ASP.NET 2.0中随机读取Access数据库记录


由于使用ADO访问Access数据库会有缓存,这在随机提取数据库数据时,例如:sql="select top 10 Title,objectGuid from Document Order By Rnd(id)",将得不到随机记录,下面的例子可以克服这一缺陷,实现数据库的随机读取。

C#:

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<script runat="server">

  protected void Page_Load( object sender, EventArgs e )
  ...{
    Random rnd = new Random(unchecked((int)DateTime.Now.Ticks));
    int intRandomNumber = rnd.Next();
    string ConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=|DataDirectory|        \aspxWeb.mdb;Persist Security Info=True";
    string sql = "select top 10 Title,objectGuid from Document  Order By          Rnd(" + (-1 * intRandomNumber) + "*id)";
    System.Data.OleDb.OleDbConnection cn = new System.Data.OleDb.OleDbConnection(ConnectionString);
    cn.Open();
    System.Data.OleDb.OleDbCommand cmd = new System.Data.OleDb.OleDbCommand(sql, cn);
    System.Data.OleDb.OleDbDataReader dr = c md.ExecuteReader(System.Data.CommandBehavior.CloseConnection); GridView1.DataSource = dr; GridView1.DataBind(); dr.Close(); cmd.Dispose(); cn.Dispose(); cn = null; } </script> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title>随机读取Access数据库记录</title> </head> <body> <form id="form1" runat="server"> <div> <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false"> <Columns> <asp:HyperLinkField DataNavigateUrlFields="objectGuid" HeaderText="文章" DataTextField="Title"
            DataNavigateUrlFormatString="http://dotnet.aspx.cc/article/{0}/read.aspx" />
        </Columns>
      </asp:GridView>
    </div>
  </form>
</body>
</html>

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