Because accessing an Access database with ADO has a cache, this will not get random records when you randomly extract database data, such as: sql= "select top Title,objectguid from Document ORDER by Rnd (ID)." The following example can overcome this shortcoming and realize random reading of the database.
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 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 = cmd. ExecuteReader (System.Data.CommandBehavior.CloseConnection);
Gridview1.datasource = Dr;
Gridview1.databind ();
Dr. Close ();
Cmd. Dispose ();
cn. Dispose ();
cn = NULL;
}
</script>
<title> randomly read Access database records </title>
<body>
<form id= "Form1" runat= "Server" >
<div>
<asp:gridview id= "GridView1" runat= "Server" autogeneratecolumns= "false" >
<Columns>
<asp:hyperlinkfield datanavigateurlfields= "ObjectGuid" headertext= "article" datatextfield= "Title"
datanavigateurlformatstring= "Http://dotnet.aspx.cc/article/{0}/read.aspx"/>
</Columns>
</asp:GridView>
</div>
</form>
</body>
VB. NET:
<%@ Page language= "VB" debug= "true"%>
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
<script runat= "Server" >
Protected Sub Page_Load (ByVal sender as Object, ByVal e as System.EventArgs)
Dim timestring as String = DateTime.Now.Ticks.ToString ()
Dim A as UInt32 = Uint32.parse (timestring.substring (timestring.length-8, 8))
Dim B as Int32 = Bitconverter.toint32 (Bitconverter.getbytes (a), 0)
Dim rnd as Random = New Random (b)
Dim Intrandomnumber as Integer = rnd. Next
Response.Write (Intrandomnumber)
Dim ConnectionString as String = "Provider=Microsoft.Jet.OLEDB.4.0;Data source= datadirectory aspxweb.mdb;" Persist Security Info=true "
Dim SQL as String = "SELECT top Title,objectguid from Document order by Rnd (" + ( -1 * intrandomnumber). ToString () + "*id"
Dim cn as System.Data.OleDb.OleDbConnection = New System.Data.OleDb.OleDbConnection
(ConnectionString)
cn. Open ()
Dim cmd as System.Data.OleDb.OleDbCommand = New System.Data.OleDb.OleDbCommand (SQL, CN)
Dim dr as System.Data.OleDb.OleDbDataReader = cmd. ExecuteReader (System.Data.CommandBehavior.CloseConnection)
Gridview1.datasource = Dr
Gridview1.databind ()
Dr. Close ()
Cmd. Dispose ()
cn. Dispose ()
cn = Nothing
End Sub
</script>
<title> randomly read Access database records </title>
<body>
<form id= "Form1" runat= "Server" >
<div>
<asp:gridview id= "GridView1" runat= "Server" autogeneratecolumns= "false" >
<Columns>
<asp:hyperlinkfield datanavigateurlfields= "ObjectGuid" headertext= "article" datatextfield= "Title"
datanavigateurlformatstring= "Http://dotnet.aspx.cc/article/{0}/read.aspx"/>
</Columns>
</asp:GridView>
</div>
</form>
</body>
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