http://www.telerik.com/help/aspnet-ajax/grid-operate-with-filter-expression-manually.htm
http://www.telerik.com/community/forums/aspnet/grid/multiple-selection-for-filter-column-radgrid.aspx
Question
Answer
Unfortunately RadGrid doesn't support this feature out-of-the-box. But it can be implemented quite easy by using custom routine hooked on RadGrid's ItemCommand event to parse entered filter text and build your own filter expression.
I have attached you a basic example how this can be achieved. In attached project you have to enclose value with spaces in them with quotation marks when using between function.
Sample
http://www.telerik.com/help/aspnet-ajax/grid-custom-option-for-filtering.html
http://demos.telerik.com/aspnet-ajax/grid/examples/hierarchy/selfreferencing/defaultcs.aspx
if (Assembly.GetAssembly(typeof(ScriptManager)).FullName.IndexOf("3.5") != -1 || Assembly.GetAssembly(typeof(ScriptManager)).FullName.IndexOf("4.0") != -1)
{
RadGrid1.MasterTableView.FilterExpression = @"it[""ReportsTo""] = Convert.DBNull";
}
else
{
RadGrid1.MasterTableView.FilterExpression = "ReportsTo IS NULL";
}
XXXDateTime.ToString() >= DateTime(2012,04,03) && XXXDateTime.ToString() <= DateTime(2012,08,06)
Note:
When applying the filter expression, can you please make sure that you have disabled the linq expressions (EnableLinqExpressions="false"). Let me know if this allows the filter expression to be properly applied.(http://www.telerik.com/community/forums/aspnet-ajax/grid/how-to-set-filterexpression-manually-using-dates.aspx)