Trigger to Send Seperate Emails per Address on New Subscricption Insert

Question

Hi Everyone,
I am trying to create a trigger that, on insert into and delete from a email_subscription table, will send an email to our MailMan server to subscribe or unsubscribe a member for each email address they have. The problem is I am not sure how to get the information form the other two related tables required to compose the message(s).
The tables are:
Email_Subscription (Member, Email_List)
Email (Member, Email)
EmailList (EmailListID, Email_List)
(where Email_Subscription.Member = Email.Member and Email_Subsciption.Email_List = EmailList.EmailListID)
A Member can have zero or more Email addresses but can only have one Email Subscription per Email List.
So this code:
utl_mail.send(
'[email protected]', --From
EmailList.Email_List || '[email protected]', --To
'', --BCC
'', --CC
'subscribe nodigest address=' || Email.Email, --Subject (subscribe on insert, unsubscribe on delete)
'', --Message
'text/plain; charset=us-ascii', --Email type
3); --Priority
Should be executed for each address the member has when a new email subscription is entered for them or to put it another way, the code should be run for each result of this query:
Select E.email, EL.email_list
From emaillist EL, email E
Where :NEW.member = E.member
And :NEW.email_list = EL.emaillistid
I know how to write a trigger that will insert a record once into another table but cannot work out how to run code for multiple records from related tables.
BTW I am using Oracle XE running on Windows 2003 and Utl_mail is set up and tested.
Any help is much appreciated.

Answer 1

Welcome to OTN.
I'm not sure sending a mail through trigger is at all a good option or not though it sounds rational but would like to share some thoughts.
satyaki>
satyaki>select * from v$version;
BANNER
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod
PL/SQL Release 10.2.0.1.0 - Production
CORE    10.2.0.1.0      Production
TNS for Linux: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production
Elapsed: 00:00:00.08
satyaki>
satyaki>
satyaki>create table email_subq
  2   (  
  3     sr_no       number(5),
  4     s_name      varchar2(40),
  5     s_mail      varchar2(60)
  6   );
Table created.
Elapsed: 00:00:01.02
satyaki>
satyaki>create table send_mail_log
  2    (
  3      recipient_name   varchar2(40),
  4      email_id         varchar2(60)
  5    );
Table created.
Elapsed: 00:00:00.00
satyaki>
satyaki>create or replace trigger subsq_notifier
  2  before insert on email_subq
  3  for each row
  4  begin
  5    insert into send_mail_log values(:new.s_name,:new.s_mail);
  6  end;
  7  /
Trigger created.
Elapsed: 00:00:00.09
satyaki>
satyaki>
satyaki>insert into email_subq values(1,'SATYAKI','[email protected]');
1 row created.
Elapsed: 00:00:00.01
satyaki>
satyaki>select * from email_subq;
     SR_NO S_NAME                                   S_MAIL
         1 SATYAKI                                  [email protected]
Elapsed: 00:00:00.00
satyaki>
satyaki>select * from send_mail_log;
RECIPIENT_NAME                           EMAIL_ID
SATYAKI                                  [email protected]
Elapsed: 00:00:00.00
satyaki>
satyaki>insert into email_subq values('A1','BILLY','[email protected]');
insert into email_subq values('A1','BILLY','[email protected]')
ERROR at line 1:
ORA-01722: invalid number
Elapsed: 00:00:00.01
satyaki>
satyaki>select * from email_subq;
     SR_NO S_NAME                                   S_MAIL
         1 SATYAKI                                  [email protected]
Elapsed: 00:00:00.00
satyaki>
satyaki>select * from send_mail_log;
RECIPIENT_NAME                           EMAIL_ID
SATYAKI                                  [email protected]
Elapsed: 00:00:00.00
satyaki>
satyaki>rollback;
Rollback complete.
Elapsed: 00:00:00.00
satyaki>
satyaki>select * from email_subq;
no rows selected
Elapsed: 00:00:00.00
satyaki>
satyaki>select * from send_mail_log;
no rows selected
Elapsed: 00:00:00.00Now, check the last part. If user somehow rollback it - still your mail will be send to the recipient which might be annoying for the user - i guess. ;)
So, my suggestion would be do not implement this kind of mailing approach through trigger. You can store them in any intermediate table and then after thorough verification you can send the mail using any job or scheduler that available in your version.
Regards.
Satyaki De.