T-SQL转换与转换 [英] T-SQL Cast versus Convert

问题描述

关于何时应使用 CAST 与 CONVERT 的一般指导原则是什么？有选择一个与另一个相关的性能问题吗？是否更接近ANSI-SQL？

What is the general guidance on when you should use CAST versus CONVERT? Is there any performance issues related to choosing one versus the other? Is one closer to ANSI-SQL?

推荐答案

CONVERT 是SQL Server具体， CAST 是ANSI。

CONVERT is SQL Server specific, CAST is ANSI.

CONVERT 灵活的，你可以格式化日期等。除此之外，他们几乎是一样的。如果您不关心扩展功能，请使用 CAST 。

CONVERT is more flexible in that you can format dates etc. Other than that, they are pretty much the same. If you don't care about the extended features, use CAST.

编辑：

如下面注释中@beruic和@CF所指出的，当使用隐式转换（即既不使用CAST也不使用CONVERT）时，可能会丢失精度。有关详细信息，请参见 CAST和CONVERT ，特别是此图形：< a href =http://www.microsoft.com/en-us/download/confirmation.aspx?id=35834 =noreferrer> SQL Server数据类型转换图表。有了这些额外的信息，原来的建议仍然保持不变。尽可能使用CAST。

As noted by @beruic and @C-F in the comments below, there is possible loss of precision when an implicit conversion is used (that is one where you use neither CAST nor CONVERT). For further information, see CAST and CONVERT and in particular this graphic: SQL Server Data Type Conversion Chart. With this extra information, the original advice still remains the same. Use CAST where possible.

这篇关于T-SQL转换与转换的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！