Question

I was previously taught today how to set parameters in a SQL query in .NET in this answer (click).

Using parameters with values are fine, but when I try to set a field in the database to null I’m unsuccessful. Either the method thinks I am not setting a valid parameter or not specifying a parameter.

e.g.

Dim dc As New SqlCommand('UPDATE Activities SET [Limit] = @Limit WHERE [Activity] = @Activity', cn)  If actLimit.ToLower() = 'unlimited' Then     ' It's not nulling :(     dc.Parameters.Add(New SqlParameter('Limit', Nothing)) Else     dc.Parameters.Add(New SqlParameter('Limit', ProtectAgainstXSS(actLimit))) End If 

Is there something I’m missing? Am I doing it wrong?

Answer 1

you want DBNull.Value.

In my shared DAL code, I use a helper method that just does:

    foreach (IDataParameter param in cmd.Parameters)     {         if (param.Value == null) param.Value = DBNull.Value;     }