Server Error in '/' Application.

There is no row at position 0.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.IndexOutOfRangeException: There is no row at position 0.

Source Error:

Line 135:    {
Line 136:        DataSet part1 = DbHelperOleDb.Query("select * from Categories where LinkUrl='" + LinkUrl + "' and isshow=true");
Line 137:        string lft = part1.Tables[0].Rows[0]["Lft"].ToString();
Line 138:        string rgt = part1.Tables[0].Rows[0]["Rgt"].ToString();
Line 139:        DataSet part2 = DbHelperOleDb.Query("select * from Categories where Lft<" + lft + " and Rgt>" + rgt + " and isshow=true order by Lft");

Source File: d:\vhostroot\localuser\cnkb8\www\controls\part_name_more.ascx.cs    Line: 137

Stack Trace:

[IndexOutOfRangeException: There is no row at position 0.]
   System.Data.RBTree`1.GetNodeByIndex(Int32 userIndex) +2129972
   System.Data.DataRowCollection.get_Item(Int32 index) +22
   cn_controls_part_name_more.init2(String LinkUrl) in d:\vhostroot\localuser\cnkb8\www\controls\part_name_more.ascx.cs:137
   cn_controls_part_name_more.Page_Load(Object sender, EventArgs e) in d:\vhostroot\localuser\cnkb8\www\controls\part_name_more.ascx.cs:105
   System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +52
   System.Web.UI.Control.OnLoad(EventArgs e) +97
   System.Web.UI.Control.LoadRecursive() +61
   System.Web.UI.Control.LoadRecursive() +134
   System.Web.UI.Control.LoadRecursive() +134
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +693

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.8.4110.0