来自数据库的 ASP 下拉列表数据绑定答案

【问题标题】：ASP dropdownlist databind from database来自数据库的 ASP 下拉列表数据绑定
【发布时间】：2012-07-21 12:40:06
【问题描述】：

我正在使用 2 个下拉列表。国家第一，州第二。如果我从 1ft 下拉列表中选择 India，第二个会自动从数据库中自动绑定印度的所有州。

我已将country_tbl 用于国家，并与第一个下拉列表和india_tbl、us_tbl、sri_tbl 绑定用于这些国家/地区的绑定状态。

请帮助我。我该怎么办？

我的代码如下：

protected void Page_Load(object sender, EventArgs e)
{
    if (!Page.IsPostBack)
    {
        method1();
    }
}

protected void method1()
{
    string s1 = "data source=ALOK-PC\\SQLEXPRESS;database=MySite;integrated security=true";
    SqlConnection con = new SqlConnection(s1);
    string s2 = "select * from country";
    SqlCommand cmd = new SqlCommand(s2, con);
    con.Open();
    SqlDataReader dr = cmd.ExecuteReader();
    DropDownList1.DataTextField = "name";
    DropDownList1.DataValueField = "name";
    DropDownList1.DataSource = dr;
    DropDownList1.DataBind();
    con.Close();
    dr.Close();
}

protected void methodInd()
{
    string s1 = "data source=ALOK-PC\\SQLEXPRESS;database=MySite;integrated security=true";
    SqlConnection con = new SqlConnection(s1);
    string s2 = "select * from india";
    SqlCommand cmd = new SqlCommand(s2, con);
    con.Open();
    SqlDataReader dr = cmd.ExecuteReader();
    DropDownList2.DataTextField = "name";
    DropDownList2.DataValueField = "name";
    DropDownList2.DataSource = dr;
    DropDownList2.DataBind();
    con.Close();
    dr.Close();
}

protected void methodpak()
{
    string s1 = "data source=ALOK-PC\\SQLEXPRESS;database=MySite;integrated security=true";
    SqlConnection con = new SqlConnection(s1);
    string s2 = "select * from pakistan";
    SqlCommand cmd = new SqlCommand(s2, con);
    con.Open();
    SqlDataReader dr = cmd.ExecuteReader();
    DropDownList2.DataTextField = "name";
    DropDownList2.DataValueField = "name";
    DropDownList2.DataSource = dr;
    DropDownList2.DataBind();
    con.Close();
    dr.Close();
}

protected void methodsri()
{
    string s1 = "data source=ALOK-PC\\SQLEXPRESS;database=MySite;integrated security=true";
    SqlConnection con = new SqlConnection(s1);
    string s2 = "select * from srilanka";
    SqlCommand cmd = new SqlCommand(s2, con);
    con.Open();
    SqlDataReader dr = cmd.ExecuteReader();
    DropDownList2.DataTextField = "name";
    DropDownList2.DataValueField = "name";
    DropDownList2.DataSource = dr;
    DropDownList2.DataBind();
    con.Close();
    dr.Close();
}

protected void submit_Click(object sender, EventArgs e)
{

}

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
    if (DropDownList1.SelectedItem.Text=="india")
    {
        methodInd();
    }
    else if (DropDownList1.SelectedItem.Text=="pakistan")
    {
        methodpak();
    }
    else if (DropDownList1.SelectedItem.Text=="srilanka")
    {
        methodsri();
    }
}

【问题讨论】：

每个国家都有不同的表格？你确定你做对了吗？您可以将所有州保存在一个表中，并使用 CountryID 列来标识this states belongs to which country。您可以像SELECT ID,NAME FROM STATE WHERE COUNTRY_ID=theCountryId 一样查询它

标签： c# asp.net

【解决方案1】：

您的方法是错误的，您不应该为每个国家/地区的州提供单独的表格，因此您可以有一个查询和一种方法来绑定到您的州列表

将架构更改为

CREATE TABLE Country 
(
  id int,  
  country_name,
  primary key(id)
)

Country_State 
(
  id  int, 
  state_name, 
  country_id,
  primary key(id)
)

country_id 是链接回该国家/地区的外键

country
------------------------
id  Name
------------------------
1   India
2   Pakistan


country_state
-----------------------------------
id  Name              country_id
------------------------------------
1   Delhi             1
2   Bangladesh        1
3   Some Indians      1
4   S1_Pakistan       2
5   S2_Pakistan       2

您的查询

Select Id, Name from Country

Select Id, Name From country_states Where country_id = @id

只调用一种方法来绑定所有状态

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
     string country_id =  DropDownList1.SelectedValue;
     BindStatesByCountry(country_id);
}

protected void methodsri(string countryId) //change this to BindStatesByCountry
{
    string s1 = "data source=ALOK-PC\\SQLEXPRESS;database=MySite;integrated security=true";
    SqlConnection con = new SqlConnection(s1);
    con.Open();

    string s2 = "select * from country_states where country_id=@countryId";
    SqlCommand cmd = new SqlCommand(s2, con);
    cmd.Parameters.AddWithValue("@countryId", countryId);
    SqlDataReader dr = cmd.ExecuteReader();
    DropDownList2.DataTextField = "name";
    DropDownList2.DataValueField = "name";
    DropDownList2.DataSource = dr;
    DropDownList2.DataBind();
    con.Close();
    dr.Close();
}

希望对你有帮助

【讨论】：

【解决方案2】：

你想实现一个主细节模式，所以看这个网址： http://msdn.microsoft.com/en-us/library/aa581789.aspx 更喜欢存储过程而不是 sql 注入最好的尊重

【讨论】：