blocks|key|2915249|text|UTF-8是一种可变长度编码。在使用UTF-8的情况下，这意味着存储一个码点需要一到四个字节。然而，MySQL的名为"utf8“(别名为"utf8mb3")的编码，每个代码点最多只能存储三个字节。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2915250|因此字符集"utf8"/"utf8mb3“不能存储所有的Unicode代码点:它只支持从0x000到0xFFFF的范围，也就是所谓的"Basic+Multilingual+Plane”。另请参见Comparison+of+Unicode+encodings。|2915251|这是(上一个版本的同一页面)+the+MySQL+documentation对此的评论：|2915252|2915253|名为utf8/utf8mb3的字符集每个字符最多使用三个字节，并且仅包含BMP字符。从MySQL+5.5.3开始，utf8mb4字符集每个字符最多使用四个字节，支持补充字符：|blockquote|2915254|2915255|2915256|2915257|对于BMP字符，utf8/utf8mb3和utf8mb4具有相同的存储特征:相同的代码值、相同的编码、相同的长度。|unordered-list-item|2915258|2915259|2915260|对于补充字符，utf8/utf8mb3根本不能存储该字符，而utf8mb4需要四个字节来存储它。由于utf8/utf8mb3根本不能存储字符，因此utf8/utf8mb3列中没有任何补充字符，因此在从旧版本的MySQL升级utf8/utf8mb3数据时，无需担心转换字符或丢失数据。|style|BOLD|2915261|2915262|因此，如果您希望列支持存储位于BMP之外的字符(而且您通常希望这样做)，比如emoji，那么可以使用"utf8mb4“。另请参见What+are+the+most+common+non-BMP+Unicode+characters+in+actual+use?。|2915263|entityMap|0|LINK|mutability|MUTABLE|url|https://en.wikipedia.org/wiki/UTF-8|1|http://en.wikipedia.org/wiki/Plane_%2528Unicode%2529#Basic_Multilingual_Plane|2|http://en.wikipedia.org/wiki/Comparison_of_Unicode_encodings#In_detail|3|https://dev.mysql.com/doc/refman/5.5/en/charset-unicode-utf8mb4.html|4|https://en.wikipedia.org/wiki/Emoji|5|https://stackoverflow.com/questions/5567249/what-are-the-most-common-non-bmp-unicode-characters-in-actual-use^0|0|5|0|0|1V|O|1|2P|V|2|0|F|N|3|0|0|0|0|0|0|0|0|0|7|3Q|0|0|0|3N|12|5|4|1S|1U|5|0^^$0|@$1|2|3|4|5|6|7|1I|8|@]|9|@$A|1J|B|1K|1|1L]]|C|$]]|$1|D|3|E|5|6|7|1M|8|@]|9|@$A|1N|B|1O|1|1P]|$A|1Q|B|1R|1|1S]]|C|$]]|$1|F|3|G|5|6|7|1T|8|@]|9|@$A|1U|B|1V|1|1W]]|C|$]]|$1|H|3|-4|5|6|7|1X|8|@]|9|@]|C|$]]|$1|I|3|J|5|K|7|1Y|8|@]|9|@]|C|$]]|$1|L|3|-4|5|6|7|1Z|8|@]|9|@]|C|$]]|$1|M|3|-4|5|6|7|20|8|@]|9|@]|C|$]]|$1|N|3|-4|5|6|7|21|8|@]|9|@]|C|$]]|$1|O|3|P|5|Q|7|22|8|@]|9|@]|C|$]]|$1|R|3|-4|5|6|7|23|8|@]|9|@]|C|$]]|$1|S|3|-4|5|6|7|24|8|@]|9|@]|C|$]]|$1|T|3|U|5|Q|7|25|8|@$A|26|B|27|V|W]]|9|@]|C|$]]|$1|X|3|-4|5|6|7|28|8|@]|9|@]|C|$]]|$1|Y|3|Z|5|6|7|29|8|@$A|2A|B|2B|V|W]]|9|@$A|2C|B|2D|1|2E]|$A|2F|B|2G|1|2H]]|C|$]]|$1|10|3|-4|5|6|7|2I|8|@]|9|@]|C|$]]]|11|$12|$5|13|14|15|C|$16|17]]|18|$5|13|14|15|C|$16|19]]|1A|$5|13|14|15|C|$16|1B]]|1C|$5|13|14|15|C|$16|1D]]|1E|$5|13|14|15|C|$16|1F]]|1G|$5|13|14|15|C|$16|1H]]]]

<a href="https://en.wikipedia.org/wiki/UTF-8" rel="noreferrer">UTF-8</a> is a variable-length encoding. In the case of UTF-8, this means that storing one code point requires one to four bytes. However, MySQL's encoding called &quot;utf8&quot; (alias of &quot;utf8mb3&quot;) only stores a maximum of three bytes per code point.
So the character set &quot;utf8&quot;/&quot;utf8mb3&quot; cannot store all Unicode code points: it only supports the range 0x000 to 0xFFFF, which is called the &quot;<a href="http://en.wikipedia.org/wiki/Plane_%28Unicode%29#Basic_Multilingual_Plane" rel="noreferrer">Basic Multilingual Plane</a>&quot;.
See also <a href="http://en.wikipedia.org/wiki/Comparison_of_Unicode_encodings#In_detail" rel="noreferrer">Comparison of Unicode encodings</a>.
This is what (a previous version of the same page at) <a href="https://dev.mysql.com/doc/refman/5.5/en/charset-unicode-utf8mb4.html" rel="noreferrer">the MySQL documentation</a> has to say about it:
<blockquote>
The character set named utf8[/utf8mb3] uses a maximum of three bytes per character and contains only BMP characters. As of MySQL 5.5.3, the utf8mb4 character set uses a maximum of four bytes per character supports supplemental characters:
<ul>
<li>For a BMP character, utf8[/utf8mb3] and utf8mb4 have identical storage characteristics: same code values, same encoding, same length.
</li>
<li>For a supplementary character, utf8[/utf8mb3] cannot store the character at all, while utf8mb4 requires four bytes to store it. Since utf8[/utf8mb3] cannot store the character at all, you do not have any supplementary characters in utf8[/utf8mb3] columns and you need not worry about converting characters or losing data when upgrading utf8[/utf8mb3] data from older versions of MySQL.
</li>
</ul>
</blockquote>
So if you want your column to support storing characters lying outside the BMP (and you usually want to), such as <a href="https://en.wikipedia.org/wiki/Emoji" rel="noreferrer">emoji</a>, use &quot;utf8mb4&quot;. See also <a href="https://stackoverflow.com/questions/5567249/what-are-the-most-common-non-bmp-unicode-characters-in-actual-use">What are the most common non-BMP Unicode characters in actual use?</a>.

blocks|key|2702755|text|utf8mb4字符集非常有用，因为现在我们不仅需要支持存储语言字符，还需要支持存储符号、新引入的表情符号等。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2702756|马蒂亚斯·拜恩斯在How+to+support+full+Unicode+in+MySQL+databases上的一篇不错的读物也可以说明这一点。|2702757|entityMap|0|LINK|mutability|MUTABLE|url|https://mathiasbynens.be/notes/mysql-utf8mb4^0|0|7|0|9|1A|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@]|D|@$9|T|A|U|1|V]]|E|$]]|$1|H|3|-4|5|6|7|W|8|@]|D|@]|E|$]]]|I|$J|$5|K|L|M|E|$N|O]]]]

The <code>utf8mb4</code> character set is useful because nowadays we need support for storing not only language characters but also symbols, newly introduced emojis, and so on.

A nice read on <a href="https://mathiasbynens.be/notes/mysql-utf8mb4" rel="noreferrer">How to support full Unicode in MySQL databases</a> by Mathias Bynens can also shed some light on this.

blocks|key|2702781|text|摘自MySQL+8.0+Reference+Manual|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2702782|2702783|blockquote|2702784|2702785|2702786|utf8mb4：使用对Unicode字符集进行UTF-8编码每个character.|unordered-list-item|style|CODE|BOLD|2702787|utf8mb3：使用一到四个字节使用对Unicode字符集进行UTF-8编码每个字符使用一到三个字节。|2702788|2702789|在MySQL中，utf8目前是utf8mb3的别名，已被弃用，并将在未来的MySQL版本中删除。在这一点上，utf8+将成为+utf8mb4的引用。|2702790|因此，不管别名是什么，您都可以有意识地为自己设置一个utf8mb4编码。|2702791|为了完整地回答这个问题，我想在下面添加+@WilliamEntriken's+注释(也取自手册)：|2702792|2702793|若要避免对utf8含义的歧义，请考虑为字符集引用显式指定utf8mb4，而不是utf8。|2702794|2702795|entityMap|0|LINK|mutability|MUTABLE|url|https://dev.mysql.com/doc/refman/8.0/en/charset-unicode-sets.html^0|2|Q|0|0|0|0|0|0|0|7|A|W|0|0|G|I|W|0|7|0|0|8|4|F|7|1I|4|1R|7|Q|2|1N|3|0|Q|7|0|K|I|13|A|0|0|0|18|5|4|S|7|13|4|0|0^^$0|@$1|2|3|4|5|6|7|19|8|@]|9|@$A|1A|B|1B|1|1C]]|C|$]]|$1|D|3|-4|5|6|7|1D|8|@]|9|@]|C|$]]|$1|E|3|-4|5|F|7|1E|8|@]|9|@]|C|$]]|$1|G|3|-4|5|6|7|1F|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|1G|8|@]|9|@]|C|$]]|$1|I|3|J|5|K|7|1H|8|@$A|1I|B|1J|L|M]|$A|1K|B|1L|L|N]]|9|@]|C|$]]|$1|O|3|P|5|K|7|1M|8|@$A|1N|B|1O|L|N]|$A|1P|B|1Q|L|N]|$A|1R|B|1S|L|M]]|9|@]|C|$]]|$1|Q|3|-4|5|6|7|1T|8|@]|9|@]|C|$]]|$1|R|3|S|5|6|7|1U|8|@$A|1V|B|1W|L|M]|$A|1X|B|1Y|L|M]|$A|1Z|B|20|L|M]|$A|21|B|22|L|M]|$A|23|B|24|L|N]|$A|25|B|26|L|N]]|9|@]|C|$]]|$1|T|3|U|5|6|7|27|8|@$A|28|B|29|L|M]]|9|@]|C|$]]|$1|V|3|W|5|6|7|2A|8|@$A|2B|B|2C|L|N]|$A|2D|B|2E|L|N]]|9|@]|C|$]]|$1|X|3|-4|5|6|7|2F|8|@]|9|@]|C|$]]|$1|Y|3|Z|5|F|7|2G|8|@$A|2H|B|2I|L|N]|$A|2J|B|2K|L|M]|$A|2L|B|2M|L|M]|$A|2N|B|2O|L|M]]|9|@]|C|$]]|$1|10|3|-4|5|6|7|2P|8|@]|9|@]|C|$]]|$1|11|3|-4|5|6|7|2Q|8|@]|9|@]|C|$]]]|12|$13|$5|14|15|16|C|$17|18]]]]

Taken from the <a href="https://dev.mysql.com/doc/refman/8.0/en/charset-unicode-sets.html" rel="noreferrer">MySQL 8.0 Reference Manual</a>:

<blockquote>
 <ul>
 <li><code>utf8mb4</code>: A UTF-8 encoding of the Unicode character set using one to
 four bytes per character.</li>
 <li><code>utf8mb3</code>: A UTF-8 encoding of the Unicode character set using one to
 three bytes per character.</li>
 </ul>
</blockquote>

In MySQL <code>utf8</code> is currently an alias for <code>utf8mb3</code> which is deprecated and will be removed in a future MySQL release. At that point <code>utf8</code> will become a reference to <code>utf8mb4</code>.

So regardless of this alias, you can consciously set yourself an <code>utf8mb4</code> encoding.

To complete the answer, I'd like to add the @WilliamEntriken's comment below (also taken from the manual):

<blockquote>
 To avoid ambiguity about the meaning of <code>utf8</code>, consider specifying <code>utf8mb4</code> explicitly for character set references instead of <code>utf8</code>.
</blockquote>

blocks|key|137146|text|MySQL在5.5.3之后添加了这段utf8mb4代码，Mb4是最多字节4的意思，专门设计来兼容四个字节的Unicode。幸运的是，除了不需要将编码转换为UTF8MB4之外，UTF8MB4是UTF8的超集。当然，为了节省空间，一般使用UTF8就足够了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|137147|原始的UTF-8格式使用1到6个字节，最多可以编码31个字符。最新的UTF-8规范仅使用一到四个字节，最多可编码21位，仅表示所有17个Unicode平面。UTF8是Mysql中的一个字符集，它只支持最多三个字节的UTF-8字符，这是Unicode中的基本多文本平面。|137148|要在Mysql中保存4字节长的UTF-8字符，您需要使用UTF8MB4字符集，但只需使用5.5。支持3个版本后(查看版本:选择版本();)。我认为为了获得更好的兼容性，你应该总是使用UTF8MB4而不是UTF8。对于char类型的数据，UTF8MB4会消耗更多的空间，并且根据Mysql的官方推荐，使用VARCHAR而不是char。|137149|在未在服务器配置中显式设置的情况下，在MariaDB+utf8mb4中将其设置为默认字符集，因此使用COLLATE+utf8mb4_unicode_ci。|137150|Refer+MariaDB+CHARSET+&+COLLATE+Click|offset|length|137151|CHARSET=utf8mb4+COLLATE=utf8mb4_unicode_ci;|code-block|syntax|javascript|137152|entityMap|0|LINK|mutability|MUTABLE|url|https://mariadb.com/kb/en/supported-character-sets-and-collations/^0|0|0|0|0|0|11|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|10|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|11|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|12|8|@]|9|@$J|13|K|14|1|15]]|A|$]]|$1|L|3|M|5|N|7|16|8|@]|9|@]|A|$O|P]]|$1|Q|3|-4|5|6|7|17|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

MySQL added this utf8mb4 code after 5.5.3, Mb4 is the most bytes 4 meaning, specifically designed to be compatible with four-byte Unicode. Fortunately, UTF8MB4 is a superset of UTF8, except that there is no need to convert the encoding to UTF8MB4. Of course, in order to save space, the general use of UTF8 is enough.
The original UTF-8 format uses one to six bytes and can encode 31 characters maximum. The latest UTF-8 specification uses only one to four bytes and can encode up to 21 bits, just to represent all 17 Unicode planes. UTF8 is a character set in Mysql that supports only a maximum of three bytes of UTF-8 characters, which is the basic multi-text plane in Unicode.
To save 4-byte-long UTF-8 characters in Mysql, you need to use the UTF8MB4 character set, but only 5.5. After 3 versions are supported (View version: Select version ();). I think that in order to get better compatibility, you should always use UTF8MB4 instead of UTF8. For char type data, UTF8MB4 consumes more space and, according to Mysql's official recommendation, uses VARCHAR instead of char.
In MariaDB utf8mb4 as the default CHARSET when it not set explicitly in the server config, hence COLLATE utf8mb4_unicode_ci is used.
<a href="https://mariadb.com/kb/en/supported-character-sets-and-collations/" rel="nofollow noreferrer">Refer MariaDB CHARSET &amp; COLLATE Click</a>
<pre><code>CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
</code></pre>

blocks|key|2702963|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2702964|utf8是MySQL的旧的，有缺陷的UTF-8实现，它正在被deprecated.|unordered-list-item|offset|length|style|CODE|2702965|utf8mb4的过程中，这是他们固定的UTF-8实现的名字，也是你现在应该使用的。|2702966|2702967|在他们有缺陷的版本中，只有前64k字符平面-基本的多语言平面-中的字符有效，其他字符被认为是无效的。该平面内的码位值-0到65535+(其中一些是为特殊原因保留的)可以用最多3字节的UTF-8多字节编码来表示，MySQL的早期版本的UTF-8随意决定将其设置为限制。这一限制从来不是对UTF-8规则的正确解释，因为UTF-8没有被定义为每个字符最多允许3个字节。事实上，UTF-8的最早定义将其定义为最多具有6个字节(后来修改为4个字节)。MySQL的原始版本总是被任意残缺。|2702968|回到MySQL发布这个版本的时候，这个限制的后果并不是太糟糕，因为大多数Unicode字符都在第一个平面上。从那时起，越来越多新定义字符范围被添加到Unicode中，其值位于第一个平面之外。Unicode本身定义了17个平面，尽管到目前为止只使用了其中的7个平面。|2702969|为了不破坏旧代码做出任何特定的假设，MySQL保留了被破坏的实现，并将其称为更新的、已修复的版本utf8mb4。这导致了一些混淆，因为名称被误解为UTF-8的某种扩展或UTF-8的替代形式，而不是MySQL对真正的UTF-8的实现。|2702970|MySQL的未来版本最终将逐步淘汰旧版本，目前可以认为它已被弃用。在可预见的将来，您需要使用utf8mb4来确保正确的UTF8编码。经过足够的时间后，当前的utf8将被删除，并且在未来的某个日期，utf8将再次上升，这一次指的是固定版本，尽管utf8mb4将继续明确地指的是固定版本。|2702971|entityMap^0|0|0|4|0|0|7|0|0|0|0|1C|7|0|1A|7|26|4|2Q|4|3D|7|0^^$0|@$1|2|3|-4|4|5|6|U|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|V|7|@$D|W|E|X|F|G]]|8|@]|9|$]]|$1|H|3|I|4|C|6|Y|7|@$D|Z|E|10|F|G]]|8|@]|9|$]]|$1|J|3|-4|4|5|6|11|7|@]|8|@]|9|$]]|$1|K|3|L|4|5|6|12|7|@]|8|@]|9|$]]|$1|M|3|N|4|5|6|13|7|@]|8|@]|9|$]]|$1|O|3|P|4|5|6|14|7|@$D|15|E|16|F|G]]|8|@]|9|$]]|$1|Q|3|R|4|5|6|17|7|@$D|18|E|19|F|G]|$D|1A|E|1B|F|G]|$D|1C|E|1D|F|G]|$D|1E|E|1F|F|G]]|8|@]|9|$]]|$1|S|3|-4|4|5|6|1G|7|@]|8|@]|9|$]]]|T|$]]

<ul>
<li><code>utf8</code> is MySQL's older, flawed implementation of UTF-8 which is in the process of being deprecated.</li>
<li><code>utf8mb4</code> is what they named their fixed UTF-8 implementation, and is what you should use right now.</li>
</ul>
In their flawed version, only characters in the first 64k character plane - the basic multilingual plane - work, with other characters considered invalid. The code point values within that plane - 0 to 65535 (some of which are reserved for special reasons) can be represented by multi-byte encodings in UTF-8 of up to 3 bytes, and MySQL's early version of UTF-8 arbitrarily decided to set that as a limit. At no point was this limitation a correct interpretation of the UTF-8 rules, because at no point was UTF-8 defined as only allowing up to 3 bytes per character. In fact, the earliest definitions of UTF-8 defined it as having up to 6 bytes (since revised to 4). MySQL's original version was always arbitrarily crippled.
Back when MySQL released this, the consequences of this limitation weren't too bad as most Unicode characters were in that first plane. Since then, more and more newly defined character ranges have been added to Unicode with values outside that first plane. Unicode itself defines 17 planes, though so far only 7 of these are used.
In an effort not to break old code making any particular assumptions, MySQL retained the broken implementation and called the newer, fixed version <code>utf8mb4</code>. This has led to some confusion with the name being misinterpreted as if it's some kind of extension to UTF-8 or alternative form of UTF-8, rather than MySQL's implementation of the true UTF-8.
Future versions of MySQL will eventually phase out the older version, and for now it can be considered deprecated. For the foreseeable future you need to use <code>utf8mb4</code> to ensure correct UTF-8 encoding. After sufficient time has passed, the current <code>utf8</code> will be removed, and at some future date <code>utf8</code> will rise again, this time referring to the fixed version, though <code>utf8mb4</code> will continue to unambiguously refer to the fixed version.

What is the difference between <code>utf8mb4</code> and <code>utf8</code> charsets in MySQL?

I already know about ASCII, UTF-8, UTF-16 and UTF-32 encodings;
but I'm curious to know whats the difference of <code>utf8mb4</code> group of encodings with other encoding types defined in MySQL Server.

Are there any special benefits/proposes of using <code>utf8mb4</code> rather than <code>utf8</code>?

What is the difference between utf8mb4 and utf8 charsets in MySQL?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

教程

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云智能顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

EdgeOne AI 安全实战专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

聚焦“写作效率、视觉美观与运行性能”三方面进行全面升级，为您提供更高效、稳定的创作环境

社区富文本&Markdown编辑器全新改版上线，欢迎大家体验!

诚挚邀请您参与本次调研，分享您的真实使用感受与建议。您的反馈至关重要，感谢您的支持与参与！

社区新版编辑器体验调研

在MySQL中，utf8mb4和utf8字符集有什么不同我已经知道了ASCII 8，UTF-16和UTF-32编码；但是我很好奇utf8mb4编码组与MySQL服务器中定义的其他编码类型有什么不同。使用 utf8**?**而不是有什么特别的好处/建议

问utf8mb4和MySQL中的utf8字符集有什么区别？
EN

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问utf8mb4和MySQL中的utf8字符集有什么区别？EN