Handling null values returned via SQL query 2

[jasonp45]

How do I test for and handle a return of null in the following code?

                try
                {
                    OleDbConnection connection = new OleDbConnection(connectionString);
                    connection.Open();
                    OleDbCommand command = new OleDbCommand(SQL_Query, connection);
                    scalarReturned = command.ExecuteScalar().ToString();
                    command.Dispose();
                    connection.Close();
                }
                catch (Exception ex)
                {
                    
                }

This is part of a data-handling class I'm building, and I use this method for pulling single values from one of my lookup tables where the structure is fixed. It works fine; however I want to be able to handle when the query returns null...of course trying to convert null ToString() generates an error.

I suppose I could just trap that error, but I'd rather design it so no error is generated.

Thanks.

 

[litton1]

you could do something like

object scalarReturned = command.ExecuteScalar().ToString();

if(scalarReturned!= null)
{
  ....
}

// or if it is always an int that you are expecting
int myInt;
Int32.TryParse(scalarReturned.ToString(), out myInt);
if (myInt == 0)
{
    Console.WriteLine("Nothing returned");
}

Age is a consequence of experience

 

[litton1]

sorry this line should read

object scalarReturned = command.ExecuteScalar();

copy and paste error

Age is a consequence of experience

 

[dseaver]

You could do a Convert.ToInt32 also. DbNull.value gets turned into a 0 when converted/tryparsed

 

[litton1]

Glad i could help, thanks for the star!

Age is a consequence of experience

 

[jasonp45]

Final working code:

object oScalarReturned = new Object();
oScalarReturned = command.ExecuteScalar();
if (oScalarReturned is DBNull || oScalarReturned == null)
    scalarReturned = "";
else
    scalarReturned = oScalarReturned.ToString();