《ASP.NET》数据绑定—DropDownList、ListBox的图文代码详解

<span style="font-family:KaiTi_GB2312;font-size:18px;">        
protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack )  //判断页面是否第一次加载
            {
                SqlConnection con = DB.createConnection();  //此方法在上一篇文章中已经介绍，调用一个已经编写好的创建数据库连接的方法。
                SqlCommand cmd = new SqlCommand("select * from province",con);
                SqlDataReader sdr = cmd.ExecuteReader();
                this.DropDownList1.DataTextField = "proName";
                this.DropDownList1.DataValueField = "proID";      //主键字段
                this.DropDownList1.DataSource = sdr;
                this.DropDownList1.DataBind();
                sdr.Close();

            }

        }</span>

<span style="font-family:KaiTi_GB2312;font-size:18px;">      
 protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
        {
            this.ListBox1.Items.Clear();
            SqlConnection con2 = DB.createConnection();
            SqlCommand cmd1 = new SqlCommand("select * from city where proID=" + this.DropDownList1.SelectedValue, con2);
            SqlDataReader sdr1 = cmd1.ExecuteReader();
            while (sdr1.Read())
            {
                this.ListBox1.Items.Add(new ListItem(sdr1.GetString(2),sdr1.GetInt32(0).ToString()));
            }
        }</span>