Imagination To Realization

Transcription

1 Imagination To Realization Trigger Writing for Fun and Profit Presented by: Larry Holder Database Administrator The University of Tennessee at Martin April 4, :30 11:30 am April 2-5 Orlando, Florida

2 Session Rules of Etiquette Please set your cell phone or pager on stun. If you must leave the session early, please do so as discreetly as possible, and don t let the door hit you on the way out. Please avoid side conversation during the session, unless you are discussing what a fantastic job I m doing up here... Thanks a Gigabyte! 2

3 Introduction This session provides an introduction to writing database triggers, along with several real-world examples that can enhance your support of Banner. 3

4 Imagination To Realization What s a Trigger? April 2-5 Orlando, Florida

5 What s a Trigger? We ain t talkin about Roy s noble steed... Used by permission of the Roy Rogers-Dale Evans Museum, Branson, MO. 5

6 Ok, so... what s a trigger? A PL/SQL object, akin to a Procedure. Most often, a cool, calm & calculated reaction to an event, such as insert, update, delete, or even select, on a table. Sometimes, a reaction to a database event, such as a user logging onto the database. 6

7 What can I do with it? Modify a field before it is inserted or updated. Insert, update, or delete data in other tables. Perform additional error-checking, and prevent an unwanted insert, update, or delete from occurring. Notify someone by about an event. 7

8 What schema owns the custom triggers? We chose to let SATURN own our custom triggers associated with SATURN-owned tables; likewise for GENERAL, WTAILOR, etc. Be sure the owner of the trigger is granted rights on any tables it references or modifies that are owned by another schema. 8

9 What naming convention is used? UTM_ST_SARADAP_PRE_IU_ROW A pre-insert / update trigger, at the row level, on the table SARADAP. UTM is our prefix, and ST is standard for Student Trigger. Remember 30-character object name max within Oracle. Add numeric suffix if a tie-breaker is needed (multiple triggers on same table are allowed). 9

10 Special variables :old.spraddr_street_line1 meaningless for INSERT, will yield NULL :new.spraddr_street_line1 10

11 Special variables INSERTING, UPDATING, DELETING Useful if trigger handles more than one mode, such as both INSERT and UPDATE, and your logic needs to know which occurred. IF INSERTING THEN do this; ELSE do that; END IF; 11

12 Special variables USER - the Oracle userid of who is connected For self-service, keep in mind that the userid is likely something like WWW_USER. SYSDATE - the current date and time DATABASE_NAME Useful to differentiate between production and test: IF substr(database_name,1,4) = 'PROD' 12

13 Examples of Before/After & Row/Statement create or replace trigger trigger_name BEFORE INSERT or UPDATE on table_name for each ROW create or replace trigger trigger_name AFTER DELETE on table_name statement level if no "for each row" Firing order: 1. Before Statement (once only) 2. Before Row (once per each affected row) 3. The actual DML statement 4. After Row (once per each affected row) 5. After Statement (once only) 13

14 Example: Modifying fields "before" create or replace trigger utm_st_sarpers_pre_in_up_row BEFORE INSERT or UPDATE on SARPERS for each ROW BEGIN IF :new.sarpers_last_name IS NOT NULL THEN IF :new.sarpers_last_name = UPPER(:new.sarpers_last_name) OR :new.sarpers_last_name = LOWER(:new.sarpers_last_name) THEN :new.sarpers_prefix := INITCAP(:new.sarpers_prefix); :new.sarpers_first_name := INITCAP(:new.sarpers_first_name); :new.sarpers_middle_name1 := INITCAP(:new.sarpers_middle_name1); :new.sarpers_middle_name2 := INITCAP(:new.sarpers_middle_name2); :new.sarpers_last_name := INITCAP(:new.sarpers_last_name); :new.sarpers_suffix := INITCAP(:new.sarpers_suffix); :new.sarpers_nickname := INITCAP(:new.sarpers_nickname); :new.sarpers_combined_name := INITCAP(:new.sarpers_combined_name); END IF; END IF; END; / :new.sarpers_former_name := INITCAP(:new.sarpers_former_name); 14

15 Example: Writing to an additional table create or replace trigger utm_st_sarctrl_post_ins_row AFTER INSERT on SARCTRL for each ROW DECLARE PRAGMA AUTONOMOUS_TRANSACTION; BEGIN insert into saraatt values (:new.sarctrl_pidm, :new.sarctrl_term_code_entry, :new.sarctrl_appl_no_saradap, 'WAPP', sysdate); COMMIT; EXCEPTION WHEN OTHERS THEN NULL; COMMIT; END; / Note the use, in this example, of autonomous transaction, if you wish or need to commit an action independently of the transaction causing the trigger. Otherwise, a trigger cannot include a commit. 15

16 Example: Additional error checking create or replace trigger utm_st_spriden_pre_insert_row BEFORE INSERT on SPRIDEN for each ROW BEGIN IF :new.spriden_change_ind IS NULL THEN IF (SUBSTR(:new.spriden_id,1,3) = '960' OR SUBSTR(:new.spriden_id,1,1) = '-') OR (SUBSTR(:new.spriden_id,1,1) > '9' AND :new.spriden_entity_ind = 'C') OR (LENGTH(:new.spriden_id) <= 7 AND :new.spriden_entity_ind = 'C') THEN NULL; ELSE RAISE_APPLICATION_ERROR (-20501, 'UTM ERROR *** ADDING THIS ID VALUE IS BLOCKED'); END IF; END IF; END; / 16

17 Example: Sending an notification create or replace trigger utm_st_sortest_post_del_row after DELETE on SORTEST for each ROW w_conn w_crlf w_mailhost w_mesg w_from w_to w_test_ w_stu_id w_stu_name UTL_SMTP.connection; varchar2(2) := CHR(13) CHR(10); varchar2(30) := 'your_ _server'; varchar2(4000); varchar2(30) := 'your_from_address'; varchar2(30) := 'your_recipient_address'; varchar2(30) := 'your_reciepient_for_non_production'; varchar2(9); varchar2(100); BEGIN BEGIN IF SUBSTR(DATABASE_NAME,1,4)!= 'PROD' THEN w_to := w_test_ ; END IF; select spriden_id, spriden_first_name ' ' spriden_last_name into w_stu_id, w_stu_name from spriden where spriden_pidm = :old.sortest_pidm and spriden_change_ind is null; continued... 17

18 Example: Sending an ... (continued) w_mesg := 'Date: ' TO_CHAR(SYSDATE,'DD Mon YY HH24:MI:SS') w_crlf 'From: ' w_from w_crlf 'Subject: ' 'Deletion from SORTEST (SOATEST)' w_crlf 'To: ' w_to w_crlf w_crlf user ' deleted an entry for ' w_stu_name ' (' w_stu_id ') of' ': code = ' :old.sortest_tesc_code ', date = ' to_char(:old.sortest_test_date,'mm-dd-yyyy') ', score = ' :old.sortest_test_score w_crlf w_crlf ' ' w_crlf; w_conn := UTL_SMTP.open_connection(w_mailhost, 25); UTL_SMTP.helo(w_conn, w_mailhost); UTL_SMTP.mail(w_conn, w_from); UTL_SMTP.rcpt(w_conn, w_to); UTL_SMTP.data(w_conn, w_mesg); UTL_SMTP.quit(w_conn); EXCEPTION WHEN OTHERS THEN NULL; END; END; / 18

19 Disabling and enabling a trigger alter trigger [owner.]name DISABLE; alter trigger [owner.]name ENABLE; Automatically enabled when initially created. select * from dba_triggers where trigger_name like 'UTM%'; 19

20 Mutating trigger example create or replace trigger utm_junk1 BEFORE insert or update of spbpers_ssn on SPBPERS for each ROW BEGIN w_pidm w_new_ssn := :new.spbpers_pidm; := :new.spbpers_ssn; DECLARE w_pidm spbpers.spbpers_pidm%type; w_new_ssn spbpers.spbpers_ssn%type; w_flag char(1) := NULL; CURSOR check_for_dup IS select distinct 'Y' from spbpers where spbpers_ssn = w_new_ssn and spbpers_pidm!= w_pidm; IF :new.spbpers_ssn IS NOT NULL THEN OPEN check_for_dup; FETCH check_for_dup INTO w_flag; CLOSE check_for_dup; IF w_flag = 'Y' THEN RAISE_APPLICATION_ERROR(-20501, '*** SSN already in use ***'); END IF; END IF; END utm_junk1; / 20

21 Results (mutation)... ORA-04091: table SATURN.SPBPERS is mutating, trigger/function may not see it ORA-06512: at "SATURN.UTM_JUNK1", line xx ORA-06512: at "SATURN.UTM_JUNK1", line xx ORA-04088: error during execution of trigger 'SATURN.UTM_JUNK1' 21

22 Solution, part 1 of 3 (package) create or replace package utm_st_spbpers_pkg as TYPE t_pidms IS TABLE OF spbpers.spbpers_pidm%type INDEX BY BINARY_INTEGER; TYPE t_new_ssns IS TABLE OF spbpers.spbpers_ssn%type INDEX BY BINARY_INTEGER; pidms new_ssns t_pidms; t_new_ssns; num_entries BINARY_INTEGER := 0; END utm_st_spbpers_pkg; / 22

23 Solution, part 2 of 3 (before / row) create or replace trigger utm_st_spbpers_pre_iu_row BEFORE insert or update of spbpers_ssn on SPBPERS for each ROW BEGIN utm_st_spbpers_pkg.num_entries := utm_st_spbpers_pkg.num_entries + 1; utm_st_spbpers_pkg.pidms (utm_st_spbpers_pkg.num_entries) := :new.spbpers_pidm; utm_st_spbpers_pkg.new_ssns (utm_st_spbpers_pkg.num_entries) := :new.spbpers_ssn; END utm_st_spbpers_pre_iu_row; 23

24 Solution, part 3 of 3 (after / statement) create or replace trigger utm_st_spbpers_post_iu_stmt AFTER insert or update of spbpers_ssn on SPBPERS DECLARE w_num_entries w_pidm w_new_ssn w_flag w_error utm_st_spbpers_pkg.num_entries%type; spbpers.spbpers_pidm%type; spbpers.spbpers_ssn%type; char(1) := NULL; char(1) := 'N'; CURSOR check_for_dup IS select distinct 'Y' from spbpers where spbpers_ssn = w_new_ssn and spbpers_pidm!= w_pidm; continued... 24

25 BEGIN w_num_entries := utm_st_spbpers_pkg.num_entries; FOR z_index IN 1..w_num_entries LOOP w_pidm := utm_st_spbpers_pkg.pidms (z_index); w_new_ssn := utm_st_spbpers_pkg.new_ssns (z_index); IF w_new_ssn IS NOT NULL THEN OPEN check_for_dup; FETCH check_for_dup INTO w_flag; CLOSE check_for_dup; IF w_flag = 'Y' THEN w_error := 'Y'; END IF; END IF; END LOOP; continued... 25

26 IF w_error = 'Y' THEN utm_st_spbpers_pkg.num_entries := 0; RAISE_APPLICATION_ERROR(-20501, '*** SSN ALREADY IN USE ***'); END IF; utm_st_spbpers_pkg.num_entries := 0; END utm_st_spbpers_post_iu_stmt; / 26

27 New Results (no mutation)... ORA-20501: *** SSN ALREADY IN USE *** This is the application error that we intentionally raised ORA-06512: at "SATURN.UTM_SPBPERS_POST_IU_STMT", line xx ORA-04088: error during execution of trigger 'SATURN.UTM_SPBPERS_POST_IU_STMT' This is expected 27

28 Summary Triggers are a great way to extend the functionality of Banner without introducing baseline modifications. Rome wasn t built in a day. Start out simply, and add more at your own pace. 28

29 Questions & Answers Ok, it s your turn... 29

30 Thank You! Larry Holder Please complete the online Evaluation Form 30

31 Without limitation, SunGard, the SunGard logo, Banner, Campus Pipeline, Luminis, PowerCAMPUS, Matrix, and Plus are trademarks or registered trademarks of SunGard Data Systems Inc. or its subsidiaries in the U.S. and other countries. Third-party names and marks referenced herein are trademarks or registered trademarks of their respective owners SunGard. All rights reserved 31