Based on this answer , I gave a related question , I would suggest the following query
SPListItem lastItem; try { using (SPSite objSite = new SPSite(sSiteUrl)) { using (SPWeb objWeb = objSite.OpenWeb()) { SPList objList = objWeb.Lists["MainHeads"]; SPQuery objQuery = new SPQuery(); objQuery.Query = "<OrderBy><FieldRef Name='HeadID' Ascending='False' /></OrderBy><RowLimit>1</RowLimit>"; objQuery.Folder = objList.RootFolder;
This assumes that you are doing CAML in code. IF not, see F. Aquino answer .
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