How to test for DBNull when using ExecuteScalar?

I have the code below.  It returns DBNull and crashes.  How do I test for DBNull using ExecuteScalar?
string selectStatement = "select sum(cast(NbrOfCopies as integer)) from tBooks";
            FbCommand cmd = new FbCommand(selectStatement, bookConn);
            if (bookConn.State == ConnectionState.Closed)
                bookConn.Open();
            int Count = Convert.ToInt32(cmd.ExecuteScalar());  //  <-- crashes here!
            lblTotalCount.Text = "Total In Inventory:    " + Count.ToString();

Open in new window

rmmarshAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

matthewrhoadesCommented:
I would add another line for the conversion.

Sorry for the sloppy looking formatting.
ing selectStatement = "select sum(cast(NbrOfCopies as integer)) from tBooks";
            FbCommand cmd = new FbCommand(selectStatement, bookConn);
            if (bookConn.State == ConnectionState.Closed)
                bookConn.Open();
            int Count = cmd.ExecuteScalar();  //  <-- crashes here!
if isDBNull(Count) = False then
myCount = ToInt32.Convert(Count)
            lblTotalCount.Text = "Total In Inventory:    " + myCount.ToString();

Open in new window

0
matthewrhoadesCommented:
Rather...
ing selectStatement = "select sum(cast(NbrOfCopies as integer)) from tBooks";
            FbCommand cmd = new FbCommand(selectStatement, bookConn);
            if (bookConn.State == ConnectionState.Closed)
                bookConn.Open();
            int Count = cmd.ExecuteScalar();  //  <-- crashes here!
            If IsDBNull(Count) = False Then
                myCount = ToInt32.Convert(Count)
            End If
            lblTotalCount.Text = "Total In Inventory:    " + myCount.ToString();
            myInternalConnection.Close()

Open in new window

0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
rmmarshAuthor Commented:
I found a better way:  

            int Count = cmd.ExecuteScalar() is DBNull ? 0 : Convert.ToInt32(cmd.ExecuteScalar());



But thank you for putting me on the right track...
0
Guy Hengel [angelIII / a3]Billing EngineerCommented:
mmarsh: your "better" method risks to run the command object 2 times!!!!

hence:


object result = cmd.ExecuteScalar();
int Count = (result == DBNull.Value ? 0 : Convert.ToInt32(result));

Open in new window

0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
.NET Programming

From novice to tech pro — start learning today.