运行到da.Fill(data,"销售");就出现问题：参数化查询 '(@编号 char(20),@型号规格 char(20),@销售单价

protected void Button2_Click(object sender, EventArgs e)
    {
        SqlDataAdapter da = new SqlDataAdapter();
        SqlConnection conn = new SqlConnection();
        conn.ConnectionString = "Data Source=RGYJ-AVTYN682XD;Initial Catalog=库;User ID=sa;Password=sa123456789";
        SqlCommand selectCmd = new SqlCommand();
         = "SELECT * FROM 库存";
        selectCmd.Connection = conn;
        SqlCommand insertCmd = new SqlCommand();
         = "insert into 销售 values(@编号,@型号规格,@销售单价,@数量,@总价,@利润)";
        insertCmd.Connection = conn;
        insertCmd.Parameters.Add("@编号", SqlDbType.Char, 20, "编号");
        insertCmd.Parameters.Add("@型号规格", SqlDbType.Char, 20, "型号规格");
        insertCmd.Parameters.Add("@销售单价", SqlDbType.Float,10, "销售单价");
        insertCmd.Parameters.Add("@数量", SqlDbType.Int, 20, "数量");
        insertCmd.Parameters.Add("@总价", SqlDbType.Float,10, "总价");
        insertCmd.Parameters.Add("@利润", SqlDbType.Float, 10, "利润");
        da.SelectCommand = selectCmd;
        da.SelectCommand = insertCmd;
        DataSet data = new DataSet();
        da.Fill(data, "销售");
        DataRow drNew = data.Tables["销售"].NewRow();
        drNew[1] = TextBox4.Text;
        drNew[2] = TextBox5.Text;
        drNew[3] = TextBox6.Text;
        drNew[4] = TextBox7.Text;
        data.Tables["销售"].Rows.Add(drNew);
        da.Update(data, "销售");
    }

运行到da.Fill(data,"销售");就出现问题：参数化查询 '(@编号 char(20),@型号规格 char(20),@销售单价 float,@数量 int,@总价 float,@利润 f' 需要参数 @编号，但未提供该参数。求解答