blocks|key|208622|text|基本上，nvarchar意味着你可以处理很多字母表，而不仅仅是普通的英语。从技术上讲，这意味着支持unicode，而不仅仅是ANSI。这意味着两倍宽的字符或大约两倍的空格。如今，磁盘空间非常便宜，您可以从一开始就使用nvarchar，而不是经历在产品生命周期中必须进行更改的痛苦。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|208623|如果你确定你只需要支持一种语言，你可以坚持使用varchar，否则我会选择nvarchar。|208624|这在here之前就已经在SO上讨论过了。|offset|length|208625|编辑:按照注释中的说明，将ascii更改为ANSI。|208626|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/35366/varchar-vs-nvarchar-performance^0|0|0|2|4|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|S|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|T|8|@]|9|@$F|U|G|V|1|W]]|A|$]]|$1|H|3|I|5|6|7|X|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|Y|8|@]|9|@]|A|$]]]|K|$L|$5|M|N|O|A|$P|Q]]]]

Basically, nvarchar means you can handle lots of alphabets, not just regular English. Technically, it means unicode support, not just ANSI. This means double-width characters or approximately twice the space. These days disk space is so cheap you might as well use nvarchar from the beginning rather than go through the pain of having to change during the life of a product.

If you're certain you'll only ever need to support one language you could stick with varchar, otherwise I'd go with nvarchar.

This has been discussed on SO before <a href="https://stackoverflow.com/questions/35366/varchar-vs-nvarchar-performance">here</a>.

EDITED: changed ascii to ANSI as noted in comment.

blocks|key|4506325|text|首先，为了澄清，nvarchar存储unicode数据，而varchar存储ANSI+(8位)数据。它们的功能相同，但nvarchar占用了两倍的空间。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4506326|通常，我更喜欢使用varchar数据类型存储用户名，除非这些名称的字符超出了varchar可以存储的字符边界。|4506327|它还依赖于数据库排序规则。例如，如果您的数据库排序规则为LATIN_CS_AS，您将无法在varchar字段中存储俄语字符。但是，如果您使用的是本地应用程序，则应将数据库排序规则设置为俄语。这将允许您在varchar字段中输入俄语字符，从而节省一些空间。|4506328|但是，现在，大多数正在开发的应用程序都是国际化的，所以您必须自己决定哪些用户将注册，并根据这些决定数据类型。|4506329|entityMap^0|8|8|T|7|0|9|7|12|7|0|S|B|19|7|2T|7|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|S|8|@$9|T|A|U|B|C]|$9|V|A|W|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|X|8|@$9|Y|A|Z|B|C]|$9|10|A|11|B|C]|$9|12|A|13|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|14|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|M|$]]

First of all, to clarify, <code>nvarchar</code> stores unicode data while <code>varchar</code> stores ANSI (8-bit) data. They function identically but nvarchar takes up twice as much space.

Generally, I prefer storing user names using <code>varchar</code> datatypes unless those names have characters which fall out of the boundary of characters which <code>varchar</code> can store.

It also depends on database collation also. For e.g. you'll not be able to store Russian characters in a <code>varchar</code> field, if your database collation is <code>LATIN_CS_AS</code>. But, if you are working on a local application, which will be used only in Russia, you'd set the database collation to Russian. What this will do is that it will allow you to enter Russian characters in a <code>varchar</code> field, saving some space.

But, now-a-days, most of the applications being developed are international, so you'd yourself have to decide which all users will be signing up, and based on that decide the datatype.

blocks|key|1508560|text|我认为nvarchar是|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1508561|的两倍。|blockquote|1508562|1508563|1508564|是。|1508565|1508566|+nvarchar用于国际化。|1508567|1508568|1508569|1508570|你建议我应该使用|1508571|还是varchar？|1508572|1508573|1508574|这取决于应用程序。|1508575|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Z|8|@]|9|@]|A|$]]|$1|E|3|-4|5|6|7|10|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|11|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|12|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|13|8|@]|9|@]|A|$]]|$1|J|3|K|5|D|7|14|8|@]|9|@]|A|$]]|$1|L|3|-4|5|6|7|15|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|16|8|@]|9|@]|A|$]]|$1|N|3|H|5|6|7|17|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|18|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|19|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|T|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|1C|8|@]|9|@]|A|$]]|$1|W|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]]|X|$]]

<blockquote>
 I have red that nvarchar takes twice as varchar.
</blockquote>

Yes.

<blockquote>
 nvarchar is used for internationalization.
</blockquote>

Yes.

<blockquote>
 what u suggest should i use nvarchar or varchar?
</blockquote>

It's depends upon the application.

blocks|key|1289946|text|默认情况下，使用nvarchar。现在几乎没有理由使用varchar，而完全有理由使用nvarchar+(允许使用国际字符；正如所讨论的那样)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1289947|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

By default go with nvarchar. There is very little reason to go with varchar these days, and every reason to go with nvarchar (allows international characters; as discussed).

blocks|key|1508642|text|varchar是每个字符1个字节，nvarchar是每个字符2个字节。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1508643|对于nvarchar，您将使用更多的空间，但是还有更多允许的字符。额外的空间可以忽略不计，但将来您可能会错过这些额外的字符。即使你不希望需要国际化，人们的名字中也通常会有非英语字符(例如é，ñorö)。|1508644|我建议您使用nvarchar。|1508645|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

varchar is 1 byte per character, nvarchar is 2 bytes per character.

You will use more space with nvarchar but there are many more allowable characters. The extra space is negligible, but you may miss those extra characters in the future. Even if you don't expect to require internationalization, people will often have non-English characters (e.g. é, ñ or ö) in their names.

I would suggest you use nvarchar.

blocks|key|4506557|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4506558|我说过nvarchar是varchar的两倍|blockquote|4506559|4506560|4506561|是。根据微软的说法：“存储大小，以字节为单位，是输入字符数%2B2字节的两倍”(http://msdn.microsoft.com/en-us/library/ms186939(SQL.90).aspx。|offset|length|4506562|但是存储很便宜；我从不担心额外的几个字节。|4506563|此外，还可以省去将来的麻烦，将最大宽度设置为更大的值，比如100个字符。当您使用varchar或nvarchar+(而不是char/nchar)时，绝对不会产生存储开销。你永远不会知道什么时候你会遇到一个三个桶的姓氏或某个超过30个字符的长长的外国名字。|4506564|4506565|+nvarchar用于国际化。|4506566|4506567|4506568|nvarchar可以存储任何unicode字符，例如来自非拉丁文字(阿拉伯语、中文等)的字符。我不确定您的应用程序将如何获取数据(通过web、通过GUI工具包等)，但您正在使用的任何技术都可能支持开箱即用的unicode。这意味着对于任何用户输入的数据(如姓名)，总是有可能接收非拉丁字符，如果不是现在，那就是将来。|4506569|如果我正在构建一个新的应用程序，我会使用nvarchar。如果你愿意，可以称之为“面向未来”。|4506570|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/ms186939(SQL.90%2529.aspx)^0|0|0|0|0|12|1P|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|-4|4|5|6|14|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|15|7|@]|8|@]|9|$]]|$1|D|3|-4|4|5|6|16|7|@]|8|@]|9|$]]|$1|E|3|-4|4|5|6|17|7|@]|8|@]|9|$]]|$1|F|3|G|4|5|6|18|7|@]|8|@$H|19|I|1A|1|1B]]|9|$]]|$1|J|3|K|4|5|6|1C|7|@]|8|@]|9|$]]|$1|L|3|M|4|5|6|1D|7|@]|8|@]|9|$]]|$1|N|3|-4|4|5|6|1E|7|@]|8|@]|9|$]]|$1|O|3|P|4|C|6|1F|7|@]|8|@]|9|$]]|$1|Q|3|-4|4|5|6|1G|7|@]|8|@]|9|$]]|$1|R|3|-4|4|5|6|1H|7|@]|8|@]|9|$]]|$1|S|3|T|4|5|6|1I|7|@]|8|@]|9|$]]|$1|U|3|V|4|5|6|1J|7|@]|8|@]|9|$]]|$1|W|3|-4|4|5|6|1K|7|@]|8|@]|9|$]]]|X|$Y|$4|Z|10|11|9|$12|13]]]]

<blockquote>
 I have red that nvarchar takes twice as varchar
</blockquote>

Yes. According to Microsoft: "Storage size, in bytes, is two times the number of characters entered + 2 bytes" (<a href="http://msdn.microsoft.com/en-us/library/ms186939(SQL.90).aspx" rel="nofollow noreferrer">http://msdn.microsoft.com/en-us/library/ms186939(SQL.90).aspx</a>).

But storage is cheap; I never worry about a few extra bytes.

Also, save yourself trouble in the future and set the maximum widths to something more generous, like 100 characters. There is absolutely no storage overhead to this when you're using varchar or nvarchar (as opposed to char/nchar). You never know when you're going to encounter a triple-barrelled surname or some long foreign name which exceeds 30 characters.

<blockquote>
 nvarchar is used for internationalization.
</blockquote>

nvarchar can store any unicode character, such as characters from non-Latin scripts (Arabic, Chinese, etc). I'm not sure how your application will be taking data (via the web, via a GUI toolkit, etc) but it's likely that whatever technology you're using supports unicode out of the box. That means that for any user-entered data (such as name) there is always the possibility of receiving non-Latin characters, if not now then in the future.

If I was building a new application, I would use nvarchar. Call it "future-proofing" if you like.

blocks|key|1290068|text|nvarchar类型是Unicode，因此它几乎可以处理地球上每种语言中存在的任何字符。字符存储为UTF-16或UCS-2+(不确定是哪种格式，差别很小)，因此每个字符使用两个字节。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1290069|varchar类型使用8位字符集，因此它被限制为您为字段选择的字符集的255个字符。有不同的字符集来处理不同的字符组，因此对于一个国家或地区的本地文本来说，这通常就足够了。|1290070|如果varchar可以做你想做的事情，你应该使用它。它的数据量要少一点，所以总体上会稍微快一点。如果需要处理各种字符，请使用nvarchar。|1290071|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|H|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|I|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|J|8|@]|9|@]|A|$]]|$1|F|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|G|$]]

The nvarchar type is Unicode, so it can handle just about any character that exist in every language on the planet. The characters are stored as UTF-16 or UCS-2 (not sure which, and the differences are subtle), so each character uses two bytes.

The varchar type uses an 8 bit character set, so it's limited to the 255 characters of the character set that you choose for the field. There are different character set that handles different character groups, so it's usually sufficient for text local to a country or a region.

If varchar works for what you want to do, you should use that. It's a bit less data, so it's overall slightly faster. If you need to handle a wide variety of characters, use nvarchar.

blocks|key|1290219|text|在性能方面：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1290220|使用varchar而不是nvarchar的一个原因是，索引中的字符可以是nvarchar的两倍！索引键限制为900字节|1290221|关于可用性：|1290222|如果应用程序仅供英语用户使用且包含英文名称，请使用varchar|1290223|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|L|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|M|8|@]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

on performance: 
a reason to use varchar over nvarchar is that you can have twice as many characters in your indexes! index keys are limited to 900 bytes 
on usability: 
if the application is only ever intended for a english audience &amp; contain english names, use varchar

blocks|key|1510261|text|要存储的数据："Sunil“|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1510262|varchar(5)占用7B+nvarchar(5)占用12B|1510263|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Data to store: "Sunil"

varchar(5) takes 7B
nvarchar(5) takes 12B

I am storing first name and last name with up to 30 characters each. Which is better <code>varchar</code> or <code>nvarchar</code>.

I have read that <code>nvarchar</code> takes up twice as much space compared to <code>varchar</code> and that <code>nvarchar</code> is used for internationalization. 

So what do you suggest should I use: <code>nvarchar</code> or <code>varchar</code> ?

Also please let me know about the performance of both. Is performance for both is same or they differ in performance. Because space is not too big issue. Issue is the performance.

varchar or nvarchar

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。

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我正在存储名字和姓氏，每个名字最多包含30个字符。varchar和nvarchar哪个更好。我读到过，与varchar相比，nvarchar占用了两倍的空间，而且nvarchar用于国际化。那么你建议我应该使用什么呢：nvarchar还是varchar？另外，请让我知道这两个的表现。两者的性能是相同还是不同。因为空间不是太大的问题。问题在于性能。

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