ajaxToolkit:AutoCompleteExtender

 http://moosdau.blog.163.com/blog/static/43711282008824113942459/

 

 <asp:TextBox ID="txt_tag1" runat="server"></asp:TextBox>
                        <asp:ScriptManager runat="server" ID="ScriptManager1" />
                        <ajaxToolkit:AutoCompleteExtender ID="ac1" runat="server" TargetControlID="txt_tag1" ServicePath="webservice.asmx" ServiceMethod="GetData" MinimumPrefixLength="1" CompletionSetCount=30 >
                        </ajaxToolkit:AutoCompleteExtender>

 

 public string[] GetData(string prefixText, int count)
    {
        string strconn = System.Configuration.ConfigurationManager.AppSettings["Main.ConnectionString"].Trim() + " ; Provider=SQLOLEDB;";
        OleDbConnection cnn = new OleDbConnection(strconn);
        string sql = "select top " + count.ToString() + " TagName from JackDonkey_Tag where TagName like '" + prefixText + "%' order by TagName"; 

                   //select top 30 TagName from JackDonkey_Tag where TagName like 't%' order by TagName
       

       cnn.Open();
        OleDbCommand cmd = new OleDbCommand(sql, cnn);
        List<string> suggestions = new List<string>();
        var dr = cmd.ExecuteReader();
        while (dr.Read())
        {
            suggestions.Add(dr[0].ToString());
        }
        dr.Close();
        cnn.Close();
        return suggestions.ToArray();

           }