可空类型 [英] Nullable Types

问题描述

我刚刚在net 2.0中发表了关于Nullable类型的一些内容。
http://stevenr2.blogspot.com/2006/01...oalescing.html


问题至于为什么你不能简单地从

..Net值类型转换为Sql Server数据类型，而不是必须使用null

cheked和DBNull.Value？


有没有人有一些解释为什么这是如此棘手呢？

包括在内？
http://stevenR2.com

I''ve just blogged some stuff on Nullable types in net 2.0.
http://stevenr2.blogspot.com/2006/01...oalescing.html

Question however as to why you can''t simply get an implcit conversion from a
..Net value type to to a Sql Server data type rather than having to use null
cheked and DBNull.Value ?

Does anyone have some explanation as to why this is so tricky as to be
included?

http://stevenR2.com

推荐答案

当然我的意思是 - 不包括在内...... :)


" Steven Livingstone" <共***** @ NOSPAM.stevenR2.com>在留言中写道

news：％2 *************** @ tk2msftngp13.phx.gbl ...

of course i meant - as not to be included... :)

"Steven Livingstone" <co*****@NOSPAM.stevenR2.com> wrote in message
news:%2***************@tk2msftngp13.phx.gbl...

我是我刚刚在net 2.0中发表了关于Nullable类型的一些内容。
http://stevenr2.blogspot.com/2006/01...oalescing.html

然而问题为什么你不能简单获得从.Net值类型到Sql Server数据类型的implcit转换，而不是必须使用
null cheked和DBNull.Value？

有没有人有一些解释至于为什么要包括这么简单？

http： //stevenR2.com

I''ve just blogged some stuff on Nullable types in net 2.0.
http://stevenr2.blogspot.com/2006/01...oalescing.html

Question however as to why you can''t simply get an implcit conversion from
a .Net value type to to a Sql Server data type rather than having to use
null cheked and DBNull.Value ?

Does anyone have some explanation as to why this is so tricky as to be
included?

http://stevenR2.com

FWIW，有一段时间讨论了这个问题（
$ b $至少VB的一部分，你必须假设C＃）。

http://blogs.msdn.com/vbteam/archive...13.aspx#159656


似乎MS认为它。所以，要么我错过了一些东西，它已经完成了，或者他们选择不这样做。


史蒂文:: http://stevenR2.com

" Steven Livingstone" <共***** @ NOSPAM.stevenR2.com>在留言中写道

news：％2 *************** @ tk2msftngp13.phx.gbl ...

FWIW, there was a discussion a while back where this was considered (at
least a part of VB and you''d have to assume C#).

http://blogs.msdn.com/vbteam/archive...13.aspx#159656

Seems MS considered it. So either i''m missing something and it''s already
done, or they chose not to do it.

steven :: http://stevenR2.com
"Steven Livingstone" <co*****@NOSPAM.stevenR2.com> wrote in message
news:%2***************@tk2msftngp13.phx.gbl...

我是我刚刚在net 2.0中发表了关于Nullable类型的一些内容。
http://stevenr2.blogspot.com/2006/01...oalescing.html

然而问题为什么你不能简单获得从.Net值类型到Sql Server数据类型的implcit转换，而不是必须使用
null cheked和DBNull.Value？

有没有人有一些解释至于为什么要包括这么简单？

http： //stevenR2.com

I''ve just blogged some stuff on Nullable types in net 2.0.
http://stevenr2.blogspot.com/2006/01...oalescing.html

Question however as to why you can''t simply get an implcit conversion from
a .Net value type to to a Sql Server data type rather than having to use
null cheked and DBNull.Value ?

Does anyone have some explanation as to why this is so tricky as to be
included?

http://stevenR2.com

史蒂文，


这不是很棘手，真的。 SQL可空类型意味着特定域空间的特定解决方案。 Nullable类型扩展

到更大的空间。


另外，我相信可以为空的类型是替代品，而不是

一个互操作机制。


我不知道这肯定是合理的。


如果有的话，我认为SQL nullables将会消失（意思是，

它们将留在那里以实现向后兼容性），现在已经有了一般的

解决方案。


希望这会有所帮助。

" Steven Livingstone" <共***** @ NOSPAM.stevenR2.com>在留言中写道

news：％2 *************** @ tk2msftngp13.phx.gbl ...

Steven,

It''s not tricky, really. The SQL nullable types were meant as a very
specific solution to a particular domain space. Nullable types are extended
to a much larger space.

Also, I believe that nullable types are meant to be a replacement, not
an interop mechanism.

I don''t know that this necessarily justifies it, though.

If anything, I think that the SQL nullables will just go away (meaning,
they will be left in there for backwards compatability), now that a general
solution is in place.

Hope this helps.
"Steven Livingstone" <co*****@NOSPAM.stevenR2.com> wrote in message
news:%2***************@tk2msftngp13.phx.gbl...

我是我刚刚在net 2.0中发表了关于Nullable类型的一些内容。
http://stevenr2.blogspot.com/2006/01...oalescing.html

然而问题为什么你不能简单获得从.Net值类型到Sql Server数据类型的implcit转换，而不是必须使用
null cheked和DBNull.Value？

有没有人有一些解释至于为什么要包括这么简单？

http： //stevenR2.com

I''ve just blogged some stuff on Nullable types in net 2.0.
http://stevenr2.blogspot.com/2006/01...oalescing.html

Question however as to why you can''t simply get an implcit conversion from
a .Net value type to to a Sql Server data type rather than having to use
null cheked and DBNull.Value ?

Does anyone have some explanation as to why this is so tricky as to be
included?

http://stevenR2.com

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