How to audit the table when updated. The table has 100 Columns.

Question

Hi,
I have a requirement to keep the log information of a table whenever there is an update happening on any of the columns available in a table, which has roughly 100 columns. I know we can use :NEW and :OLD specifier using trigger, but the no of columns are 100 + , here shall we fulfill the requirement. Kindly suggest if you have any better way to handle it.
Regards
Suresh

Answer 1

You can use XMLTYPE for this. See an example below:
First creating some test data:
SQL> create table test_06302011
  2  (
  3    a1 number(10)
  4  , a2 number(10)
  5  , a3 number(10)
  6  , a4 number(10)
  7  , a5 number(10)
  8  , a6 number(10)
  9  )
10  /
Table created.
SQL> insert into test_06302011
  2  values(1,1,1,1,1,1)
  3  /
1 row created.
SQL> insert into test_06302011
  2  values(2,2,2,2,2,2)
  3  /
1 row created.
SQL> insert into test_06302011
  2  values(3,3,3,3,3,3)
  3  /
1 row created.
SQL> insert into test_06302011
  2  values(4,4,4,4,4,4)
  3  /
1 row created.
SQL> insert into test_06302011
  2  values(5,5,5,5,5,5)
  3  /
1 row created.
SQL> insert into test_06302011
  2  values(6,6,6,6,6,6)
  3  /
1 row created.
SQL> commit
  2  /
Commit complete.
SQL> create table log_06302011
  2  (
  3    log_id     number(10) primary key
  4  , log_date   date
  5  , log_action varchar2(1)
  6  , log_old    xmltype
  7  , log_new    xmltype
  8  )
  9  /
Table created.Then creating the logging trigger:
SQL> CREATE OR REPLACE TRIGGER trigger_log_06302011
  2     AFTER UPDATE OR INSERT OR DELETE ON test_06302011
  3     FOR EACH ROW
  4  DECLARE
  5      vlog_event VARCHAR2(1);
  6      v_log_new  XMLTYPE;
  7      v_log_old  XMLTYPE;
  8  BEGIN
  9
10    IF INSERTING THEN
11        vlog_event := 'I';
12        select XMLELEMENT("test_06302011",
13                        XMLFOREST(
14                            :new.a1 as "a1"
15                          , :new.a2 as "a2"
16                          , :new.a3 as "a3"
17                          , :new.a4 as "a4"
18                          , :new.a5 as "a5"
19                          , :new.a6 as "a6")
20                   )
21           into v_log_new
22           from dual;
23
24         v_log_old := NULL;
25
26    END IF;
27
28    IF UPDATING THEN
29        vlog_event := 'U';
30        select XMLELEMENT("test_06302011",
31                        XMLFOREST(
32                            :new.a1 as "a1"
33                          , :new.a2 as "a2"
34                          , :new.a3 as "a3"
35                          , :new.a4 as "a4"
36                          , :new.a5 as "a5"
37                          , :new.a6 as "a6")
38                   )
39           into v_log_new
40           from dual;
41
42         select XMLELEMENT("test_06302011",
43                        XMLFOREST(
44                                                           :old.a1 as "a1"
45                                                         , :old.a2 as "a2"
46                                                         , :old.a3 as "a3"
47                                                         , :old.a4 as "a4"
48                                                         , :old.a5 as "a5"
49                                                         , :old.a6 as "a6")
50                   )
51          into v_log_old
52          from dual;
53
54    END IF;
55
56    IF DELETING THEN
57        vlog_event := 'D';
58        v_log_new := NULL;
59
60         select XMLELEMENT("test_06302011",
61                        XMLFOREST(
62                                                           :old.a1 as "a1"
63                                                         , :old.a2 as "a2"
64                                                         , :old.a3 as "a3"
65                                                         , :old.a4 as "a4"
66                                                         , :old.a5 as "a5"
67                                                         , :old.a6 as "a6")
68                   )
69          into v_log_old
70          from dual;
71
72    END IF;
73
74     INSERT INTO log_06302011 (log_id, log_date, log_action, log_old, log_new
75     VALUES ((SELECT NVL(MAX(log_06302011.log_id), 0) + 1 FROM log_06302011)
76          , SYSDATE
77          , vlog_event
78          , v_log_old
79          , v_log_new
80           );
81
82  END trigger_log_06302011;
83  /
Trigger created.Now test:
SQL> update test_06302011
  2     set a2 = 99
  3   where a1 = 1
  4  /
1 row updated.
SQL> commit
  2  /
Commit complete.
SQL> column log_old format a30
SQL> column log_new format a30
SQL> set linesize 300
SQL> select log_old, log_new from log_06302011;
LOG_OLD                        LOG_NEW
<test_06302011><a1>1</a1><a2>1 <test_06302011><a1>1</a1><a2>9
</a2><a3>1</a3><a4>1</a4><a5>1 9</a2><a3>1</a3><a4>1</a4><a5>
</a5><a6>1</a6></tes           1</a5><a6>1</a6></te
SQL>