hi
i have write this code to insert data from Asp.net to sql server table and it is work perfectly but

i need to insert just t1 column i don't need t3 to be inserted
how can i do it?
i have tried to write t3=null but it don't work


this is the code::::::::::::
SqlConnection cs = new SqlConnection("Data Source=MyPc;Initial Catalog=try;Integrated Security=True");
SqlDataAdapter da = new SqlDataAdapter();
da.InsertCommand = new SqlCommand("INSERT INTO test(t1,t3) VALUES(@t1,@t3)", cs);
da.InsertCommand.Parameters.Add("@t1", SqlDbType.VarChar).Value =TextBox1.Text;
da.InsertCommand.Parameters.Add("@t3", SqlDbType.VarChar).Value = TextBox1.Text;
cs.Open();
da.InsertCommand.ExecuteNonQuery();
cs.Close();