前台： 

 function SchoolsChange()
        {
      var a="55";
        
          a=" <%=SchoolsChange()%>";
          
            alert(a);
        }

                 <dx:ASPxComboBox ID="cmbSchools" runat="server" ClientIDMode="AutoID" CssFilePath="~/App_Themes/Aqua/{0}/styles.css"
                                CssPostfix="Aqua" onkeyup="SchoolsChange()"    LoadingPanelImagePosition="Top" ShowShadow="False"   SpriteCssFilePath="~/App_Themes/Aqua/{0}/sprite.css" DropDownStyle="DropDown" OnTextChanged="cmbSchools_TextChanged" AutoPostBack="True" IncrementalFilteringMode="Contains">

protected  string   SchoolsChange(  )
        {
         
            DataView dv = new DataView();
            dv = schoolsDT.DefaultView;
            string SelectK = " sch_name like '%" + this.cmbSchools.Text.ToString().Trim() + "%' ";
            dv.RowFilter = SelectK;
            //DataRow[] rows = schoolsDT.Select(SelectK);
            //DataTable dt = dv.ToTable();
 DataTable dtn = dv.ToTable();
        
               
                this.cmbSchools.Items.Clear();

                this.cmbSchools.DataSource = dtn;
                this.cmbSchools.TextField = "sch_name";
                this.cmbSchools.ValueField = "school_id";
                this.cmbSchools.DataBind();

               return SelectK + "::::6666666::::" + schoolsDT.Rows.Count;
          

        }