Question

I am returning a scalar value from a SQL Server 2008 database:

string reason = cmd.ExecuteScalar().ToString() ?? : "";

I want to make sure that if null is returned, that reason = "" and not null.

i am getting an error on this line:

Error 3 Invalid expression term ‘:’

How can this be fixed?

EDIT:

thank you for the changes on the colon, now i am getting this exception on the same line:

string reason = cmd.ExecuteScalar().ToString() ?? "";

System.NullReferenceException occurred
  Message="Object reference not set to an instance of an object."

Answer 1

Try this:

string reason = cmd.ExecuteScalar().ToString() ?? "";

BUT: this will still fail, since if .ExecuteScalar() returns a NULL, you’re already causing a Null Reference Exception by calling .ToString() on that NULL value……

So I guess the ?? operator really doesn’t help you here… do the “usual” dance:

object result = cmd.ExecuteScalar();

if(result != null)
{  
   reason = result.ToString();
}
else
{
   reason = "(NULL value returned)";
}