连接各种数据库语句

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;
using System.Data.OleDb;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            GridView1.DataSource = sqlconn1().Tables["donkey"].DefaultView;
            GridView1.DataBind();
            GridView2.DataSource = sqlconn2();
            GridView2.DataBind();
            GridView3.DataSource = sqlaccess();
            GridView3.DataBind();
            GridView4.DataSource = sqlexcel();
            GridView4.DataBind();
        }
    }
    public DataSet sqlconn1()
    {
        SqlConnection conn = new SqlConnection("data source=(local);database=monkey;uid=monkey;pwd=donkey");
        SqlDataAdapter database = new SqlDataAdapter("select * from donkey", conn);
        DataSet ds = new DataSet();
        conn.Open();
        database.Fill(ds, "donkey");
        conn.Close();
        return ds;
    }

    public DataTable sqlconn2()
    {
        SqlConnection conn = new SqlConnection("data source=(local);database=monkey;uid=monkey;pwd=donkey");
        SqlCommand cmd = new SqlCommand("select * from houzi", conn);
        SqlDataReader sdr = null;
        conn.Open();
        sdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
        DataTable dt = new DataTable();
        dt.Load(sdr);
        return dt;
    }

    public DataSet sqlaccess()
    {
        OleDbConnection conn = new OleDbConnection("provider=Microsoft.jet.oledb.4.0;data source=" + Server.MapPath("monkey.mdb") + "");
        OleDbDataAdapter database = new OleDbDataAdapter("select * from donkey", conn);
        DataSet ds = new DataSet();
        conn.Open();
        database.Fill(ds, "donkey");
        return ds;
    }
    public DataSet sqlexcel()
    {
        OleDbConnection conn = new OleDbConnection("provider=Microsoft.jet.oledb.4.0;data source=" + Server.MapPath("book1.xls") + ";Extended Properties=Excel 8.0");
        OleDbDataAdapter database = new OleDbDataAdapter("select * from [sheet1$]", conn);
        DataSet ds = new DataSet();
        conn.Open();
        database.Fill(ds);
        conn.Close();
        return ds;
    }
}