可以使用客户端脚本JS来提高效率

DataTextField 与 DataValueField 的区别

事件 : SelectedIndexChangedAUTOPOSTBACK 属性 TRUE （不宜多用 占资源）不用AUTOPOSTBACK

TIPS ：

con.Close();

sdrSmallclass.Close();

this.smallclass.DataBind();

this.smallclass.DataValueField = "SmallclassID";

this.smallclass.DataTextField = "SmallclassName";

SqlDataReader sdrSmall this.smallclass.DataSource = sdrSmallclass;

SqlCommand cmdSmall SqlCommand("select * from Smallclass where bigclassid=" + this.bigclass.SelectedValue, con);

con.Open();

SqlConnection con = DBCon.createconnection();

protected void bigclass_SelectedIndexChanged(object sender, EventArgs e)

//DropDownList事件

con.Close();

sdrSmallclass.Close();

this.smallclass.DataBind();

this.smallclass.DataValueField = "SmallclassID";

this.smallclass.DataTextField = "SmallclassName";

SqlDataReader sdrSmall this.smallclass.DataSource = sdrSmallclass;

SqlCommand cmdSmall SqlCommand("select * from Smallclass where bigclassid="+this.bigclass.SelectedValue,con);

//看着DropDownList绑定Smallclass

sdrBigclass.Close();

this.bigclass.DataBind();

this.bigclass.DataValueField="bigclassID";

this.bigclass.DataTextField="bigclassName";

SqlDataReader sdrBig this.bigclass.DataSource = sdrBigclass;

SqlCommand cmdBig SqlCommand("select * from Bigclass",con);

//绑定Bigclass

con.Open();

SqlConnection con = DBCon.createconnection();

if (!this.IsPostBack)

protected void Page_Load(object sender, EventArgs e)

public partial class _Default : System.Web.UI.Page

using System.Data.SqlClient;

using System.Web.UI.HtmlControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.WebControls;

using System.Web.UI;

using System.Web.Security;

using System.Web;

using System.Configuration;

using System.Data;

using System;

webform.aspx.cs

return con;

SqlConnection con = new SqlConnection("server=.;database=shop;uid=sa;pwd=");

public static SqlConnection createconnection()

// TODO: 其实System在此处添加构造函数逻辑

public DBCon()

public class DBCon

/// </summary>

/// DBCon

/// <summary>

using System.Data.SqlClient;

using System.Web.UI.HtmlControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.WebControls;

using System.Web.UI;

using System.Web.Security;

using System.Web;

using System.Configuration;

using System.Data;

using System;

DBCon.CS

</form>

</asp:DropDownList></div>

<asp:DropDownList ID="smallclass" runat="server">

</asp:DropDownList>

<asp:DropDownList ID="bigclass" runat="server" AutoPostBack="True" OnSelectedIndexChanged="bigclass_SelectedIndexChanged">

<div>

<form id="form1" runat="server">

webform.aspx

select * from Smallclass

insert into Smallclass values(8,'相比看实现2级联动using凡客成品',4)

insert into Smallclass values(7,'古龙香水',3)

insert into Smallclass values(6,'雅姿',3)

insert into Smallclass values(5,'洗面奶',3)

insert into Smallclass values(4,'TCL',2)

insert into Smallclass values(3,'SONY',2)

insert into Smallclass values(2,'其实实现吸尘器',1)

insert into Smallclass values(1,'空调',1)

bigclassid int foreign key references Bigclass(bigclassid) not null

smallclassname varchar (50) not null,

smallclassid int primary key,

create table Smallclass

select * from bigclass

insert into bigclass values(4,'相比看联动衬衫')

insert into bigclass values(3,'化妆品')

insert into bigclass values(2,'手机')

insert into bigclass values(1,'电器')

bigclassname varchar(50) not null

bigclassid int primary key,

create table Bigclass

use shop

create database shop

DataBase