Nvarchar将在内存、存储、工作集和索引方面有很大的开销，所以如果规格规定它真的永远都不需要，那就别费心了。

我不会有一个硬性的“总是nvarchar”规则，因为它在许多情况下完全是浪费——特别是来自ASCII/EBCDIC的ETL或标识符和代码列，它们通常是键和外键。

另一方面，有很多列的情况，在这些情况下，我肯定会在早期提出这个问题，如果我没有立即得到一个明确而快速的答案，我将使列为nvarchar。

我在工作中经常遇到这样的问题:

库存和定价的FTP提要-当varchar工作正常时，项目描述和其他文本是在nvarchar中。将这些文件转换为varchar可以将文件大小减少近一半，并且对上传非常有帮助。 上面的场景工作得很好，直到有人在商品描述中添加了一个特殊字符(可能是商标，不记得了)

我还是不会每次都用varchar。如果有任何疑问或特殊字符的潜力，我使用nvarchar。我发现，当我100%控制填充字段的内容时，我主要使用varchar。

由于您的应用程序很小，使用nvarchar与使用varchar相比，基本上没有明显的成本增加，而且如果您需要存储unicode数据，您也省去了潜在的麻烦。

如果您使用NVARCHAR只是因为系统存储过程需要它，最常见的情况是莫名其妙的sp_executesql，并且您的动态SQL非常长，那么从性能角度来看，您最好在VARCHAR中进行所有字符串操作(连接、替换等)，然后将最终结果转换为NVARCHAR并将其输入到proc参数中。所以，不要总是使用NVARCHAR!

For your application, nvarchar is fine because the database size is small. Saying "always use nvarchar" is a vast oversimplification. If you're not required to store things like Kanji or other crazy characters, use VARCHAR, it'll use a lot less space. My predecessor at my current job designed something using NVARCHAR when it wasn't needed. We recently switched it to VARCHAR and saved 15 GB on just that table (it was highly written to). Furthermore, if you then have an index on that table and you want to include that column or make a composite index, you've just made your index file size larger.

做决定时要考虑周全;在SQL开发和数据定义中，似乎很少有“默认答案”(当然，除了不惜一切代价避免游标)。

I can speak from experience on this, beware of nvarchar. Unless you absolutely require it this data field type destroys performance on larger database. I inherited a database that was hurting in terms of performance and space. We were able to reduce a 30GB database in size by 70%! There were some other modifications made to help with performance but I'm sure the varchar's helped out significantly with that as well. If your database has the potential for growing tables to a million + records stay away from nvarchar at all costs.