C# 下拉列表所选项目

我正在尝试从下拉列表中选择动态数据并查看所选项目的详细信息。我可以用数据库中的数据填充下拉列表。但是，当我选择一些项目时，它不会显示详细信息

在“我的演示”层中，选择下拉列表项时：

protected void ddlScheduleList_SelectedIndexChanged(object sender, EventArgs e)
    {
        string address = ddlScheduleList.SelectedItem.ToString();

        Distribution scheduledIndv = new Distribution();

        scheduledIndv = packBLL.getDistributionDetail(address);

        if (scheduledIndv == null)
        {
            Console.Out.WriteLine("Null");
        }
        else
        {
            tbScheduleDate.Text = scheduledIndv.packingDate.ToString();
            tbBeneficiary.Text = scheduledIndv.beneficiary;
        }

    }

在我的业务逻辑层中，我获取所选地址并将其传递给数据访问层：

public Distribution getDistributionDetail(string address)
    {
        Distribution scheduledIndv = new Distribution();

        return scheduledIndv.getDistributionDetail(address);
    }

在我的数据访问层中，我已经测试了SQL语句。它给了我想要的。但它不会出现在网页上

public Distribution getDistributionDetail(string address)
    {
        Distribution distributionFound = null;

        using (var connection = new SqlConnection(FoodBankDB.GetConnectionString())) // get your connection string from the other class here
        {
            SqlCommand command = new SqlCommand("SELECT d.packingDate, b.name FROM dbo.Distributions d " +
            " INNER JOIN dbo.Beneficiaries b ON d.beneficiary = b.id " +
            " WHERE b.addressLineOne = '" + address + "'", connection);
            connection.Open();

            using (var dr = command.ExecuteReader())
            {
                if (dr.Read())
                {
                    DateTime packingDate = DateTime.Parse(dr["packingDate"].ToString());
                    string beneficiary = dr["beneficiary"].ToString();

                    distributionFound = new Distribution(packingDate, beneficiary);
                }
            }
        }
        return distributionFound;
    }

我的execute Reader方法位于另一个单独的类中：

 public static string connectionString = Properties.Settings.Default.connectionString;

    public static string GetConnectionString()
    {
        return connectionString;
    }

public static SqlDataReader executeReader(string query)
    {
        SqlDataReader result = null;

        System.Diagnostics.Debug.WriteLine("FoodBankDB executeReader: " + query);

        SqlConnection connection = new SqlConnection(connectionString);
        SqlCommand command = new SqlCommand(query, connection);
        connection.Open();
        result = command.ExecuteReader();
        connection.Close();

        return result;
    }

我想知道出了什么问题。是关于（！IsPostBack）还是

---

提前感谢。

您发现了错误，但为了避免Sql注入，请按如下方式修改代码：

    SqlCommand command = new SqlCommand("SELECT d.packingDate, b.name FROM dbo.Distributions d " +
                " INNER JOIN dbo.Beneficiaries b ON d.beneficiary = b.id " +
                " WHERE b.addressLineOne = @address", connection);

    command.Parameters.AddWithValue("@address", address);

---

我相信你需要让它发回以填充它。或者将它绑定到数据库。我已经发现我的错误了。我忘了在下拉列表中启用post。谢谢您存在SQL注入漏洞。SQL注入有什么负面影响？通过SQL注入，攻击者可以访问存储在SQL数据库中的所有数据。如果SQL server配置不正确，则可能执行任意代码执行。