三级联动下拉菜单的方法

写个CS,

AJAX也可以using System;

using System.Data;

using System.Configuration;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Data.SqlClient;

/// <summary>

/// provcityservstat 的摘要说明

/// 这个类主要是用来当省／城市／服务站都是下拉进判断，省和城市教师都是autopostback

/// </summary>

public class provcityservstat

{

public DropDownList prov;

public DropDownList city;

public DropDownList servstat;

public string servstat_id;

public provcityservstat()

{

//

// TODO: 在此处添加构造函数逻辑

//

}

//绑定省的下拉

public void dataBindToProv()

{

SqlConnection con = db.createSqlConneciton();

con.Open();

SqlCommand cmd = new SqlCommand("select * from t_prov", con);

SqlDataReader sdr = cmd.ExecuteReader();

this.prov.DataSource = sdr;

this.prov.DataTextField = "prov_name";

this.prov.DataValueField = "prov_id";

this.prov.DataBind();

sdr.Close();

con.Close();

}

//绑定城市下拉

public void dataBindToCity()

{

SqlConnection con = db.createSqlConneciton();

con.Open();

SqlCommand cmd = new SqlCommand("select * from t_city where city_provid = " + this.prov.SelectedValue, con);

SqlDataReader sdr = cmd.ExecuteReader();

this.city.DataSource = sdr;

this.city.DataTextField = "city_name";

this.city.DataValueField = "city_id";

this.city.DataBind();

sdr.Close();

con.Close();

}

//绑定服务站

public void dataBindToServstat()

{

if (this.city.SelectedValue != "")

{

SqlConnection con = db.createSqlConneciton();

con.Open();

SqlCommand cmd = new SqlCommand("select * from t_servstat where servstat_cityid = " + this.city.SelectedValue, con);

SqlDataReader sdr = cmd.ExecuteReader();

this.servstat.DataSource = sdr;

this.servstat.DataTextField = "servstat_name";

this.servstat.DataValueField = "servstat_id";

this.servstat.DataBind();

sdr.Close();

con.Close();

}

else

{

this.servstat.Items.Clear();

}

}

//一般用于新增时省，城市，服务站的下拉

public void dataBindAdd()

{

dataBindToProv();

dataBindToCity();

dataBindToServstat();

}

//当省的下拉发生变化时

public void databinddropdownprov()

{

dataBindToCity();

dataBindToServstat();

}

//下面开始是用于修改的,根据已知的servstat_id得出是哪个服务站，哪个城市，哪个省

public void dataBindMod()

{

SqlConnection con = db.createSqlConneciton();

con.Open();

SqlCommand cmd = new SqlCommand("select * from t_servstat,t_city,t_prov where prov_id = city_provid and city_id = servstat_cityid and servstat_id = " + servstat_id, con);

SqlDataReader sdr = cmd.ExecuteReader();

if (sdr.Read())

{

dataBindModProv(sdr["prov_id"].ToString());

dataBindModCity(sdr["prov_id"].ToString(), sdr["city_id"].ToString());

dataBindModServstat(sdr["city_id"].ToString(), sdr["servstat_id"].ToString());

}

sdr.Close();

con.Close();

}

//绑定到修改时的省

public void dataBindModProv(string prov_id)

{

SqlConnection con = db.createSqlConneciton();

con.Open();

SqlCommand cmd = new SqlCommand("select * from t_prov", con);

SqlDataReader sdr = cmd.ExecuteReader();

this.prov.Items.Clear();

int i = 0;

while (sdr.Read())

{

this.prov.Items.Insert(i, new ListItem(sdr["prov_name"].ToString(), sdr["prov_id"].ToString()));

if (prov_id == sdr["prov_id"].ToString())

{

this.prov.Items[i].Selected = true;

}

i++;

}

sdr.Close();

con.Close();

}

//绑定到修改时的城市

public void dataBindModCity(string prov_id, string city_id)

{

SqlConnection con = db.createSqlConneciton();

con.Open();

SqlCommand cmd = new SqlCommand("select * from t_city where city_provid = " + prov_id, con);

SqlDataReader sdr = cmd.ExecuteReader();

this.city.Items.Clear();

int i = 0;

while (sdr.Read())

{

this.city.Items.Insert(i, new ListItem(sdr["city_name"].ToString(), sdr["city_id"].ToString()));

if (city_id == sdr["city_id"].ToString())

{

this.city.Items[i].Selected = true;

}

i++;

}

sdr.Close();

con.Close();

}

//绑定到修改时的服务站

public void dataBindModServstat(string city_id, string servstat_id)

{

SqlConnection con = db.createSqlConneciton();

con.Open();

SqlCommand cmd = new SqlCommand("select * from t_servstat where servstat_cityid = " + city_id, con);

SqlDataReader sdr = cmd.ExecuteReader();

this.servstat.Items.Clear();

int i = 0;

while (sdr.Read())

{

this.servstat.Items.Insert(i, new ListItem(sdr["servstat_name"].ToString(), sdr["servstat_id"].ToString()));

if (servstat_id == sdr["servstat_id"].ToString())

{

this.servstat.Items[i].Selected = true;

}

i++;

}

sdr.Close();

con.Close();

}

}

参考一下我的,我这个是三级的

注意,下拉的autopostback要先上

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