从 ASP.NET 中的 DropDownList 中选择后填充多个文本框

Question

我有一个链接到 SQL 数据库的 DropDownList。它目前显示客户列表。我正在尝试这样做，以便一旦选择了客户，就会自动填充多个文本框（例如地址、城市等）。我能够自动填充“公司名称”文本框，因为该值是选定的值，但我不知道如何使用行中的其余数据填充其他文本框。我最好怎么做？

在 .aspx 中：

<asp:DropDownList ID="DropDownList1" runat="server" ></asp:DropDownList>

C#：

DataTable customers = new DataTable();
...

SqlDataAdapter adapter = new SqlDataAdapter("SELECT CustomerName FROM Customers.dbo.Customer", connection);
                adapter.Fill(customers);
                DropDownList1.DataSource = customers;
                DropDownList1.DataTextField = "CustomerName";
                DropDownList1.DataValueField = "CustomerName";
                DropDownList1.DataBind();

编辑：感谢卡尔的帮助。如果您有类似的问题，请遵循他的建议。另外，请确保更改下拉列表，使其看起来像：

<asp:DropDownList ID="DropDownList1" runat="server" AutoPostBack="true" onselectedindexchanged="CompanyChanged"></asp:DropDownList>

EDIT2：对于那些有同样问题的人。这是我的代码：

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)

    {
        LoadOptions();
    }
}
protected void LoadOptions()
    {
        DataTable customers = new DataTable();

        SqlConnection connection = new SqlConnection(INSERT YOUR CONNECTION STRING HERE);
        using (connection)
        {
            SqlDataAdapter adapter = new SqlDataAdapter("SELECT Column1 FROM Table", connection);

            adapter.Fill(customers);
            DropDownListID.DataSource = customers;

            companyselect.DataTextField = "Column1";
            companyselect.DataValueField = "Column1";
            companyselect.DataBind(); 
        }
    }

protected void SelectionChanged(object sender, EventArgs e)
    {
        string selected= DropDownListID.SelectedItem.Value;

        SqlConnection connection = new SqlConnection(YOUR CONNECTION STRING);
        using (connection)
        {

            SqlCommand command = new SqlCommand("SELECT * FROM Table WHERE Column1= @Column1", connection);
            command.Parameters.AddWithValue("@Column1", selected);
            command.CommandType = CommandType.Text;
            connection.Open();
            SqlDataReader reader = command.ExecuteReader();
            using (reader)
            {
                if (reader.HasRows)
                {
                    reader.Read();

//add as many as needed to fill your textboxes
                    TextBox1.Text = reader.GetString(1);
                    TextBox2.Text = reader.GetString(2);
                    TextBox3.Text = reader.GetString(3);
                }
                else { }
            }
        }
    }

这就是我的下拉列表的样子：

<asp:DropDownList  ID="DropDownListID" runat="server" AutoPostBack="true" onselectedindexchanged="SelectionChanged"></asp:DropDownList>

Answer 1

我强烈建议您使用数据库中的 CustomerID 或等效 ID 字段作为下拉列表中的 DataValueField，因为您可能希望在数据库中允许相同的客户名称，但能够通过 ID 将它们区分开来。

试试这个：

SqlDataAdapter adapter = new SqlDataAdapter("SELECT CustomerName, CustomerID FROM Customers.dbo.Customer", connection);
adapter.Fill(customers);
DropDownList1.DataSource = customers;
DropDownList1.DataTextField = "CustomerName";
DropDownList1.DataValueField = "CustomerID";
DropDownList1.DataBind();

注意：将 CustomerID 更改为您的数据库表中实际的 ID 列名。

现在在下拉列表的SelectedIndexChanged 事件中，获取所选项目的 ID 并在数据库中查询单行数据，如下所示：

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
    string selectedID = DropDownList1.SelectedItem.Value;

    SqlCommand theCommand = new SqlCommand("SELECT * FROM Customers.dbo.Customer WHERE CustomerID = @CustomerID", connection);
    theCommand.Paramters.AddWithValue("@CustomerID", selectedId);
    theCommand.CommandType = CommandType.Text;

    using (SqlDataReader theReader = theCommand.ExecuteReader())
    {
        if (theReader.HasRows)
        {
            // Get the first row
            theReader.Read();

            // Set the text box values
            CustomerName.Text = theReader.GetString(0);
            ...
        }
    } 
}

注意：单行客户数据的检索使用参数化查询来避免 SQL 注入漏洞。此外，上面的代码使用SqlCommand 和SqlDataReader 以及using 块来正确处理读取器对象。

Answer 2

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        try
        {
            SQLconn.Open();

            string req = "select distinct CapaciteTotal from Avion where NomAvion=" + DropDownList1.Text + "";
            SqlCommand com = new SqlCommand(req, SQLconn);
            SqlDataReader dr = com.ExecuteReader();
            if (dr.Read())
            {
                TextBox1.Text = dr.GetValue(1).ToString();
                if (DropDownList4.Text == "Aller Retour")
                {
                    TextBox2.Text = dr.GetValue(1).ToString();
                }

            }
        }
        catch(Exception ex)
        {
            HttpContext.Current.Response.Write("<script>alert('Probleme de la base de donnee : " + ex.Message + "')</script>");
        }
        finally
        {
            SQLconn.Close();
        }

    }