定义比较字符串的方式。 字符集和排序规则是一对多的关系
一 MySQL 支持多个 Unicode 字符集
utf8mb4: Unicode 字符集的 UTF-8 编码, 每个字符使用 1-4 个字节, mb4 即 most bytes 4
utf8mb3: Unicode 字符集的 UTF-8 编码, 每个字符使用 1-3 个字节. MySQL 8.0 中不推荐使用此字符集, 应改用utf8mb4
ucs2: Unicode 字符集的 UCS-2 编码, 每个字符使用 2 个字节. MySQL 8.0.28 中已弃用, 您应该希望在将来的版本中删除对该字符集的支持
utf16: Unicode字符集的 UTF-16 编码, 每个字符使用 2-4 字节. 与 ucs2 类似, 但具有补充字符的扩展名
utf16le: Unicode 字符集的 UTF-16LE 编码. 像 utf16, 但小端序而不是大端序
utf32: Unicode 字符集的 UTF-32 编码, 每个字符使用 4 个字节
utf8: 是utf8mb3 的别名, 节省空间但不能表达全部的UTF-8 (比如emoji表情). MySQL 的 utf8 实际上不是真正的 UTF-8. 在 MySQL 8.0 中, 此别名已弃用, 改用utf8mb4, utf8 有望在未来的版本中成为 utf8mb4 的别名. 从 MySQL 8.0.28 开始, 在信息模式表的列和 SQL SHOW 语句的输出中, utf8mb3也显示在utf8的位置.
utf8mb4 utf16 utf16le 和 utf32 支持BMP(Basic Multilingual Plane: 基本多语言平面)字符和位于BMP之外的补充字符. utf8mb3 和 ucs2 仅支持 BMP 字符
utf8mb4 是 utf8mb3 的超集
推荐
为了避免 utf8 含义的歧义, 请考虑为字符集引用显式指定 utf8mb4
二 排序规则
大多数Unicode字符集都有一个通用排序规则(由名称中的_general表示, 或由缺少语言说明符表示), 一个二进制排序规则(名称中的_bin表示)和几个特定于语言的排序规则(通过语言说明符指示).
例如, 对于utf8mb4, utf8mb4_general_ci 和 utf8mb 4_bin 是其通用和二进制排序规则, 而 utf8mb4_unicode_ci 是其特定语言的排序规则之一
大多数字符集都有一个二进制排序规则, utf8mb4 是一个例外, 它有两个: utf8mb4_bin 和 utf8mb4_0900_bin(从MySQL 8.0.17起) 这两个二进制排序规则具有相同的排序顺序, 但通过其 pad 属性和排序权重特性进行区分
utf8mb4_general_ci 和 utf8mb4_unicode_ci 对比
从准确性比较:
utf8mb4_unicode_ci 是基于标准的 Unicode 来排序和比较, 能够在各种语言之间精确排序
utf8mb4_general_ci 没有实现 Unicode 排序规则, 在遇到某些特殊语言或者字符集, 排序结果可能不一致. 但在绝大多数情况下, 这些特殊字符的顺序并不需要那么精确
从性能比较:
utf8mb4_general_ci 在比较和排序的时候更快
utf8mb4_unicode_ci 在特殊情况下, Unicode 排序规则为了能够处理特殊字符的情况, 实现了略微复杂的排序算法. 但是在绝大多数情况不会发生此类复杂比较
utf8mb4_0900_ai_ci 和 utf8mb4_bin
utf8mb4_0900_ai_ci: 0900代表Unicode 9.0的规范, ai表示 accent insensitivity(不区分音调), 而ci表示case insensitivity(不区分大小写) 而 as 区分音调 cs 表示区分大小写
utf8mb4_bin: 将字符串每个字符用二进制数据编译存储, 区分大小写, 而且可以存二进制的内容
8.0之后默认不再像之前版本一样是utf8mb4_general_ci 而是统一更新成了utf8mb4_0900_ai_ci
推荐
utf8mb4_0900_ai_ci(默认值) 或 utf8mb4_bin
三 字符集和排序规则怎么看
首先查看支持的字符集和排序规则
MySQL不同版本支持的字符集有所不同，可以使用show charset 和 show collation 查看
mysql> show charset;
+----------+---------------------------------+---------------------+--------+
| Charset | Description | Default collation | Maxlen |
+----------+---------------------------------+---------------------+--------+
| armscii8 | ARMSCII-8 Armenian | armscii8_general_ci | 1 |
| ascii | US ASCII | ascii_general_ci | 1 |
| big5 | Big5 Traditional Chinese | big5_chinese_ci | 2 |
| binary | Binary pseudo charset | binary | 1 |
| cp1250 | Windows Central European | cp1250_general_ci | 1 |
| cp1251 | Windows Cyrillic | cp1251_general_ci | 1 |
| cp1256 | Windows Arabic | cp1256_general_ci | 1 |
| cp1257 | Windows Baltic | cp1257_general_ci | 1 |
| cp850 | DOS West European | cp850_general_ci | 1 |
| cp852 | DOS Central European | cp852_general_ci | 1 |
| cp866 | DOS Russian | cp866_general_ci | 1 |
| cp932 | SJIS for Windows Japanese | cp932_japanese_ci | 2 |
| dec8 | DEC West European | dec8_swedish_ci | 1 |
| eucjpms | UJIS for Windows Japanese | eucjpms_japanese_ci | 3 |
| euckr | EUC-KR Korean | euckr_korean_ci | 2 |
| gb18030 | China National Standard GB18030 | gb18030_chinese_ci | 4 |
| gb2312 | GB2312 Simplified Chinese | gb2312_chinese_ci | 2 |
| gbk | GBK Simplified Chinese | gbk_chinese_ci | 2 |
| geostd8 | GEOSTD8 Georgian | geostd8_general_ci | 1 |
| greek | ISO 8859-7 Greek | greek_general_ci | 1 |
| hebrew | ISO 8859-8 Hebrew | hebrew_general_ci | 1 |
| hp8 | HP West European | hp8_english_ci | 1 |
| keybcs2 | DOS Kamenicky Czech-Slovak | keybcs2_general_ci | 1 |
| koi8r | KOI8-R Relcom Russian | koi8r_general_ci | 1 |
| koi8u | KOI8-U Ukrainian | koi8u_general_ci | 1 |
| latin1 | cp1252 West European | latin1_swedish_ci | 1 |
| latin2 | ISO 8859-2 Central European | latin2_general_ci | 1 |
| latin5 | ISO 8859-9 Turkish | latin5_turkish_ci | 1 |
| latin7 | ISO 8859-13 Baltic | latin7_general_ci | 1 |
| macce | Mac Central European | macce_general_ci | 1 |
| macroman | Mac West European | macroman_general_ci | 1 |
| sjis | Shift-JIS Japanese | sjis_japanese_ci | 2 |
| swe7 | 7bit Swedish | swe7_swedish_ci | 1 |
| tis620 | TIS620 Thai | tis620_thai_ci | 1 |
| ucs2 | UCS-2 Unicode | ucs2_general_ci | 2 |
| ujis | EUC-JP Japanese | ujis_japanese_ci | 3 |
| utf16 | UTF-16 Unicode | utf16_general_ci | 4 |
| utf16le | UTF-16LE Unicode | utf16le_general_ci | 4 |
| utf32 | UTF-32 Unicode | utf32_general_ci | 4 |
| utf8 | UTF-8 Unicode | utf8_general_ci | 3 |
| utf8mb4 | UTF-8 Unicode | utf8mb4_0900_ai_ci | 4 |
+----------+---------------------------------+---------------------+--------+
41 rows in set (0.01 sec)
mysql> show collation;
+----------------------------+----------+-----+---------+----------+---------+---------------+
| Collation | Charset | Id | Default | Compiled | Sortlen | Pad_attribute |
+----------------------------+----------+-----+---------+----------+---------+---------------+
| armscii8_bin | armscii8 | 64 | | Yes | 1 | PAD SPACE |
| armscii8_general_ci | armscii8 | 32 | Yes | Yes | 1 | PAD SPACE |
| ascii_bin | ascii | 65 | | Yes | 1 | PAD SPACE |
| ascii_general_ci | ascii | 11 | Yes | Yes | 1 | PAD SPACE |
| big5_bin | big5 | 84 | | Yes | 1 | PAD SPACE |
| big5_chinese_ci | big5 | 1 | Yes | Yes | 1 | PAD SPACE |
| binary | binary | 63 | Yes | Yes | 1 | NO PAD |
| cp1250_bin | cp1250 | 66 | | Yes | 1 | PAD SPACE |
| cp1250_croatian_ci | cp1250 | 44 | | Yes | 1 | PAD SPACE |
| cp1250_czech_cs | cp1250 | 34 | | Yes | 2 | PAD SPACE |
| cp1250_general_ci | cp1250 | 26 | Yes | Yes | 1 | PAD SPACE |
| cp1250_polish_ci | cp1250 | 99 | | Yes | 1 | PAD SPACE |
| cp1251_bin | cp1251 | 50 | | Yes | 1 | PAD SPACE |
| cp1251_bulgarian_ci | cp1251 | 14 | | Yes | 1 | PAD SPACE |
| cp1251_general_ci | cp1251 | 51 | Yes | Yes | 1 | PAD SPACE |
| cp1251_general_cs | cp1251 | 52 | | Yes | 1 | PAD SPACE |
| cp1251_ukrainian_ci | cp1251 | 23 | | Yes | 1 | PAD SPACE |
| cp1256_bin | cp1256 | 67 | | Yes | 1 | PAD SPACE |
| cp1256_general_ci | cp1256 | 57 | Yes | Yes | 1 | PAD SPACE |
| cp1257_bin | cp1257 | 58 | | Yes | 1 | PAD SPACE |
| cp1257_general_ci | cp1257 | 59 | Yes | Yes | 1 | PAD SPACE |
| cp1257_lithuanian_ci | cp1257 | 29 | | Yes | 1 | PAD SPACE |
| cp850_bin | cp850 | 80 | | Yes | 1 | PAD SPACE |
| cp850_general_ci | cp850 | 4 | Yes | Yes | 1 | PAD SPACE |
| cp852_bin | cp852 | 81 | | Yes | 1 | PAD SPACE |
| cp852_general_ci | cp852 | 40 | Yes | Yes | 1 | PAD SPACE |
| cp866_bin | cp866 | 68 | | Yes | 1 | PAD SPACE |
| cp866_general_ci | cp866 | 36 | Yes | Yes | 1 | PAD SPACE |
| cp932_bin | cp932 | 96 | | Yes | 1 | PAD SPACE |
| cp932_japanese_ci | cp932 | 95 | Yes | Yes | 1 | PAD SPACE |
| dec8_bin | dec8 | 69 | | Yes | 1 | PAD SPACE |
| dec8_swedish_ci | dec8 | 3 | Yes | Yes | 1 | PAD SPACE |
| eucjpms_bin | eucjpms | 98 | | Yes | 1 | PAD SPACE |
| eucjpms_japanese_ci | eucjpms | 97 | Yes | Yes | 1 | PAD SPACE |
| euckr_bin | euckr | 85 | | Yes | 1 | PAD SPACE |
| euckr_korean_ci | euckr | 19 | Yes | Yes | 1 | PAD SPACE |
| gb18030_bin | gb18030 | 249 | | Yes | 1 | PAD SPACE |
| gb18030_chinese_ci | gb18030 | 248 | Yes | Yes | 2 | PAD SPACE |
| gb18030_unicode_520_ci | gb18030 | 250 | | Yes | 8 | PAD SPACE |
| gb2312_bin | gb2312 | 86 | | Yes | 1 | PAD SPACE |
| gb2312_chinese_ci | gb2312 | 24 | Yes | Yes | 1 | PAD SPACE |
| gbk_bin | gbk | 87 | | Yes | 1 | PAD SPACE |
| gbk_chinese_ci | gbk | 28 | Yes | Yes | 1 | PAD SPACE |
| geostd8_bin | geostd8 | 93 | | Yes | 1 | PAD SPACE |
| geostd8_general_ci | geostd8 | 92 | Yes | Yes | 1 | PAD SPACE |
| greek_bin | greek | 70 | | Yes | 1 | PAD SPACE |
| greek_general_ci | greek | 25 | Yes | Yes | 1 | PAD SPACE |
| hebrew_bin | hebrew | 71 | | Yes | 1 | PAD SPACE |
| hebrew_general_ci | hebrew | 16 | Yes | Yes | 1 | PAD SPACE |
| hp8_bin | hp8 | 72 | | Yes | 1 | PAD SPACE |
| hp8_english_ci | hp8 | 6 | Yes | Yes | 1 | PAD SPACE |
| keybcs2_bin | keybcs2 | 73 | | Yes | 1 | PAD SPACE |
| keybcs2_general_ci | keybcs2 | 37 | Yes | Yes | 1 | PAD SPACE |
| koi8r_bin | koi8r | 74 | | Yes | 1 | PAD SPACE |
| koi8r_general_ci | koi8r | 7 | Yes | Yes | 1 | PAD SPACE |
| koi8u_bin | koi8u | 75 | | Yes | 1 | PAD SPACE |
| koi8u_general_ci | koi8u | 22 | Yes | Yes | 1 | PAD SPACE |
| latin1_bin | latin1 | 47 | | Yes | 1 | PAD SPACE |
| latin1_danish_ci | latin1 | 15 | | Yes | 1 | PAD SPACE |
| latin1_general_ci | latin1 | 48 | | Yes | 1 | PAD SPACE |
| latin1_general_cs | latin1 | 49 | | Yes | 1 | PAD SPACE |
| latin1_german1_ci | latin1 | 5 | | Yes | 1 | PAD SPACE |
| latin1_german2_ci | latin1 | 31 | | Yes | 2 | PAD SPACE |
| latin1_spanish_ci | latin1 | 94 | | Yes | 1 | PAD SPACE |
| latin1_swedish_ci | latin1 | 8 | Yes | Yes | 1 | PAD SPACE |
| latin2_bin | latin2 | 77 | | Yes | 1 | PAD SPACE |
| latin2_croatian_ci | latin2 | 27 | | Yes | 1 | PAD SPACE |
| latin2_czech_cs | latin2 | 2 | | Yes | 4 | PAD SPACE |
| latin2_general_ci | latin2 | 9 | Yes | Yes | 1 | PAD SPACE |
| latin2_hungarian_ci | latin2 | 21 | | Yes | 1 | PAD SPACE |
| latin5_bin | latin5 | 78 | | Yes | 1 | PAD SPACE |
| latin5_turkish_ci | latin5 | 30 | Yes | Yes | 1 | PAD SPACE |
| latin7_bin | latin7 | 79 | | Yes | 1 | PAD SPACE |
| latin7_estonian_cs | latin7 | 20 | | Yes | 1 | PAD SPACE |
| latin7_general_ci | latin7 | 41 | Yes | Yes | 1 | PAD SPACE |
| latin7_general_cs | latin7 | 42 | | Yes | 1 | PAD SPACE |
| macce_bin | macce | 43 | | Yes | 1 | PAD SPACE |
| macce_general_ci | macce | 38 | Yes | Yes | 1 | PAD SPACE |
| macroman_bin | macroman | 53 | | Yes | 1 | PAD SPACE |
| macroman_general_ci | macroman | 39 | Yes | Yes | 1 | PAD SPACE |
| sjis_bin | sjis | 88 | | Yes | 1 | PAD SPACE |
| sjis_japanese_ci | sjis | 13 | Yes | Yes | 1 | PAD SPACE |
| swe7_bin | swe7 | 82 | | Yes | 1 | PAD SPACE |
| swe7_swedish_ci | swe7 | 10 | Yes | Yes | 1 | PAD SPACE |
| tis620_bin | tis620 | 89 | | Yes | 1 | PAD SPACE |
| tis620_thai_ci | tis620 | 18 | Yes | Yes | 4 | PAD SPACE |
| ucs2_bin | ucs2 | 90 | | Yes | 1 | PAD SPACE |
| ucs2_croatian_ci | ucs2 | 149 | | Yes | 8 | PAD SPACE |
| ucs2_czech_ci | ucs2 | 138 | | Yes | 8 | PAD SPACE |
| ucs2_danish_ci | ucs2 | 139 | | Yes | 8 | PAD SPACE |
| ucs2_esperanto_ci | ucs2 | 145 | | Yes | 8 | PAD SPACE |
| ucs2_estonian_ci | ucs2 | 134 | | Yes | 8 | PAD SPACE |
| ucs2_general_ci | ucs2 | 35 | Yes | Yes | 1 | PAD SPACE |
| ucs2_general_mysql500_ci | ucs2 | 159 | | Yes | 1 | PAD SPACE |
| ucs2_german2_ci | ucs2 | 148 | | Yes | 8 | PAD SPACE |
| ucs2_hungarian_ci | ucs2 | 146 | | Yes | 8 | PAD SPACE |
| ucs2_icelandic_ci | ucs2 | 129 | | Yes | 8 | PAD SPACE |
| ucs2_latvian_ci | ucs2 | 130 | | Yes | 8 | PAD SPACE |
| ucs2_lithuanian_ci | ucs2 | 140 | | Yes | 8 | PAD SPACE |
| ucs2_persian_ci | ucs2 | 144 | | Yes | 8 | PAD SPACE |
| ucs2_polish_ci | ucs2 | 133 | | Yes | 8 | PAD SPACE |
| ucs2_romanian_ci | ucs2 | 131 | | Yes | 8 | PAD SPACE |
| ucs2_roman_ci | ucs2 | 143 | | Yes | 8 | PAD SPACE |
| ucs2_sinhala_ci | ucs2 | 147 | | Yes | 8 | PAD SPACE |
| ucs2_slovak_ci | ucs2 | 141 | | Yes | 8 | PAD SPACE |
| ucs2_slovenian_ci | ucs2 | 132 | | Yes | 8 | PAD SPACE |
| ucs2_spanish2_ci | ucs2 | 142 | | Yes | 8 | PAD SPACE |
| ucs2_spanish_ci | ucs2 | 135 | | Yes | 8 | PAD SPACE |
| ucs2_swedish_ci | ucs2 | 136 | | Yes | 8 | PAD SPACE |
| ucs2_turkish_ci | ucs2 | 137 | | Yes | 8 | PAD SPACE |
| ucs2_unicode_520_ci | ucs2 | 150 | | Yes | 8 | PAD SPACE |
| ucs2_unicode_ci | ucs2 | 128 | | Yes | 8 | PAD SPACE |
| ucs2_vietnamese_ci | ucs2 | 151 | | Yes | 8 | PAD SPACE |
| ujis_bin | ujis | 91 | | Yes | 1 | PAD SPACE |
| ujis_japanese_ci | ujis | 12 | Yes | Yes | 1 | PAD SPACE |
| utf16le_bin | utf16le | 62 | | Yes | 1 | PAD SPACE |
| utf16le_general_ci | utf16le | 56 | Yes | Yes | 1 | PAD SPACE |
| utf16_bin | utf16 | 55 | | Yes | 1 | PAD SPACE |
| utf16_croatian_ci | utf16 | 122 | | Yes | 8 | PAD SPACE |
| utf16_czech_ci | utf16 | 111 | | Yes | 8 | PAD SPACE |
| utf16_danish_ci | utf16 | 112 | | Yes | 8 | PAD SPACE |
| utf16_esperanto_ci | utf16 | 118 | | Yes | 8 | PAD SPACE |
| utf16_estonian_ci | utf16 | 107 | | Yes | 8 | PAD SPACE |
| utf16_general_ci | utf16 | 54 | Yes | Yes | 1 | PAD SPACE |
| utf16_german2_ci | utf16 | 121 | | Yes | 8 | PAD SPACE |
| utf16_hungarian_ci | utf16 | 119 | | Yes | 8 | PAD SPACE |
| utf16_icelandic_ci | utf16 | 102 | | Yes | 8 | PAD SPACE |
| utf16_latvian_ci | utf16 | 103 | | Yes | 8 | PAD SPACE |
| utf16_lithuanian_ci | utf16 | 113 | | Yes | 8 | PAD SPACE |
| utf16_persian_ci | utf16 | 117 | | Yes | 8 | PAD SPACE |
| utf16_polish_ci | utf16 | 106 | | Yes | 8 | PAD SPACE |
| utf16_romanian_ci | utf16 | 104 | | Yes | 8 | PAD SPACE |
| utf16_roman_ci | utf16 | 116 | | Yes | 8 | PAD SPACE |
| utf16_sinhala_ci | utf16 | 120 | | Yes | 8 | PAD SPACE |
| utf16_slovak_ci | utf16 | 114 | | Yes | 8 | PAD SPACE |
| utf16_slovenian_ci | utf16 | 105 | | Yes | 8 | PAD SPACE |
| utf16_spanish2_ci | utf16 | 115 | | Yes | 8 | PAD SPACE |
| utf16_spanish_ci | utf16 | 108 | | Yes | 8 | PAD SPACE |
| utf16_swedish_ci | utf16 | 109 | | Yes | 8 | PAD SPACE |
| utf16_turkish_ci | utf16 | 110 | | Yes | 8 | PAD SPACE |
| utf16_unicode_520_ci | utf16 | 123 | | Yes | 8 | PAD SPACE |
| utf16_unicode_ci | utf16 | 101 | | Yes | 8 | PAD SPACE |
| utf16_vietnamese_ci | utf16 | 124 | | Yes | 8 | PAD SPACE |
| utf32_bin | utf32 | 61 | | Yes | 1 | PAD SPACE |
| utf32_croatian_ci | utf32 | 181 | | Yes | 8 | PAD SPACE |
| utf32_czech_ci | utf32 | 170 | | Yes | 8 | PAD SPACE |
| utf32_danish_ci | utf32 | 171 | | Yes | 8 | PAD SPACE |
| utf32_esperanto_ci | utf32 | 177 | | Yes | 8 | PAD SPACE |
| utf32_estonian_ci | utf32 | 166 | | Yes | 8 | PAD SPACE |
| utf32_general_ci | utf32 | 60 | Yes | Yes | 1 | PAD SPACE |
| utf32_german2_ci | utf32 | 180 | | Yes | 8 | PAD SPACE |
| utf32_hungarian_ci | utf32 | 178 | | Yes | 8 | PAD SPACE |
| utf32_icelandic_ci | utf32 | 161 | | Yes | 8 | PAD SPACE |
| utf32_latvian_ci | utf32 | 162 | | Yes | 8 | PAD SPACE |
| utf32_lithuanian_ci | utf32 | 172 | | Yes | 8 | PAD SPACE |
| utf32_persian_ci | utf32 | 176 | | Yes | 8 | PAD SPACE |
| utf32_polish_ci | utf32 | 165 | | Yes | 8 | PAD SPACE |
| utf32_romanian_ci | utf32 | 163 | | Yes | 8 | PAD SPACE |
| utf32_roman_ci | utf32 | 175 | | Yes | 8 | PAD SPACE |
| utf32_sinhala_ci | utf32 | 179 | | Yes | 8 | PAD SPACE |
| utf32_slovak_ci | utf32 | 173 | | Yes | 8 | PAD SPACE |
| utf32_slovenian_ci | utf32 | 164 | | Yes | 8 | PAD SPACE |
| utf32_spanish2_ci | utf32 | 174 | | Yes | 8 | PAD SPACE |
| utf32_spanish_ci | utf32 | 167 | | Yes | 8 | PAD SPACE |
| utf32_swedish_ci | utf32 | 168 | | Yes | 8 | PAD SPACE |
| utf32_turkish_ci | utf32 | 169 | | Yes | 8 | PAD SPACE |
| utf32_unicode_520_ci | utf32 | 182 | | Yes | 8 | PAD SPACE |
| utf32_unicode_ci | utf32 | 160 | | Yes | 8 | PAD SPACE |
| utf32_vietnamese_ci | utf32 | 183 | | Yes | 8 | PAD SPACE |
| utf8mb4_0900_ai_ci | utf8mb4 | 255 | Yes | Yes | 0 | NO PAD |
| utf8mb4_0900_as_ci | utf8mb4 | 305 | | Yes | 0 | NO PAD |
| utf8mb4_0900_as_cs | utf8mb4 | 278 | | Yes | 0 | NO PAD |
| utf8mb4_0900_bin | utf8mb4 | 309 | | Yes | 1 | NO PAD |
| utf8mb4_bin | utf8mb4 | 46 | | Yes | 1 | PAD SPACE |
| utf8mb4_croatian_ci | utf8mb4 | 245 | | Yes | 8 | PAD SPACE |
| utf8mb4_cs_0900_ai_ci | utf8mb4 | 266 | | Yes | 0 | NO PAD |
| utf8mb4_cs_0900_as_cs | utf8mb4 | 289 | | Yes | 0 | NO PAD |
| utf8mb4_czech_ci | utf8mb4 | 234 | | Yes | 8 | PAD SPACE |
| utf8mb4_danish_ci | utf8mb4 | 235 | | Yes | 8 | PAD SPACE |
| utf8mb4_da_0900_ai_ci | utf8mb4 | 267 | | Yes | 0 | NO PAD |
| utf8mb4_da_0900_as_cs | utf8mb4 | 290 | | Yes | 0 | NO PAD |
| utf8mb4_de_pb_0900_ai_ci | utf8mb4 | 256 | | Yes | 0 | NO PAD |
| utf8mb4_de_pb_0900_as_cs | utf8mb4 | 279 | | Yes | 0 | NO PAD |
| utf8mb4_eo_0900_ai_ci | utf8mb4 | 273 | | Yes | 0 | NO PAD |
| utf8mb4_eo_0900_as_cs | utf8mb4 | 296 | | Yes | 0 | NO PAD |
| utf8mb4_esperanto_ci | utf8mb4 | 241 | | Yes | 8 | PAD SPACE |
| utf8mb4_estonian_ci | utf8mb4 | 230 | | Yes | 8 | PAD SPACE |
| utf8mb4_es_0900_ai_ci | utf8mb4 | 263 | | Yes | 0 | NO PAD |
| utf8mb4_es_0900_as_cs | utf8mb4 | 286 | | Yes | 0 | NO PAD |
| utf8mb4_es_trad_0900_ai_ci | utf8mb4 | 270 | | Yes | 0 | NO PAD |
| utf8mb4_es_trad_0900_as_cs | utf8mb4 | 293 | | Yes | 0 | NO PAD |
| utf8mb4_et_0900_ai_ci | utf8mb4 | 262 | | Yes | 0 | NO PAD |
| utf8mb4_et_0900_as_cs | utf8mb4 | 285 | | Yes | 0 | NO PAD |
| utf8mb4_general_ci | utf8mb4 | 45 | | Yes | 1 | PAD SPACE |
| utf8mb4_german2_ci | utf8mb4 | 244 | | Yes | 8 | PAD SPACE |
| utf8mb4_hr_0900_ai_ci | utf8mb4 | 275 | | Yes | 0 | NO PAD |
| utf8mb4_hr_0900_as_cs | utf8mb4 | 298 | | Yes | 0 | NO PAD |
| utf8mb4_hungarian_ci | utf8mb4 | 242 | | Yes | 8 | PAD SPACE |
| utf8mb4_hu_0900_ai_ci | utf8mb4 | 274 | | Yes | 0 | NO PAD |
| utf8mb4_hu_0900_as_cs | utf8mb4 | 297 | | Yes | 0 | NO PAD |
| utf8mb4_icelandic_ci | utf8mb4 | 225 | | Yes | 8 | PAD SPACE |
| utf8mb4_is_0900_ai_ci | utf8mb4 | 257 | | Yes | 0 | NO PAD |
| utf8mb4_is_0900_as_cs | utf8mb4 | 280 | | Yes | 0 | NO PAD |
| utf8mb4_ja_0900_as_cs | utf8mb4 | 303 | | Yes | 0 | NO PAD |
| utf8mb4_ja_0900_as_cs_ks | utf8mb4 | 304 | | Yes | 24 | NO PAD |
| utf8mb4_latvian_ci | utf8mb4 | 226 | | Yes | 8 | PAD SPACE |
| utf8mb4_la_0900_ai_ci | utf8mb4 | 271 | | Yes | 0 | NO PAD |
| utf8mb4_la_0900_as_cs | utf8mb4 | 294 | | Yes | 0 | NO PAD |
| utf8mb4_lithuanian_ci | utf8mb4 | 236 | | Yes | 8 | PAD SPACE |
| utf8mb4_lt_0900_ai_ci | utf8mb4 | 268 | | Yes | 0 | NO PAD |
| utf8mb4_lt_0900_as_cs | utf8mb4 | 291 | | Yes | 0 | NO PAD |
| utf8mb4_lv_0900_ai_ci | utf8mb4 | 258 | | Yes | 0 | NO PAD |
| utf8mb4_lv_0900_as_cs | utf8mb4 | 281 | | Yes | 0 | NO PAD |
| utf8mb4_persian_ci | utf8mb4 | 240 | | Yes | 8 | PAD SPACE |
| utf8mb4_pl_0900_ai_ci | utf8mb4 | 261 | | Yes | 0 | NO PAD |
| utf8mb4_pl_0900_as_cs | utf8mb4 | 284 | | Yes | 0 | NO PAD |
| utf8mb4_polish_ci | utf8mb4 | 229 | | Yes | 8 | PAD SPACE |
| utf8mb4_romanian_ci | utf8mb4 | 227 | | Yes | 8 | PAD SPACE |
| utf8mb4_roman_ci | utf8mb4 | 239 | | Yes | 8 | PAD SPACE |
| utf8mb4_ro_0900_ai_ci | utf8mb4 | 259 | | Yes | 0 | NO PAD |
| utf8mb4_ro_0900_as_cs | utf8mb4 | 282 | | Yes | 0 | NO PAD |
| utf8mb4_ru_0900_ai_ci | utf8mb4 | 306 | | Yes | 0 | NO PAD |
| utf8mb4_ru_0900_as_cs | utf8mb4 | 307 | | Yes | 0 | NO PAD |
| utf8mb4_sinhala_ci | utf8mb4 | 243 | | Yes | 8 | PAD SPACE |
| utf8mb4_sk_0900_ai_ci | utf8mb4 | 269 | | Yes | 0 | NO PAD |
| utf8mb4_sk_0900_as_cs | utf8mb4 | 292 | | Yes | 0 | NO PAD |
| utf8mb4_slovak_ci | utf8mb4 | 237 | | Yes | 8 | PAD SPACE |
| utf8mb4_slovenian_ci | utf8mb4 | 228 | | Yes | 8 | PAD SPACE |
| utf8mb4_sl_0900_ai_ci | utf8mb4 | 260 | | Yes | 0 | NO PAD |
| utf8mb4_sl_0900_as_cs | utf8mb4 | 283 | | Yes | 0 | NO PAD |
| utf8mb4_spanish2_ci | utf8mb4 | 238 | | Yes | 8 | PAD SPACE |
| utf8mb4_spanish_ci | utf8mb4 | 231 | | Yes | 8 | PAD SPACE |
| utf8mb4_sv_0900_ai_ci | utf8mb4 | 264 | | Yes | 0 | NO PAD |
| utf8mb4_sv_0900_as_cs | utf8mb4 | 287 | | Yes | 0 | NO PAD |
| utf8mb4_swedish_ci | utf8mb4 | 232 | | Yes | 8 | PAD SPACE |
| utf8mb4_tr_0900_ai_ci | utf8mb4 | 265 | | Yes | 0 | NO PAD |
| utf8mb4_tr_0900_as_cs | utf8mb4 | 288 | | Yes | 0 | NO PAD |
| utf8mb4_turkish_ci | utf8mb4 | 233 | | Yes | 8 | PAD SPACE |
| utf8mb4_unicode_520_ci | utf8mb4 | 246 | | Yes | 8 | PAD SPACE |
| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 8 | PAD SPACE |
| utf8mb4_vietnamese_ci | utf8mb4 | 247 | | Yes | 8 | PAD SPACE |
| utf8mb4_vi_0900_ai_ci | utf8mb4 | 277 | | Yes | 0 | NO PAD |
| utf8mb4_vi_0900_as_cs | utf8mb4 | 300 | | Yes | 0 | NO PAD |
| utf8mb4_zh_0900_as_cs | utf8mb4 | 308 | | Yes | 0 | NO PAD |
| utf8_bin | utf8 | 83 | | Yes | 1 | PAD SPACE |
| utf8_croatian_ci | utf8 | 213 | | Yes | 8 | PAD SPACE |
| utf8_czech_ci | utf8 | 202 | | Yes | 8 | PAD SPACE |
| utf8_danish_ci | utf8 | 203 | | Yes | 8 | PAD SPACE |
| utf8_esperanto_ci | utf8 | 209 | | Yes | 8 | PAD SPACE |
| utf8_estonian_ci | utf8 | 198 | | Yes | 8 | PAD SPACE |
| utf8_general_ci | utf8 | 33 | Yes | Yes | 1 | PAD SPACE |
| utf8_general_mysql500_ci | utf8 | 223 | | Yes | 1 | PAD SPACE |
| utf8_german2_ci | utf8 | 212 | | Yes | 8 | PAD SPACE |
| utf8_hungarian_ci | utf8 | 210 | | Yes | 8 | PAD SPACE |
| utf8_icelandic_ci | utf8 | 193 | | Yes | 8 | PAD SPACE |
| utf8_latvian_ci | utf8 | 194 | | Yes | 8 | PAD SPACE |
| utf8_lithuanian_ci | utf8 | 204 | | Yes | 8 | PAD SPACE |
| utf8_persian_ci | utf8 | 208 | | Yes | 8 | PAD SPACE |
| utf8_polish_ci | utf8 | 197 | | Yes | 8 | PAD SPACE |
| utf8_romanian_ci | utf8 | 195 | | Yes | 8 | PAD SPACE |
| utf8_roman_ci | utf8 | 207 | | Yes | 8 | PAD SPACE |
| utf8_sinhala_ci | utf8 | 211 | | Yes | 8 | PAD SPACE |
| utf8_slovak_ci | utf8 | 205 | | Yes | 8 | PAD SPACE |
| utf8_slovenian_ci | utf8 | 196 | | Yes | 8 | PAD SPACE |
| utf8_spanish2_ci | utf8 | 206 | | Yes | 8 | PAD SPACE |
| utf8_spanish_ci | utf8 | 199 | | Yes | 8 | PAD SPACE |
| utf8_swedish_ci | utf8 | 200 | | Yes | 8 | PAD SPACE |
| utf8_tolower_ci | utf8 | 76 | | Yes | 1 | PAD SPACE |
| utf8_turkish_ci | utf8 | 201 | | Yes | 8 | PAD SPACE |
| utf8_unicode_520_ci | utf8 | 214 | | Yes | 8 | PAD SPACE |
| utf8_unicode_ci | utf8 | 192 | | Yes | 8 | PAD SPACE |
| utf8_vietnamese_ci | utf8 | 215 | | Yes | 8 | PAD SPACE |
+----------------------------+----------+-----+---------+----------+---------+---------------+
272 rows in set (0.03 sec)查看服务器当前字符集和排序规则
可以使用 show variables like '%character%' 和 show variables like '%collation%' 查看
character_set_client 表示客户端使用的字符集
character_set_connection 表示连接层字符集
character_set_results 表示查询结果字符集
character_set_server 表示服务器字符集
mysql> show variables like '%character%';
+--------------------------+--------------------------------+
| Variable_name | Value |
+--------------------------+--------------------------------+
| character_set_client | utf8mb4 || character_set_connection | utf8mb4 |
| character_set_database | utf8mb4 || character_set_filesystem | binary |
| character_set_results | utf8mb4 || character_set_server | utf8mb4 |
| character_set_system | utf8 || character_sets_dir | /usr/share/mysql-8.0/charsets/ |
+--------------------------+--------------------------------+
8 rows in set (0.01 sec)
mysql> show variables like '%collation%';
+-------------------------------+--------------------+
| Variable_name | Value |
+-------------------------------+--------------------+
| collation_connection | utf8mb4_0900_ai_ci |
| collation_database | utf8mb4_0900_ai_ci || collation_server | utf8mb4_0900_ai_ci |
| default_collation_for_utf8mb4 | utf8mb4_0900_ai_ci |
+-------------------------------+--------------------+
4 rows in set (0.01 sec)查看数据库， 表，字段的字符集
mysql> use TEST;
Database changed
mysql> show variables like 'character_set_database';
+------------------------+---------+
| Variable_name | Value |
+------------------------+---------+
| character_set_database | utf8mb4 |
+------------------------+---------+
1 row in set (0.01 sec)
mysql> show table status from TEST like 'T1';
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-------------+----------+----------------+---------+
| Name | Engine | Version | Row_format | Rows | Avg_row_length | Data_length | Max_data_length | Index_length | Data_free | Auto_increment | Create_time | Update_time | Check_time | Collation | Checksum | Create_options | Comment |
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-------------+----------+----------------+---------+
| T1 | InnoDB |10| Dynamic |0| 0 |16384| 0 |0| 0 | NULL | 2023-03-22 09:10:17 | NULL | NULL | utf8mb4_bin | NULL || |
+------+--------+---------+------------+------+----------------+-------------+-----------------+--------------+-----------+----------------+---------------------+-------------+------------+-------------+----------+----------------+---------+
1 row in set (0.01 sec)
mysql> show full columns from TEST.T1;
+-------+--------------+-------------+------+-----+---------+-------+---------------------------------+---------+
| Field | Type | Collation | Null | Key | Default | Extra | Privileges | Comment |
+-------+--------------+-------------+------+-----+---------+-------+---------------------------------+---------+
| C1 | varchar(255) | utf8mb4_bin | YES | | NULL | | select,insert,update,references | |
+-------+--------------+-------------+------+-----+---------+-------+---------------------------------+---------+
1 row in set (0.01 sec)本文章为转载内容，我们尊重原作者对文章享有的著作权。如有内容错误或侵权问题，欢迎原作者联系我们进行内容更正或删除文章。
