How to handle System.DBNull?

Question

I have a object with type:

dynamic {System.DBNull}

I want to check it:

if (myObject!= null || myObject!= DBNull.Value)
{
   MessageBox.Show("Oh hi");
}

But the MessageBox always appears. Whats wrong, is it another type?

Answer 1

This expression is always true

myObject != null || myObject != DBNull.Value

because myObject cannot be null and DBNull.Value at the same time. Replace || with && to fix.

Answer 2

Try this code

if(myObject != DBNull.Value)
{
   MessageBox.Show("Oh hi");
}

or

if(myObject != null && myObject != DBNull.Value)
{
   MessageBox.Show("Oh hi");
}

Answer 3

There is also a function for checking for DBNull:

if(myObject != null && !Convert.IsDBNull(myObject))
{
   MessageBox.Show("Oh hi");
}