DropDownList控件绑定数据源的三种方法

   this.ddltype.DataTextField = "btName";//显示的值
        this.ddltype.DataValueField = "btId";//获取dropdownlist中的值
        ddltype.DataSource = service.GetBusinessTypeAll("");
        this.ddltype.DataBind();

 DataTable dt_GetBusinessName = service.GetBusinessTypeAll("");
        //表中无数据的话直接返回
        if (dt_GetBusinessName == null)
          return;
        for (int i = 0; i < dt_GetBusinessName.Rows.Count; i++)
        {
          ddltype.Items.Add(new ListItem(dt_GetBusinessName.Rows[i]["btName"].ToString().Trim(),//显示的值
          dt_GetBusinessName.Rows[i]["btId"].ToString().Trim()));
        }s
        ddltype.Items.Add(new ListItem("全部", "-1"));
        ddltype.Text = "全部";

protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
  {
    this.TextBox1.Text = this.DropDownList1.SelectedItem.Text.ToString();
  }

 protected void ddl_bumen_SelectedIndexChanged(object sender, EventArgs e)
  {
    if (this.ddl_bumen.Text != "选择部门")
    {
      int id = Int32.Parse(this.ddl_bumen.Text);
      SqlParameter bumen = new SqlParameter("@dept_id", id);
      IList<lbEmploy> list = BLLGeneric.Select<lbEmploy>(CommandType.StoredProcedure, "lb_liandong", bumen);
      //配置数据源
      this.ddl_em.DataSource = list;
      //绑定字段属性
      this.ddl_em.DataTextField = "Em_name";
      this.ddl_em.DataValueField = "Em_name";
      //绑定控件
      this.ddl_em.DataBind();
    }
    else
    {
      this.Response.Write(string.Format(GetRedirect.WINALERT, "请选择部门"));
      this.ddl_bumen.Focus();
      return;
    }
  }

SqlConnection conn = UtilitySqlClass.OperateDataBase.ReturnConn();
string strSQL = "select * from CompanyType";
SqlDataAdapter ada = new SqlDataAdapter(strSQL, conn);
DataSet ds = new DataSet();
ada.Fill(ds, "CompanyType");
DropDownList1.DataSource = ds.Tables["CompanyType"].DefaultView;
DropDownList1.DataValueField = ds.Tables["CompanyType"].Columns[1].ColumnName;
DropDownList1.DataTextField = ds.Tables["CompanyType"].Columns[1].ColumnName;
DropDownList1.DataBind();
ds.Dispose();

protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
SqlConnection conn = UtilitySqlClass.OperateDataBase.ReturnConn();
try
{
conn.Open();
this.DropDownList1.Items.Add("");
string strSQL = "select CompanyType from CompanyType";
SqlCommand com = new SqlCommand(strSQL, conn);
SqlDataReader dr = com.ExecuteReader();
while (dr.Read())
{
this.DropDownList1.Items.Add(dr["CompanyType"].ToString());
}
}
catch (Exception ex)
{
Response.Write("<scirpt>alert('" + ex.Message.ToString() + "')</script>");
}
finally
{
conn.Close();
}
}
}

 string ConnString = ConfigurationSettings.AppSettings["ConnectionString"];
     //创建一个SqlConnection
     SqlConnection Conn = new SqlConnection( ConnString );    
     string SQL_Select = "select id, ItemName from DDLItem order by id desc";
     //构造一个SqlDataAdapter
     SqlDataAdapter myAdapter = new SqlDataAdapter( SQL_Select, Conn);
     //开始读取数据
     Conn.Open();
     DataSet dataSet = new DataSet();
     myAdapter.Fill( dataSet,"Table1" );
     Conn.Close();
     //开始绑定DropDownList
     //指定DropDownList使用的数据源
     DropDownList1.DataSource = dataSet.Tables["Table1"].DefaultView;
     //指定DropDownList使用的表里的那些字段
     DropDownList1.DataTextField = "ItemName"; /https://img.qb5200.com/download-x/dropdownlist的Text的字段
     DropDownList1.DataValueField = "id";/https://img.qb5200.com/download-x/dropdownlist的Value的字段
     DropDownList1.DataBind();

con.Open();
    SqlCommand cmd = new SqlCommand(strSql,con);
    SqlDataReader dr = cmd.ExecuteReader();
    while (dr.Read())
    {   
      DropDownList1.Items.Add(new ListItem(dr["status"].ToString(), dr["status_Id"].ToString()));
    }