如何在ASP.NET中動態創建下拉控件

Question

我已經動態創建了5個下拉列表。這是從aspx.cs

for (int i = 0; i < 5; i++) 
      { 
       DropDownList drop = new DropDownList(); 
       drop.ID = "dropdownlist" + i; 
       form1.Controls.Add(drop); 
       form1.Controls.Add(new LiteralControl("<br />")); 
      } 

我已經有喜歡

if (!this.IsPostBack) 
     { 
      string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString; 
      using (SqlConnection con = new SqlConnection(constr)) 
      { 
       using (SqlCommand cmd = new SqlCommand("SELECT ID, Name FROM RejectedProduct")) 
       { 
        cmd.CommandType = CommandType.Text; 
        cmd.Connection = con; 
        con.Open(); 
        DropDownList1.DataSource = cmd.ExecuteReader(); 
        DropDownList1.DataTextField = "Name"; 
        DropDownList1.DataValueField = "ID"; 
        DropDownList1.DataBind(); 
        con.Close(); 
       } 
      } 
      DropDownList1.Items.Insert(0, new ListItem("Select Item for adding", "0"));} 

如何使用用於動態創建新的每次5下拉這段代碼另一個下拉代碼？

Answer 1

請查看Mysterio11的評論& Win。

填寫數據的基本思路如下。最重要的是它沒有優化。在循環中創建命令和連接是不同的想法。

 if (!this.IsPostBack) 
     { 
      DropDownList DropDownList1; 
      for (int i = 0; i < 5; i++) 
      { 
       DropDownList1 = (DropDownList)FindControl("dropdownlist" + i); 
       string constr = ConfigurationManager.ConnectionStrings["constr"].ConnectionString; 
       using (SqlConnection con = new SqlConnection(constr)) 
       { 
        using (SqlCommand cmd = new SqlCommand("SELECT ID, Name FROM RejectedProduct")) 
        { 
         cmd.CommandType = CommandType.Text; 
         cmd.Connection = con; 
         con.Open(); 
         DropDownList1.DataSource = cmd.ExecuteReader(); 
         DropDownList1.DataTextField = "Name"; 
         DropDownList1.DataValueField = "ID"; 
         DropDownList1.DataBind(); 
         con.Close(); 
        } 
       } 
       DropDownList1.Items.Insert(0, new ListItem("Select Item for adding", "0")); 
      } 
     }