绑定下拉菜单的通用方法
/// <summary>
/// 下拉菜单绑定
/// </summary>
/// <param name="ddl">下拉菜单ID</param>
/// <param name="list">数据源</param>
/// <param name="textField">文本</param>
/// <param name="valueField">值</param>
/// <param name="defaultValue">首项默认值</param>
protected void DropDownListBind(DropDownList ddl, object list , string textField, string valueField, string defaultValue)
{
ddl.DataSource = list;
ddl.DataTextField = textField;
ddl.DataValueField = valueField;
ddl.DataBind();
if (!String.IsNullOrEmpty(defaultValue))
ddl.Items.Insert(0, new ListItem(defaultValue, "0"));
}