数据联动查询界面设计之一

今天抽空做了一下数据的联动查询界面。

1.list.aspx：
放置4个Combobox控件，ID分别为：cb1,cb2,cb3,cb4

2.list.aspx.cs:
主要实现页面载入（Page_Load）、控件与数据库相应字段的绑定以及几个控件的联动（cb1_TextChanged,cb3_TextChanged）。后台代码如下：

//名称空间引用
using System;
using System.Data;
using System.Data.OleDb;
using System.Configuration;
using System.Collections;
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;

public partial class list : System.Web.UI.Page
{
    //页面载入事件
    //实现与数据库的联接、控件数据绑定初始化
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            //数据库连接字符串设置,其中MapPath()取得站点根目录所在路径.
            string strCon = "Provider=Microsoft.Jet.OleDb.4.0;";
            strCon += "Data Source=";
            strCon += MapPath("~/App_Data/db.mdb");

            OleDbConnection oleCon = new OleDbConnection(strCon);

            //设置四个控件对应的查询语句.
            string strSel = "select * from 省份";
            string strSel2 = "select * from 商业";
            string strSel3 = "select * from 地区";
            string strSel4 = "select * from 终端";

            OleDbCommand myCom = new OleDbCommand(strSel, oleCon);
            OleDbCommand myCom2 = new OleDbCommand(strSel2, oleCon);
            OleDbCommand myCom3 = new OleDbCommand(strSel3, oleCon);
            OleDbCommand myCom4 = new OleDbCommand(strSel4, oleCon);

            oleCon.Open();

            //为每个控件绑定相应数据.
            OleDbDataReader myDR = myCom.ExecuteReader();
            cb1.DataSource = myDR;
            cb1.DataTextField = "省份";
            cb1.DataBind();
            myDR.Close();

            OleDbDataReader myDR2 = myCom2.ExecuteReader();
            cb2.DataSource = myDR2;
            cb2.DataTextField = "商业名称";
            cb2.DataBind();
            myDR2.Close();

            OleDbDataReader myDR3 = myCom3.ExecuteReader();
            cb3.DataSource = myDR3;
            cb3.DataTextField = "地区名称";
            cb3.DataBind();
            myDR3.Close();

            OleDbDataReader myDR4 = myCom4.ExecuteReader();                  
            cb4.DataSource = myDR4;
            cb4.DataTextField = "终端名称";
            cb4.DataBind();                       
            myDR4.Close();

            oleCon.Close();

        }
    }

    //"省份"下拉框的文本改变事件,当省份改变时"商业"、"地区"、"终端名称"相应进行改变
    protected void cb1_TextChanged(object sender, EventArgs e)
    {
        //数据库连接字符串
        string strCon = "Provider=Microsoft.Jet.OleDb.4.0;";
        strCon += "Data Source=";
        strCon += MapPath("~/App_Data/db.mdb");
        OleDbConnection oleCon = new OleDbConnection(strCon);

        //产生联动的控件的查询代码,注意加入了对"省份"控件的文本值的引用
        string strSel = "select * from 商业 where [省份] like '"+cb1.Text + "'";
        string strSel2 = "select * from 地区 where [省份] like '" + cb1.Text + "'";
        string strSel3 = "select * from 终端 where [省份] like '" + cb1.Text + "'";

        OleDbCommand myCom = new OleDbCommand(strSel, oleCon);
        OleDbCommand myCom2 = new OleDbCommand(strSel2, oleCon);
        OleDbCommand myCom3 = new OleDbCommand(strSel3, oleCon);

        oleCon.Open();

        OleDbDataReader myDR = myCom.ExecuteReader();
        cb2.DataSource = myDR;
        cb2.DataTextField = "商业名称";
        cb2.DataBind();
        myDR.Close();

        OleDbDataReader myDR2 = myCom2.ExecuteReader();
        cb3.DataSource = myDR2;
        cb3.DataTextField = "地区名称";
        cb3.DataBind();
        myDR2.Close();

        OleDbDataReader myDR3 = myCom3.ExecuteReader();
        cb4.DataSource = myDR3;
        cb4.DataTextField = "终端名称";
        cb4.DataBind();
        myDR3.Close();

        oleCon.Close();      
    }

    //"地区"控件的文本改变事件,引起"终端"控件改变.
    protected void cb3_TextChanged(object sender, EventArgs e)
    {
        string strCon = "Provider=Microsoft.Jet.OleDb.4.0;";
        strCon += "Data Source=";
        strCon += MapPath("~/App_Data/db.mdb");
        OleDbConnection oleCon = new OleDbConnection(strCon);

        string strSel = "select * from 终端 where [省份] like '" + cb1.Text + "' and [地区] like '" + cb3.Text +"'";
        OleDbCommand myCom = new OleDbCommand(strSel, oleCon);
        oleCon.Open();
        OleDbDataReader myDR = myCom.ExecuteReader();
        cb4.DataSource = myDR;
        cb4.DataTextField = "终端名称";
        cb4.DataBind();
        myDR.Close();

        oleCon.Close();

    }
}

注意问题:
1.对名称空间的引用.
2.连接字符串中数据库文件所在路径的表示.
3.用同一连接对多个控件进行数据绑定时要注意DataReader的使用-前一个close之后才能创建第二个,否则会出错.
4.在查询语句中引用控件文本值的方式.

这次主要的收获是成功连接数据库并实现联动,代码看起来好象有点冗长,没办法,编程经验尚少,希望大侠们能多多指正!!