Filter control

using CMS.FormEngine.Web.UI;
using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Linq;
using CMS.DataEngine;
using CMS.Helpers;
using CMS.DocumentEngine.Web.UI;

public partial class CMSModules_Feldmann_Form_Controls_SearchSkuNameSkuNumberFilter : CMSAbstractQueryFilterControl
{

    /// <summary>
    /// Sets up the inner child controls.
    /// </summary>
    private void SetupControl()
    {
        // Hides the filter if StopProcessing is enabled
        if (this.StopProcessing)
        {
            this.Visible = false;
        }

        // Initializes only if the current request is NOT a postback
        else if (!RequestHelper.IsPostBack())
        {

        }
    }


    /// <summary>
    /// Generates a WHERE condition and ORDER BY clause based on the current filtering selection.
    /// </summary>
    private void SetFilter()
    {
        string where = "";
        string order = "";

        if (!string.IsNullOrWhiteSpace(tbxValue.Text))
        {
            this.WhereCondition =SqlHelper.AddWhereCondition(this.WhereCondition,  string.Format("SkuNumber like '%{0}%'", SqlHelper.EscapeQuotes(tbxValue.Text)));
        }

        // Raises the filter changed event
        this.RaiseOnFilterChanged();
    }

    /// <summary>
    /// Init event handler.
    /// </summary>
    protected override void OnInit(EventArgs e)
    {
        // Creates the child controls
        SetupControl();
        base.OnInit(e);
    }

    /// <summary>
    /// PreRender event handler
    /// </summary>
    protected override void OnPreRender(EventArgs e)
    {
        // Checks if the current request is a postback
        if (RequestHelper.IsPostBack())
        {
            // Applies the filter to the displayed data
            SetFilter();
        }

        base.OnPreRender(e);
    }
}