Want to modify existing trigger

Question

I  have tried  to find  logon/logoff  details using  trigger program.
1)  trigger_logon  for  login time/date with user ans host information.
2)  trigger_logoff  for  login time.
SQL> create or replace trigger tri_audit
  2  AFTER LOGON ON DATABASE
  3  declare
  4  user varchar2(30);
  5  sess_id number;
  6  logdate date;
  7  login_time VARCHAR2(15);
  8  EXTERNAL_NAME VARCHAR2(15);
  9  AUTHENTICATION_TYPE VARCHAR2(15);
10  HOST varchar2(10);
11  begin
12  select sys_context('USERENV','SESSION_USER') into user from dual;
13  select sys_context('USERENV','SESSIONID') into sess_id from dual;
14  select sys_context('USERENV','EXTERNAL_NAME') into EXTERNAL_NAME from dual;
15  select sys_context('USERENV','AUTHENTICATION_TYPE') into AUTHENTICATION_TYPE  from dual;
16  select sys_context('USERENV','host') into host from dual;
17  select (sysdate) into LOGDATE from dual;
18  select to_char(SYSDATE,'HH24:MM:SS') into LOGIN_TIME from dual;
19  insert into user_login values (user,sess_id,EXTERNAL_NAME,AUTHENTICATION_TYPE,host,
20  logdate,login_time);
21  end;
22  /
Warning: Trigger created with compilation errors.
SQL> show errors;
Errors for TRIGGER TRI_AUDIT:
LINE/COL ERROR
17/1     PL/SQL: SQL Statement ignored
17/13    PL/SQL: ORA-00947: not enough values
Please help me  to solve my problem.
table details
SQL> desc user_login
Name                                      Null?    Type
USERNAME                                      VARCHAR2(15)
ISDBA                                               VARCHAR2(15)
LOGDATE                                         DATE
LOGIN_TIME                                     VARCHAR2(15)
LOGOUT_TIME                                VARCHAR2(15)
EXTERNAL_NAME                          VARCHAR2(15)
AUTHENTICATION                           VARCHAR2(15)
HOST                                               VARCHAR2(10)
SESSION_ID                                    NUMBER

Answer 1

count the number of columns in your table. there are 9.
now count the number of values you are trying to insert in your statement
insert into user_login values (user,sess_id,EXTERNAL_NAME,AUTHENTICATION_TYPE,host,sysdate ,login_time);
there are only 7.
9 <> 7
you must have the same number of values to insert as the number of columns.
one way to ensure this is to always use a column list like this
insert into user_login (username,session_id,external_name, authentication, host, logdate, login_time)
values (user,sess_id,EXTERNAL_NAME,AUTHENTICATION_TYPE,host,sysdate ,login_time);
rather than what you're doing. Anyway, it is just good practice to always include the column list because if the underlying table structure changes, it will not fail.