有同学问是否可以用SQL语句直接查询告警日志的内容，即创建一张包含Alert.log内容的表或视图。 实际上之前已经有人这样做了(http://t.cn/SwGvq9)，只需要运行一个存储过程即可达到目的， 这里我对原有的语句做了一些改良， 直接执行PL/SQL块即可无需创建存储过程了，而且现在支持RAC了。

--drop table alert_log_view;
--drop directory bdump;

declare
  path_bdump varchar2(4000);
  name_alert varchar2(4000);
  ins_name   varchar2(200);
begin

  select value
    into path_bdump
    from sys.v_$parameter
   where name = 'background_dump_dest';
  select 'alert_' || value || '.log'
    into name_alert
    from sys.v_$parameter
   where name = 'instance_name';

  select value
    into ins_name
    from sys.v_$parameter
   where name = 'instance_number';

  if ins_name = '0' then
    ins_name := '';
  end if;

  execute immediate 'create or replace directory bdump'||ins_name||' as ''' || path_bdump || '''';
  execute immediate 'create table ALERT_LOG_VIEW' || ins_name ||
                    '  (MSG_line varchar2(4000)   ) ' ||
                    ' organization external ' || ' (type oracle_loader ' ||
                    ' default directory bdump' || ins_name ||
                    ' access parameters ( ' ||
                    ' records delimited by newline ' || ' nobadfile ' ||
                    ' nologfile ' || ' nodiscardfile ' || ' skip 0 ' ||
                    ' READSIZE 10485760 ' || ' FIELDS LDRTRIM ' ||
                    ' REJECT ROWS WITH ALL NULL FIELDS ' ||
                    ' (MSG_LINE (1:1000) CHAR(1000)) ' || ' ) ' ||
                    ' location (''' || name_alert || ''') )' ||
                    ' reject limit unlimited ' ||
                    ' noparallel nomonitoring ';

end;
/

执行以上PL/SQL代码，会创建名为bdump$SID的目录 和ALERT_LOG_VIEW$SID的外部表(如RAC中的1号实例PROD1，则为ALERT_LOG_VIEW1,单实例single instance则为 ALERT_LOG_VIEW)， 需要时直接查询ALERT_LOG_VIEW即可，譬如要从告警信息中找出最近三天ORA-错误的记录:

col lineno noprint
col ora_error noprint
col msg_line format a132
set pages 0 lines 300 trimspool on trim on
alter session set nls_date_language = 'american';
alter session set nls_date_format='dd/mm/yyyy hh24:mi:ss';
alter session set sql_trace=false;
break on thedate
prompt
prompt ERROR IN ALERT LOG FILE - LAST 3 DAYS
prompt =====================================
select "LINENO", "THEDATE", "ORA_ERROR", "MSG_LINE"
  from (select *
          from (select lineno,
                       msg_line,
                       thedate,
                       max(case
                             when (ora_error like 'ORA-%' or
                                  ora_error like 'PLS-%') then
                              rtrim(substr(ora_error, 1, instr(ora_error, ' ') - 1),
                                    ':')
                             else
                              null
                           end) over(partition by thedate) ora_error
                  from (select lineno,
                               msg_line,
                               max(thedate) over(order by lineno) thedate,
                               lead(msg_line) over(order by lineno) ora_error
                          from (select rownum lineno,
                                       substr(msg_line, 1, 132) msg_line,
                                       case
                                         when msg_line like
                                              '___ ___ __ __:__:__ ____' then
                                          to_date(msg_line,
                                                  'Dy Mon DD hh24:mi:ss yyyy')
                                         else
                                          null
                                       end thedate
                                  from ALERT_LOG_VIEW))))
 where ora_error is not null
   and thedate >= (trunc(sysdate) - 3)
 order by thedate

示例输出

10/11/2011 03:15:49 Thu Nov 10 03:15:49 2011
                    Errors in file /s01/orabase/diag/rdbms/vprod/VPROD1/trace/VPROD1_ora_5547.trc  (incident=11105):
                    ORA-00700: soft internal error, arguments: [kgerev1], [600], [600], [700], [], [], [], [], [], [], [], []
                    Incident details in: /s01/orabase/diag/rdbms/vprod/VPROD1/incident/incdir_11105/VPROD1_ora_5547_i11105.trc
                    Errors in file /s01/orabase/diag/rdbms/vprod/VPROD1/trace/VPROD1_ora_5547.trc  (incident=11106):
                    ORA-00600: internal error code, arguments: [], [], [], [], [], [], [], [], [], [], [], []
                    Incident details in: /s01/orabase/diag/rdbms/vprod/VPROD1/incident/incdir_11106/VPROD1_ora_5547_i11106.trc
10/11/2011 03:15:52 Thu Nov 10 03:15:52 2011
                    Dumping diagnostic data in directory=[cdmp_20111110031552], requested by (instance=1, osid=5547), summary=[incident=11105].