More In-Depth About Nulls And DBNull
page 1 of 7
Published: 08 Nov 2007
Abstract
I see a lot on forums the question being asked about DBNull, and why it may cause problems when you read values from a reader, or try to assign it to a value type. This article delves into DBNull more explicitly and shows the differences between various objects.
by Brian Mains
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Introduction

The DBNull class is a special situation when it comes to working with the ADO.NET framework, and even though it's mostly straightforward, I still see a lot of confusion about how it can be used.  So I am writing this in hopes that this may alleviate someone's problems in the future.


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User Comments

Title: Nasty syntax for getting round this   
Name: Tyrannosaurs
Date: 2008-02-20 11:50:11 AM
Comment:
You cast a null date time to a dbnull like this:

datetime? myDateTime;

myDateTime = null;

.... parameters.add(...).value = (object)myDateTime ?? System.DBNull.Value;

It's pretty horrible but works and is no worse than most of the alternatives.
Title: DBNULL   
Name: g
Date: 2007-11-19 6:37:19 AM
Comment:
this concept can be dealt in more detail
Title: Datetime & DBNull Reply   
Name: Brian
Date: 2007-11-10 11:29:55 PM
Comment:
You can't cast directly; DBNULL and DateTIme are two separate object types, and you can't cast one to the other. However, in an ADO.NET datarow object, the underlying value is object, which could accept both. However, if the field is not null, then you can't assign a null value to it. It all depends on your code.
Title: Datetime&DBnull   
Name: Erick
Date: 2007-11-09 6:49:21 AM
Comment:
When I assigned DBNull.Value to System.Datetime, it raised a exception. Can I set a Datetime field of the database to null by using DBNull.Value in ADO.net?






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