下拉列表选定项目

Question

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。我用数据库中的数据填充下拉列表没有问题。但是，当我选择一些项目时，它不会显示详细信息。

在我的表示层中，当下拉列表项被选中时：

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，我获取了选定的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，我已经测试了 SQL 语句。它给了我我想要的东西。但它不会显示在网页中。

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;
    }

我在另一个单独的类中执行 Reader 方法：

 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？

提前致谢。

Answer 1

你发现了你的错误，但是为了避免 Sql Injection，修改你的代码如下：

    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);