Use the .ToString() method of your database object, then use the
string.IsNullOrEmpty method to test for null
For example, if you are working with a Datarow you would do something
of the sort
string s = dstWastage.Audit[0].ToString();
if(string.IsNullOrEmpty(s))
{
......
Oh, and when working with strings in .net, use the .Equals method
instead of ==
On Jan 31, 8:21 am, JaffaB <[email protected]> wrote:
> Hi All,
>
> i am trying to use a variable from a DST in a VS2003 project, and I am
> trying to overcome an Invalid Cast Exception of DBnull. But
> everything I try to test for DBnull, causes the exception as well.
>
> At first, I used a function to check and convert as follows:
>
> public static string MNS(object s)
> {
> if(s==System.DBNull.Value)
> return string.Empty;
> else
> return Convert.ToString(s);
> }
>
> However, calling this (passing in the column of the table as shown
> below) caused the same casting exception. Now I have gone specific
> with the test as follows:
>
> DstWastage.AuditRow drAudit = dstWastage.Audit[0];
> if(drAudit.ContainerCode.Equals(System.DBNull.Value) == true) sqlains
> = SqlCEParamAdd(sqlains,""); else sqlains = SqlCEParamAdd
> (sqlains,drAudit.ContainerCode);
>
> the 2nd line, produces the exception error of Invalid Cast Exception :
> StrongTyping_CannotAccessDBNull.
>
> I have also tried..
>
> DstWastage.AuditRow drAudit = dstWastage.Audit[0];
> if(drAudit.ContainerCode == System.DBNull.Value) sqlains =
> SqlCEParamAdd(sqlains,""); else sqlains = SqlCEParamAdd
> (sqlains,drAudit.ContainerCode);
>
> However, this wont even compile, as it says it cannot compare the
> string (drAudit.ContainerCode) with a type of System.DBNull.Value
>
> Can anybody point me in the right direction for sorting out whether
> the variable is a DBnull or not.
