select * from

(select to_char(SAMPLE_TIMESTAMP_UTC,'yyyy/mm/dd hh24:mi') mi,avg(PARAMETER_VALUE) cpu7 from SANDBOXUSER.BMC_CPU

where to_char(SAMPLE_TIMESTAMP_UTC,'yyyy/mm/dd hh24:mi') BETWEEN TO_CHAR ( trunc(SYSDATE - 18), 'yyyy/mm/dd hh24:mi' )

AND TO_CHAR ( trunc(SYSDATE - 17), 'yyyy/mm/dd hh24:mi' )

group by to_char(SAMPLE_TIMESTAMP_UTC,'yyyy/mm/dd hh24:mi')

order by to_char(SAMPLE_TIMESTAMP_UTC,'yyyy/mm/dd hh24:mi'))

where  mi like TO_CHAR(trunc(SYSDATE - 18),'yyyy/mm/dd')||'%'//这是一个知识点