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The author:(作者)delvpublished in(发表于) 2014/1/16 9:27:39 ASP.NET,2.0中随机读取Access数据库记录_[Asp.Net教程]
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#" %>
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 = cmd.ExecuteReader(System.Data.CommandBehavior.CloseConnection); GridView1.DataSource = dr; GridView1.DataBind(); dr.Close(); cmd.Dispose(); cn.Dispose(); cn = null;
}
随机读取Access数据库记录 DataNavigateUrlFormatString="http://dotnet.aspx.cc/article/{0}/read.aspx" />
VB.NET:
<%@ Page Language="VB" Debug="true" %>
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 10 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
来源:孟宪会之精彩世界
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