SqlConnection conn = new SqlConnection();
            conn = new SqlConnection("Data Source=.;Initial Catalog=kuaiji;Persist Security Info=True;User ID=sa;Password=123456");
            conn.Open();
            SqlCommand com = new SqlCommand();
            com.CommandType = CommandType.Text;
            com.CommandText = "insert into tb_shiti (kemu,if_valid) values ( '" + 1 + "','" + 1 + "')";
            com.Connection = conn;
            conn.Close();高人们帮我看看这条语句为什么插不到数据库里呀