Get Last 20 Slowest SQL Queries

 SELECT TOP 20
    SUBSTRING(qt.text, (qs.statement_start_offset/2)+1,
    ((CASE qs.statement_end_offset WHEN -1 THEN DATALENGTH(qt.text)
                                   ELSE qs.statement_end_offset
      END - qs.statement_start_offset)/2)+1),
    qs.execution_count,
    qs.total_logical_reads, qs.last_logical_reads,
    qs.min_logical_reads, qs.max_logical_reads,
    qs.total_elapsed_time, qs.last_elapsed_time,
    qs.min_elapsed_time, qs.max_elapsed_time,
    qs.last_execution_time,
    qp.query_plan
FROM
    sys.dm_exec_query_stats qs
CROSS APPLY
    sys.dm_exec_sql_text(qs.sql_handle) qt
CROSS APPLY
    sys.dm_exec_query_plan(qs.plan_handle) qp
WHERE
    qt.encrypted = 0
ORDER BY
    qs.total_logical_reads DESC