Sharepoint Custom Search Coding

using Microsoft.Office.Server.Administration;
using Microsoft.Office.Server.Search;
using Microsoft.Office.Server.Search.Query;


        public DataSet getSearchResults(string strSqlString)
        {
            DataSet dsResults = null;
            string strSiteUrl = ConfigurationManager.AppSettings["siteId"].ToString();
            try
            {
                SPSecurity.RunWithElevatedPrivileges(delegate()
                {
                    using (SPSite site = new SPSite(strSiteUrl))
                    {
                        FullTextSqlQuery query = new FullTextSqlQuery(site);
                        query.QueryText = strSqlString;
                        query.RowLimit = 30000;
                        query.ResultTypes = ResultType.RelevantResults;
                        ResultTableCollection coll = query.Execute();

                        if ((int)ResultType.RelevantResults != 0)
                        {
                            ResultTable tblResult = coll[ResultType.RelevantResults];
                            if (tblResult.TotalRows > 0)
                            {
                                DataTable dtResults = new DataTable("tblResults");
                                dsResults = new DataSet();
                                dsResults.Tables.Add(dtResults);
                                dsResults.Load(coll[ResultType.RelevantResults], LoadOption.OverwriteChanges, dtResults);
                            }
                        }
                    }
                });
            }
            catch (Exception ex)
            {
                throw ex;
            }
            return dsResults;
        }