We have our own ORM we use here, and provide strongly typed wrappers for all of our db tables. We also allow weakly typed ad-hoc SQL to be executed, but these queries still go through the same class for getting values out of a data reader.
我们在这里使用自己的ORM,并为所有db表提供强类型包装器。我们还允许执行弱类型的临时SQL,但这些查询仍然通过相同的类来从数据读取器中获取值。
In tweaking that class to work with Oracle, we've come across an interesting question. Is it better to use DBNull.Value, or null? Are there any benefits to using DBNull.Value? It seems more "correct" to use null, since we've separated ourselves from the DB world, but there are implications (you can't just blindly ToString() when a value is null for example) so its definitely something we need to make a conscious decision about.
在调整该类以使用Oracle时,我们遇到了一个有趣的问题。使用DBNull.Value或null是否更好?使用DBNull.Value有什么好处吗?使用null似乎更“正确”,因为我们已经将自己从数据库世界中分离出来,但是有一些含义(例如,当值为null时,你不能盲目地使用ToString())所以它绝对是我们需要的东西做出有意识的决定。
4 个解决方案
#1
15
I find it better to use null, instead of DB null.
我发现使用null更好,而不是DB null。
The reason is because, as you said, you're separating yourself from the DB world.
原因是,正如您所说,您将自己与数据库世界分开。
It is generally good practice to check reference types to ensure they aren't null anyway. You're going to be checking for null for things other than DB data, and I find it is best to keep consistency across the system, and use null, not DBNull.
通常,检查引用类型以确保它们不为空是一种很好的做法。您将检查除DB数据之外的其他内容的null,并且我发现最好保持整个系统的一致性,并使用null,而不是DBNull。
In the long run, architecturally I find it to be the better solution.
从长远来看,在架构上我发现它是更好的解决方案。
#2
7
If you've written your own ORM, then I would say just use null, since you can use it however you want. I believe DBNull was originally used only to get around the fact that value types (int, DateTime, etc.) could not be null, so rather than return some value like zero or DateTime.Min, which would imply a null (bad, bad), they created DBNull to indicate this. Maybe there was more to it, but I always assumed that was the reason. However, now that we have nullable types in C# 3.0, DBNull is no longer necessary. In fact, LINQ to SQL just uses null all over the place. No problem at all. Embrace the future... use null. ;-)
如果您已经编写了自己的ORM,那么我会说只使用null,因为您可以根据需要使用它。我相信DBNull最初只是用于解决值类型(int,DateTime等)不能为空的事实,所以不要返回像zero或DateTime.Min这样的值,这意味着null(坏,坏) ),他们创建了DBNull来表明这一点。也许还有更多,但我一直认为这就是原因。但是,现在我们在C#3.0中有可空类型,不再需要DBNull。实际上,LINQ to SQL只是在所有地方使用null。没问题。拥抱未来......使用null。 ;-)
#3
3
From the experience I've had, the .NET DataTables and TableAdapters work better with DBNull. It also opens up a few special methods when strongly typed, such as DataRow.IsFirstNameNull when in place.
根据我的经验,.NET DataTables和TableAdapter可以更好地与DBNull配合使用。当强类型时,它还会打开一些特殊方法,例如DataRow.IsFirstNameNull。
I wish I could give you a better technical answer than that, but for me the bottom line is use DBNull when working with the database related objects and then use a "standard" null when I'm dealing with objects and .NET related code.
我希望我能给你一个比这更好的技术答案,但对我来说,底线是在处理数据库相关对象时使用DBNull,然后在处理对象和.NET相关代码时使用“标准”null。
#4
1
Use DBNull.
We encouintered some sort of problems when using null.
If I recall correctly you cannot INSERT a null value to a field, only DBNull.
Could be Oracle related only, sorry, I do not know the details anymore.
使用DBNull。我们在使用null时鼓励出现某种问题。如果我没记错,你不能将空值插入字段,只有DBNull。可能只与甲骨文有关,对不起,我不知道细节了。
#1
15
I find it better to use null, instead of DB null.
我发现使用null更好,而不是DB null。
The reason is because, as you said, you're separating yourself from the DB world.
原因是,正如您所说,您将自己与数据库世界分开。
It is generally good practice to check reference types to ensure they aren't null anyway. You're going to be checking for null for things other than DB data, and I find it is best to keep consistency across the system, and use null, not DBNull.
通常,检查引用类型以确保它们不为空是一种很好的做法。您将检查除DB数据之外的其他内容的null,并且我发现最好保持整个系统的一致性,并使用null,而不是DBNull。
In the long run, architecturally I find it to be the better solution.
从长远来看,在架构上我发现它是更好的解决方案。
#2
7
If you've written your own ORM, then I would say just use null, since you can use it however you want. I believe DBNull was originally used only to get around the fact that value types (int, DateTime, etc.) could not be null, so rather than return some value like zero or DateTime.Min, which would imply a null (bad, bad), they created DBNull to indicate this. Maybe there was more to it, but I always assumed that was the reason. However, now that we have nullable types in C# 3.0, DBNull is no longer necessary. In fact, LINQ to SQL just uses null all over the place. No problem at all. Embrace the future... use null. ;-)
如果您已经编写了自己的ORM,那么我会说只使用null,因为您可以根据需要使用它。我相信DBNull最初只是用于解决值类型(int,DateTime等)不能为空的事实,所以不要返回像zero或DateTime.Min这样的值,这意味着null(坏,坏) ),他们创建了DBNull来表明这一点。也许还有更多,但我一直认为这就是原因。但是,现在我们在C#3.0中有可空类型,不再需要DBNull。实际上,LINQ to SQL只是在所有地方使用null。没问题。拥抱未来......使用null。 ;-)
#3
3
From the experience I've had, the .NET DataTables and TableAdapters work better with DBNull. It also opens up a few special methods when strongly typed, such as DataRow.IsFirstNameNull when in place.
根据我的经验,.NET DataTables和TableAdapter可以更好地与DBNull配合使用。当强类型时,它还会打开一些特殊方法,例如DataRow.IsFirstNameNull。
I wish I could give you a better technical answer than that, but for me the bottom line is use DBNull when working with the database related objects and then use a "standard" null when I'm dealing with objects and .NET related code.
我希望我能给你一个比这更好的技术答案,但对我来说,底线是在处理数据库相关对象时使用DBNull,然后在处理对象和.NET相关代码时使用“标准”null。
#4
1
Use DBNull.
We encouintered some sort of problems when using null.
If I recall correctly you cannot INSERT a null value to a field, only DBNull.
Could be Oracle related only, sorry, I do not know the details anymore.
使用DBNull。我们在使用null时鼓励出现某种问题。如果我没记错,你不能将空值插入字段,只有DBNull。可能只与甲骨文有关,对不起,我不知道细节了。