我有一段代码可能会返回“未找到结果-null”
String result
string searchUby = "SELECT text FROM rooms WHERE year=@year AND event=@eventAND text=@text AND z is NULL";
SqlCommand sqlcom = new SqlCommand(searchUby, conn);
sqlcom.Parameters.AddWithValue("@event",event.Text);
sqlcom.Parameters.AddWithValue("@text", cb_room.SelectedItem);
sqlcom.Parameters.AddWithValue("@year",klientClass.Year());
conn.Open();
result = sqlcom.ExecuteScalar().ToString(); // on this line ex occurs
conn.Close();
我得到了这个异常:
NullReferenceException: Object reference not set to an instance of an object.
有人能帮我解决这个问题吗?