下拉列表綁定及修改

 一、DropDownList:
1、選項值保存到數據庫：
   Hashtable ht=new Hashtable();//這裏用Hashtable
   ht.Add("字段名"，DropDownListID.SelectedItem.Text.ToString());//保存選項Text
   ht.Add("字段名"，DropDownListID.SelectedItem.Value.ToString());//保存選項Value

2、選項值由數據庫綁定到DropDownList：
   首先DropDownListID.ClearSelection();//清除選項
    DropDownListID.Items.FindByText(dr["字段名"].ToString()).Selected = true;//選項Text
    DropDownListID.Items.FindByValue(dr["字段名"].ToString()).Selected = true;//選項Value

二、RadioButtonList:
1、選項值保存到數據庫(同DropDownList)：
   Hashtable ht=new Hashtable();//這裏用Hashtable
   ht.Add("字段名"，RadioButtonListID.SelectedItem.Text.ToString());//保存選項Text
   ht.Add("字段名"，RadioButtonListID.SelectedItem.Value.ToString());//保存選項Value

2、選項值由數據庫綁定到RadioButtonList
   string SelectItem = dr["字段名"].ToString();//將數據庫中的選項值從DataRow中讀出賦給變量SelectItem
   for (int i = 0; i < RadioButtonListID.Items.Count; i++)
   {//用for循環判斷那項被選種
       if (RadioButtonListID.Items[i].Text == SelectItem)RadioButtonListID.Items[i].Selected = true;
   }

三、CheckBoxList:
1、選項值保存到數據庫
   string SelectItem = "";//聲明一個變量來接受選項
   for (int i = 0; i < CheckBoxListID.Items.Count; i++)
   {//用for循環將所有選項用","隔開連接起來
        if (CheckBoxListID.Items[i].Selected)
        {
            SelectItem = SelectItem + CheckBoxListID.Items[i].Value + ",";//選項後加","隔開
        }
   }
   ht.Add("字段名",SelectItem.ToString());

2、選項值由數據庫綁定到CheckBoxList
   string SelectItem = dr["字段名"].ToString();
   string[] arrStr = SelectItem.Split(',');//字段是以","隔開
   foreach (string str in arrStr)
   {
       for (int i = 0; i <CheckBoxListID.Items.Count; i++)
       {
          if (this.CheckBoxListID.Items[i].Value == str)
          {
             this.CheckBoxListID.Items[i].Selected = true;
          }
       }
   }
=================================================
1.把數據綁定到CheckBoxList中

  protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                SqlConnection con = GetDBCon.GetCon();
                con.Open();
                SqlDataAdapter sda = new SqlDataAdapter("select * from admin", con);
                DataSet ds = new DataSet();
                sda.Fill(ds,"admin");
                this.CheckBoxList1.DataSource = ds.Tables[0];
                this.CheckBoxList1.DataTextField = "username";//綁定的字段名
                this.CheckBoxList1.DataValueField = "userid";//綁定的值
                this.CheckBoxList1.DataBind();
              
            
               
            }
        }

2.循環讀取出來

 protected void CheckBoxList1_SelectedIndexChanged(object sender, EventArgs e)
        {
            this.Lab2.Text = "";
            for (int i = 0; i < CheckBoxList1.Items.Count; i++)
            {
                if (this.CheckBoxList1.Items[i].Selected)
                {
                    this.Lab2.Text = this.Lab2.Text+CheckBoxList1.Items[i].Text+".";
                }
            }
        }