title: filter a datatable/dataset based on textbox values
body: <pre><code>protected void Page_Load(object sender, EventArgs e)
  {
  
              string StartDate = Date3.Text;
              string Enddate = Date4.Text;
  
      ds = objBLL.GetUser(ItemType, ItemStatus);
                              dt = ds.Tables[0];
                              if (StartDate != null)
                              {
                                Filter records from datatable dt in such a way that
                                ParticipationStartDate &gt; startDate");
                              }
                              if (Enddate != null)
                              {
                                Filter records from datatable dt in such a way that
                                 ParticipationEndDate  &lt; EndDate
                              }
                              if(StartDate!=null &amp;&amp; Enddate!= null)
                               {
                                 i need to filter records from datatable such that 
                                 ParticipationStartDate  &gt; StartDate
                                 and ParticipationEndDate  &lt; EndDate
                               }
  
  
  
  }
                              GridView1.DataSource = dt;  dt is the filtered datatable
                              GridView1.DataBind();
                      }
  </code></pre>
  
  <p>ParticipationStartDate,ParticipationEndDate is a column in the datatable.
      startdate and enddate are textbox fields in the aspx. 
      So this is what I am trying to do. 
      If the startdate(date3.text) is not null, then datatable should give the records such that ParticipationStartDate > startdate
      If the enddate(date4.text) is not null, then datatable should give the records such that ParticipationEndDate &lt; enddate</p>