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Oracle System Event Triggers
Version 11.1
You may also want to view the page on Table Triggers
General
Data Dictionary Objects
dba_triggers all_triggers user_triggers trigger$
Related System Privileges administer database trigger
alter any trigger
create trigger
create any trigger
drop any trigger

System Event Trigger Types
AFTER STARTUP
BEFORE SHUTDOWN

AFTER LOGON
BEFORE LOGOFF

AFTER DB_ROLE_CHANGE -- for Data Guard failover and switchover
AFTER SUSPEND
AFTER SERVERERROR (does not trap ...
  • ORA-01403: no data found (this is in the Oracle docs but does not seem to be correct)
  • ORA-01422: exact fetch returns more than requested number of rows
  • ORA-01034: ORACLE not available
  • ORA-04030: out of process memory when trying to allocate string bytes (string, string)
Database Level Event Triggers SELECT a.obj#, a.sys_evts, b.name
FROM trigger$ a,obj$ b
WHERE a.sys_evts > 0
AND a.obj#=b.obj#
AND baseobject = 0;
Schema Level Event Triggers SELECT a.obj#, a.sys_evts, b.name
FROM trigger$ a,obj$ b
WHERE a.sys_evts > 0
AND a.obj#=b.obj#
AND baseobject = 88;

Disabling System Triggers
Sometimes you may need to disable a trigger. For example, if there is an error in a system trigger (for example an AFTER STARTUP trigger) it may be impossible to start the database. The solution is to disable the system trigger while the issue is resolved.
Or you may have a DDL trigger defined to trap all the structural changes in the production database. This trigger prevents the creation of temporary tablespace, so you would need to disable that trigger before proceeding. The following is the method for disabling system triggers.
/ as sysdba

set linesize 150
col NAME format a30
col VALUE format a20
col DESCRIPTION format a60

SELECT x.ksppinm NAME, y.ksppstvl VALUE, ksppdesc DESCRIPTION
FROM x$ksppi x, x$ksppcv y
WHERE x.inst_id = userenv('Instance')
AND y.inst_id = userenv('Instance')
AND x.indx = y.indx
AND x.ksppinm = '_system_trig_enabled';

ALTER SYSTEM SET "_system_trig_enabled" = FALSE SCOPE=BOTH;
 
Create SYSTEM EVENT TRIGGER

System Trigger Demo

Demo table and the logproc procedure  (below) must be built before the trigger will compile
CREATE OR REPLACE TRIGGER <trigger_name>
<trigger_type> ON DATABASE
CALL <procedure_name>
/
CREATE TABLE connection_audit (
login_date DATE,
user_name  VARCHAR2(30));

CREATE OR REPLACE PROCEDURE logproc IS
BEGIN
  INSERT INTO connection_audit
  (login_date, user_name)
  VALUES
  (SYSDATE, USER);
END logproc;
/


CREATE OR REPLACE TRIGGER logintrig
AFTER LOGON ON DATABASE
CALL logproc
/

conn sh/sh
conn scott/tiger
conn uwclass/uwclass

SELECT *
FROM connection_audit;

drop trigger logintrig;

Demo Application To Log Logon Attempts ... Both Successful And Failed
CREATE OR REPLACE TRIGGER <trigger_name>
<trigger_type> ON DATABASE
  <trigger_code>
END <trigger_name>;
/
truncate table connection_audit;

-- trigger to trap successful logons
CREATE OR REPLACE TRIGGER logon_audit
AFTER LOGON ON DATABASE
BEGIN
  INSERT INTO connection_audit
  (login_date, user_name)
  VALUES
  (SYSDATE, USER);
END logon_audit;
/

conn scott/tiger
conn sh/sh
conn / as sysdba
conn uwclass/uwclass

SELECT *
FROM connection_audit;

-- trigger to trap unsuccessful logons
CREATE OR REPLACE TRIGGER logon_failures
AFTER SERVERERROR
ON DATABASE

BEGIN
  IF (IS_SERVERERROR(1017)) THEN
    INSERT INTO connection_audit
    (login_date, user_name)
    VALUES
    (SYSDATE, 'ORA-1017');
  END IF;
END logon_failures;
/

conn scott/tigre
conn abc/def
conn test/test

conn uwclass/uwclass

SELECT *
FROM connection_audit;

/* 
other errors that could be trapped include:
ORA-01004 - default username feature not supported
ORA-01005 - null password given
ORA-01035 - Oracle only available to users with restricted session priv
ORA-01045 - create session privilege not granted
*/

Demo To Log System Errors
CREATE TABLE servererror_log (
error_datetime  TIMESTAMP,
error_user      VARCHAR2(30),
db_name         VARCHAR2(9),
error_stack     VARCHAR2(2000),
captured_sql    VARCHAR2(1000));

CREATE OR REPLACE TRIGGER log_server_errors
AFTER SERVERERROR
ON DATABASE
DECLARE
 captured_sql VARCHAR2(1000);
BEGIN
  SELECT q.sql_text
  INTO captured_sql
  FROM gv$sql q, gv$sql_cursor c, gv$session s
  WHERE s.audsid = audsid
  AND s.prev_sql_addr = q.address
  AND q.address = c.parent_handle;

  INSERT INTO servererror_log
  (error_datetime, error_user, db_name,
   error_stack, captured_sql)
  VALUES
  (systimestamp, sys.login_user, sys.database_name,
  dbms_utility.format_error_stack, captured_sql);
END log_server_errors;
/

After Logon Trigger for Tracing
CREATE OR REPLACE TRIGGER trace_trig
AFTER LOGON
ON DATABASE
DECLARE
 sqlstr VARCHAR2(200) := 'ALTER SESSION SET EVENTS ''10046 TRACE NAME CONTEXT FOREVER, LEVEL 4''';
BEGIN
  IF (USER = 'UWCLASS') THEN
    execute immediate sqlstr;
  END IF;
END trace_trig;
/

After Logon Trigger for Outlines
CREATE OR REPLACE TRIGGER trace_trig
AFTER LOGON
ON DATABASE
DECLARE
 sqlstr VARCHAR2(200) := 'alter session set use_stored_outlines =
 uw_outlines';

BEGIN
  IF (USER = 'UWCLASS') THEN
    execute immediate sqlstr;
  END IF;
END trace_trig;
/
 
Drop SYSTEM EVENT TRIGGER
Drop Trigger DROP TRIGGER <trigger_name>;
DROP TRIGGER logon_failures;
 
Related Topics
DDL Triggers
Instead Of Trigger
SYS_CONTEXT Function
Table Triggers
 
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