详细描述信息可以参考官方手册：（V$SESS_TIME_MODEL）

DB Time
Amount of elapsed time (in microseconds) spent performing Database user-level calls. This does not include the elapsed time spent on instance background processes such as PMON.
DB CPU
Amount of CPU time (in microseconds) spent on database user-level calls. This does not include the CPU time spent on instance background processes such as PMON.

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1) background elapsed time
    2) background cpu time
          3) RMAN cpu time (backup/restore)
1) DB time
    2) DB CPU
    2) connection management call elapsed time
    2) sequence load elapsed time
    2) sql execute elapsed time
    2) parse time elapsed
          3) hard parse elapsed time
                4) hard parse (sharing criteria) elapsed time
                    5) hard parse (bind mismatch) elapsed time
          3) failed parse elapsed time
                4) failed parse (out of shared memory) elapsed time
    2) PL/SQL execution elapsed time
    2) inbound PL/SQL rpc elapsed time
    2) PL/SQL compilation elapsed time
    2) Java execution elapsed time
    2) repeated bind elapsed time

DB Time	Amount of elapsed time (in microseconds) spent performing Database user-level calls. This does not include the elapsed time spent on instance background processes such as PMON.
DB CPU	Amount of CPU time (in microseconds) spent on database user-level calls. This does not include the CPU time spent on instance background processes such as PMON.

db time and db cpu