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New Message on MumbaiUserGroup

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From: TakeoverAnu
Message 8 in Discussion

Difference between Null and DBNull :


A null value is a value that doesn't refer to any object. It's the default 
value of reference-type variables (e.g., class, interface, delegate).The null 
keyword is a literal that represents a null reference with the C# .NET 
environment. You may use the null keyword to check or assign the value of an 
object.

The use of the DBNull class indicates the absence of a known value. While the 
Microsoft documentation says it's typically in a database application, you may 
also use it with any type of data. In database applications, a null object is a 
valid value for a field. This class differentiates between a null value (a null 
object) and an uninitialised value (the DBNull.Value instance). For example, a 
table can have records with uninitialised fields. By default, these 
uninitialised fields have the DBNull value. You can utilise the DBNull object 
by way of its Value property. This represents a null value, which is never 
equal to anything.

Substantial difference between them is that if you put a null value in 
SqlParameter, though the parameter did not exist, but if you put in 
DBNull.Value, the parameter is included with a null value. same like COM 
interop thing with VT_NULL and VT_EMPTY


And have you noticed that contrary to the docs, and contrary to SQL as well, 
DBNull.Value.Equals(DBNull.Value) is true? 

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