Inserting NULL to SQL DB from C# DbCommand

Question

        DbParameter param = comm.CreateParameter();
        param = comm.CreateParameter();
        param.ParameterName = "@StaffId";
        if (!string.IsNullOrEmpty(activity.StaffId))
            param.Value = activity.StaffId;
        param.DbType = DbType.String;
        comm.Parameters.Add(param);

The above does not work (obviously), object not instantiated. I am attempting to insert a NULL into the database when StaffId is NOT populated. How can I achieve this?

Conceive

you can use DBNull.Value – Telemark

Perfect! If you post this as answer I'll mark it as correct. – Conceive

As for why... https://mcmap.net/q/205220/-what-is-the-point-of-dbnull/… – Winterize

Answer 1

You can use DBNull.Value when you need to pass NULL as a parameter to the stored procedure.

param.Value = DBNull.Value;

Or you can use that instead of your if operator:

param.Value = !string.IsNullOrEmpty(activity.StaffId) ? activity.StaffId : (object)DBNull.Value;

Telemark

Thanks for the edit Andrey - appreciate it. It seems crazy to have to cast this as an object though (to me anyway). – Conceive

Answer 2

Try DBNull.Value

if (!string.IsNullOrEmpty(activity.StaffId))
   param.Value = activity.StaffId;
else
  param.Value=DBNull.Value;

Disney

is there a way of using the ? operator for a sort of shorthand if else statement here?? It seems to not like the String/DBNull.Value conversion!? – Conceive

Try this: param.Value = !string.IsNullOrEmpty(activity.StaffId) ? activity.StaffId : (object)DBNull.Value; – Telemark

Answer 3

You can always use the null-coalescing operator (??)

param.Value = activity.StaffId ?? (object)DBNull.Value;

Lust

Answer 4

You could use DBNull.Value:

param.Value = DBNull.Value;

Ermine