SQL Most Slow Query

SELECT  creation_time
         ,last_execution_time
         ,total_physical_reads
         ,total_logical_reads
         ,total_logical_writes
         , execution_count
         , total_worker_time
         , total_elapsed_time
         , total_elapsed_time / execution_count avg_elapsed_time
         ,SUBSTRING(st.text, (qs.statement_start_offset/2) + 1,
         ((CASE statement_end_offset
           WHEN -1 THEN DATALENGTH(st.text)
          ELSE qs.statement_end_offset END
            - qs.statement_start_offset)/2) + 1) AS statement_text
FROM sys.dm_exec_query_stats AS qs
CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) st
ORDER BY total_elapsed_time / execution_count DESC;