%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

center>
h2>font face="宋体">访问数据库的通用代码实例/font>
/h2>
/center>
body>
    form id="form1" runat="server">
    div>

    font face="宋体">
p align="center">1.请输入相应数据库连接字符串/p>
p align="center">
asp:TextBox id="ConnStrTextBox" runat="server" Width="600">/asp:TextBox>
/p>
p align="center">2.请输入相应SQL查询命令语句/p>
p align="center">
asp:TextBox id="SqlTextTextBox" runat="server" Width="600">/asp:TextBox>
/p>
p align="center">3.请选择所连接的数据库类型/p>
p align="center">
    asp:DropDownList ID="DBDropDownList" runat="server" Width="204px">
        asp:ListItem Selected="True">Access/asp:ListItem>
        asp:ListItem>SQLServer/asp:ListItem>
        asp:ListItem>Oracle/asp:ListItem>
        asp:ListItem>DB2/asp:ListItem>
    /asp:DropDownList>
/p>
p align="center">

asp:Button ID="Button1" runat="server" onclick="Button1_Click"  Text="通用数据库连接代码测试" />

/p>
p align="center">
asp:Label id="lblMessage" runat="server" Font-Bold="True" ForeColor="Red">/asp:Label>
/p>
    /form>
/font>
/div>

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        //通用数据库连接代码，这里以连接Access数据库为测试示例
        if (!IsPostBack)
        {
           ConnStrTextBox.Text = "Provider=Microsoft.Jet.OLEDB.4.0; Data source=" + Server.MapPath("User.mdb");
           SqlTextTextBox.Text = "Select COUNT(*) From Info Where Name='小顾'";
            lblMessage.Text = "";
        }
    }
    protected void Button1_Click(object sender, EventArgs e)
    {

        //定义数据库连接字符串
        string MyConnectionString = this.ConnStrTextBox.Text;
        //定义查询操作的SQL语句
        string MySQL = this.SqlTextTextBox.Text;
        //定义所要连接的数据库类型为Access
        string MyType = this.DBDropDownList.SelectedValue;
        System.Data.IDbConnection MyConnection = null;
        // 根据数据库类型，创建相应的 Connection 对象
        switch (MyType)
        {
            //选择的数据库类型为“SQLServer”，创建SqlConnection类数据库连接对象
            case "SQLServer":
                MyConnection = new System.Data.SqlClient.SqlConnection(MyConnectionString);
                break;
            case "Oracle":
                MyConnection = new System.Data.OracleClient.OracleConnection(MyConnectionString);
                break;
            //选择的数据库类型为“Access”，创建OleDbConnection类数据库连接对象
            case "Access":
                MyConnection = new System.Data.OleDb.OleDbConnection(MyConnectionString);
                break;
            //选择的数据库类型为“DB2”，创建OleDbConnection类数据库连接对象
            case "DB2":
                MyConnection = new System.Data.Odbc.OdbcConnection(MyConnectionString);
                break;
            default:
                MyConnection = new System.Data.OleDb.OleDbConnection(MyConnectionString);
                break;
        }
        Execute(MyConnection, MySQL);
    }
    public void Execute(System.Data.IDbConnection MyConnection, string strquery)
    {
        //使用 CreateCommand() 方法生成 Command 对象
        System.Data.IDbCommand MyCommand = MyConnection.CreateCommand();
        //执行定义的SQL查询语句
        MyCommand.CommandText = strquery;
        try
        {
            //打开数据库连接
            MyConnection.Open();
            //定义查询的结果信息
            String MyInfo = "测试连接成功！符合查询要求的记录共有：" + MyCommand.ExecuteScalar().ToString() + "条！";
            //输出查询结果信息
            lblMessage.Text = MyInfo;
        }
        catch (Exception ex)
        {
            //输出错误异常
            Response.Write(ex.ToString());
        }
        finally
        {
            //关闭数据库连接
            MyConnection.Close();
        }
    }
}

//选择的数据库类型为“SQLServer”，创建SqlConnection类数据库连接对象
case "SQLServer":
           MyConnection = new System.Data.SqlClient.SqlConnection(MyConnectionString);
                break;
case "Oracle":
           MyConnection = new System.Data.OracleClient.OracleConnection(MyConnectionString);
                break;
            //选择的数据库类型为“Access”，创建OleDbConnection类数据库连接对象
case "Access":
           MyConnection = new System.Data.OleDb.OleDbConnection(MyConnectionString);
                break;
            //选择的数据库类型为“DB2”，创建OleDbConnection类数据库连接对象
case "DB2":
           MyConnection = new System.Data.Odbc.OdbcConnection(MyConnectionString);
                break;
default:
            MyConnection = new System.Data.OleDb.OleDbConnection(MyConnectionString);
                break;