Can you just pass null without casting to Int64?

>I am re-writing my code now this way:
>
>

>  SqlParameter gstPassNo = insertCommand.Parameters.Add("@gstPassNo", SqlDbType.Decimal, 17);
>                if (this.passTable == PassTable.Gst_Pass)
>                    gstPassNo.Value =   passNo;
>                else 
>                    gstPassNo.Value = DBNull.Value;
>

>
>after finding this link
>
>http://stackoverflow.com/questions/4555935/how-to-assign-null-to-a-sqlparameter