ASP.net 控件实现数据级联

浏览数：46 / 时间：2015年06月09日

今天我们来一起用ASP.net实现一个级联，这个小不点应该是会经常用到的的。

咱们简单的画两个窗体。文本框会根据下拉框所选的内容显示不同的内容。

具体实现效果如下

步骤一：

准备工作，建立相应的数据库。

显示效果如下

附脚本如下

create database department
 
use department
 
create table TDepartment
(
 depID int primary key,
 depName varchar(30) not null
)
 
insert into TDepartment values(1,‘教务‘)
insert into TDepartment values(2,‘高校‘)
insert into TDepartment values(3,‘办公室‘)
 
create table emp
(
 
    empID int primary  key,
    empName varchar(30) not null,
    depID int foreign key references TDepartment(depID)
     
)
insert into emp values(1,‘小马‘,1)
insert into emp values(2,‘小丹‘,1)
insert into emp values(3,‘小妹‘,1)
insert into emp values(4,‘马丹妹‘,3)

步骤二：

新建项目为 ASP.ne Web 窗体应用程序。在窗体中画图中的两个控件。DropDownList 和ListBox，分别命名为 ddlDep 和lBoxEmp。同时将DropDownList中AutoPostBack属性设置为TRUE(目的是让每次重选列表能有响应)。
我们需要在formload 和ddlDep_SelectedIndexChanged 时间中编写相应的代码。其中ddlDep_SelectedIndexChanged是选中空间ddlDep在右侧属性-事件中双击时间SelectedIndexChanged

using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data.SqlClient;//数据库
 
namespace department
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.ListBox lBoxEmp;
        protected System.Web.UI.WebControls.DropDownList ddlDep;
        protected void Page_Load(object sender, EventArgs e)
        {
            if (!this.IsPostBack)
            {
 
                SqlConnection con = DBcon.createConnection();
                con.Open();
                //显示部门
                SqlCommand cmd = new SqlCommand("select * from  TDepartment", con);
                SqlDataReader sdr = cmd.ExecuteReader();
                this.ddlDep.DataSource = sdr;
                this.ddlDep.DataTextField = "depName";
                this.ddlDep.DataValueField = "depID";
                this.ddlDep.DataBind();
                sdr.Close();
                //显示员工
                SqlCommand cmdEmp = new SqlCommand("select * from emp where  depID=" + this.ddlDep.SelectedValue, con);
                SqlDataReader sdrEmp = cmdEmp.ExecuteReader(); ;
                while (sdrEmp.Read())
                {
                    this.lBoxEmp.Items.Add(new ListItem(sdrEmp.GetString(1), sdrEmp.GetInt32(0).ToString()));
 
                }
                sdrEmp.Close();
                //此处防止用户代码以初始化页面
 
                //关闭连接
                con.Close();
 
            }
        }
 
        protected void ddlDep_SelectedIndexChanged(object sender, EventArgs e)
        {
            this.lBoxEmp.Items.Clear();
 
            SqlConnection con = DBcon.createConnection();
            con.Open();           //显示员工
            SqlCommand cmdEmp = new SqlCommand("select * from emp where  depID=" + this.ddlDep.SelectedValue, con);
            SqlDataReader sdrEmp = cmdEmp.ExecuteReader(); ;
            while (sdrEmp.Read())
            {
                this.lBoxEmp.Items.Add(new ListItem(sdrEmp.GetString(1), sdrEmp.GetInt32(0).ToString()));
 
            }
            sdrEmp.Close();
            //此处防止用户代码以初始化页面
 
            //关闭连接
            con.Close();
 
        }
 
    }
}

以上是主要内容，下面把获取数据库的语句写在下面。这样便是一个完整的小功能。

using System;
using System.Data.SqlClient;
namespace department
{
    public class DBcon
    {
        public DBcon(){ }
        public static SqlConnection createConnection()
        {
            SqlConnection con = new SqlConnection("server=.;database=department;uid=sa;pwd=123456;");
            return con;
             
        }
    }
}