I want to create a trigger that after insert on another table it truncates another and after that inserts the data from the first table into the truncated one. I have managed the insert part but i don't know how to incorporate the truncate command into the same trigger.
CREATE OR REPLACE TRIGGER TEST_TRIGGER AFTER INSERT ON TEST
FOR EACH ROW
BEGIN
INSERT INTO TEST2
(col1, col2, col3)
VALUES
(:NEW.col1, :NEW.col2, :NEW.col3);
END;
Below is the snipped using which you can achieve your goal
create table table1 (id int, age number,name varchar2(100));
create table table2 (id int, age number,name varchar2(100));
create or replace trigger sandeeptest after insert on table1 for each row
declare
PRAGMA AUTONOMOUS_TRANSACTION;
begin
execute immediate 'truncate table table2';
insert into table2(id,age,name) values (:new.id,:new.age,:new.name);
commit;
end;
insert into table1 (id,age,name) values (1,21,'A');
commit; -- after commit data is persisted in both the tables
insert into table1 (id,age,name) values (2,21,'B');
rollback;-- even after rollback data is presisted in table2 because we created an autonomous trigger
select * from table1;
select * from table2;
you can create procedure on target schema which you want to truncate table on it.
the proc like this:
CREATE OR REPLACE procedure target_schema.pr_truncate_table(p_table_name varchar2) is
begin
execute immediate 'truncate table ' || p_table_name;
end;
/
then you can use it on trigger.
Surely using transactional statement inside trigger is not a good idea. But i guess you are in some practical and more significant use of it.
If you use DELETE inside trigger instead of TRUNCATE, will have
slow performance in case of large table
Most important, you will have to COMMIT which is again not allowed unless you use PRAGMA AUTONOMOUS_TRANSACTION
If you create two procedure , one to INSERT and another to TRUNCATE,will have:
since procedure is having commit(implicit or external), trigger needs to be defined PRAGMA AUTONOMOUS_TRANSACTION (which is again needed)
BUT think more than twice before making it autonomous. It is double sided sword which may hurt your business logic in case of rollback because you can not rollback DDL statement.
I would suggest to use dbms_job and submit procedure to it.
CREATE OR REPLACE TRIGGER TEST_TRIGGER AFTER INSERT ON TEST
FOR EACH ROW
BEGIN
DELETE FROM TEST2 WHERE true ;
INSERT INTO TEST2
(col1, col2, col3)
VALUES
(:NEW.col1, :NEW.col2, :NEW.col3);
END;
Related
The question I am going to ask is already there. But I don't have answer for this.
Please refer the below link.
ORACLE TRIGGER INSERT INTO ... (SELECT * ...)
I have around 600 columns in a table. After each insert in this table I need to insert the new row in another backup table.
Please tell how to use "INSERT INTO TABLE_NAME2 SELECT * FROM TABLE_NAME1" query in trigger.
Note: Without specifying columns in insert or select clause
Structure of both table is same. Specifying all the column name in trigger is difficult and also if new columns added, we need to add in trigger as well.
SQL> CREATE or REPLACE TRIGGER emp_after_insert AFTER INSERT ON emp
FOR EACH ROW
DECLARE
BEGIN
insert into emp_backup values (:new.empid, :new.fname, :new.lname);
DBMS_OUTPUT.PUT_LINE('Record successfully inserted into emp_backup table');
END;
reference:
http://www.tech-recipes.com/rx/19839/oracle-using-the-after-insert-and-after-update-triggers/
You should use COMPOUND TRIGGER. This trigger should look like this:
CREATE OR REPLACE TRIGGER t_copy_table1
FOR INSERT ON table1
COMPOUND TRIGGER
v_id number;
BEFORE EACH ROW IS
BEGIN
v_id := :new.id;
END BEFORE EACH ROW;
AFTER STATEMENT IS
BEGIN
insert into table2 select * from table1 where id=v_id;
END AFTER STATEMENT;
END t_copy_table1;
I created a database in MySQL with ~10 tables, each starting with the column
SN INT NOT NULL AUTO_INCREMENT
SN doesn't mean anything, just the primary to differentiate between possibly repeating/similar names/titles, etc
I'm moving it to Oracle now, and found this post here on stackoverflow to make the trigger to auto increment the SN field. Basically,
CREATE SEQUENCE user_seq;
CREATE OR REPLACE TRIGGER user_inc
BEFORE INSERT ON users
FOR EACH ROW
BEGIN
SELECT user_seq.NEXTVAL
INTO :new.SN
FROM dual;
END;
/
Now, how can I rewrite that trigger once to apply to all the other tables? Because otherwise I have to rewrite it for many tables, just changing the trigger name and sequence name... I was picturing something like:
BEFORE INSERT ON users OR other_table OR another_one
I also found this post here, but the one answer there isn't helpful because I think it's reasonable for many tables to have the same SN field, or I'm misunderstanding the point.
Also, not Oracle 12c so no identity columns
Thanks in advance
I was going to just comment on the first post I mentioned but I can't comment without more reputation points :/
Creating a trigger referencing many tables in Oracle is not possible,
What you can do is to generate the triggers with a PL/SQL statement.
Below is an example on how could you achieve this
drop table tab_a;
drop table tab_b;
drop table tab_c;
drop sequence seq_tab_a_id;
drop sequence seq_tab_b_id;
drop sequence seq_tab_c_id;
--create test tables
create table tab_a (SN number, otherfield varchar2(30), date_field date);
create table tab_b (SN number, otherfield varchar2(30), date_field date);
create table tab_c (SN number, otherfield varchar2(30), date_field date);
-- this pl/sql block creates the sequences and the triggers
declare
my_seq_create_stmt varchar2(2000);
my_trigger_create_stmt varchar2(2000);
begin
for i in (select table_name
from user_tables
-- remember to change this where condition to filter
-- the tables that are relevant for you
where table_name in ('TAB_A', 'TAB_B', 'TAB_C') )loop <<TableLoop>>
my_seq_create_stmt := 'CREATE SEQUENCE '||'SEQ_'||i.table_name||'_ID '
||CHR(13)||' START WITH 1 INCREMENT BY 1 NOCYCLE ';
execute immediate my_seq_create_stmt;
my_trigger_create_stmt := 'CREATE OR REPLACE TRIGGER '||'TRG_'||i.Table_name||'_ID_BI '||' BEFORE INSERT ON '||i.table_name||' FOR EACH ROW '
||CHR(13)||'BEGIN '
||CHR(13)||' SELECT '||'SEQ_'||i.table_name||'_ID'||'.NEXTVAL '
||CHR(13)||' INTO :new.SN '
||CHR(13)||' FROM dual; '
||CHR(13)||'END; ';
execute immediate my_trigger_create_stmt;
end loop TableLoop;
end;
/
-- test the triggers and the sequences
insert into tab_a (otherfield, date_field) values ('test 1',sysdate);
insert into tab_a (otherfield, date_field) values ('test 2',sysdate);
commit;
Select * from tab_a;
I am performing an archival process on a huge database and it involves deleting the production active table and renaming another table to be the new production table. When dropping the production active table, the triggers also get deleted. So I am just taking a backup of the triggers defined on my table using
select * from all_triggers where table_name=mytablename;
My question is, can I directly copy these triggers in to the all_triggers table after I rename my other table to be the new production active table? Will the triggers still work?
Same question for defining indexes and constraints too.
Copying the triggers from one table to another can be done by copying DDL, and not updating all_triggers table. This can be done by using DBMS_METADATA.
The closest practical example I found here: Copy Triggers when you Copy a Table
The following script can be amended as per your need:
declare
p_src_tbl varchar2(30):= 'PERSONS'; --your table name
p_trg_tbl varchar2(30):= 'PSN2'; --your trigger name
l_ddl varchar2(32000);
begin
execute immediate 'create table '||p_trg_tbl||' as select * from '||p_src_tbl||' where 1=2';
for trg in (select trigger_name from user_triggers where table_name = p_src_tbl) loop
l_ddl:= cast(replace(replace(dbms_metadata.get_ddl( 'TRIGGER', trg.trigger_name),p_src_tbl,p_trg_tbl),trg.trigger_name,substr(p_trg_tbl||trg.trigger_name, 1, 30)) as varchar2);
execute immediate substr(l_ddl, 1, instr(l_ddl,'ALTER TRIGGER')-1);
end loop;
end;
/
No, you cannot directly manipulate data dictionary tables. You can't insert data directly into all_triggers (the same goes for any data dictionary table). I guess you probably could given enough hacking. It just wouldn't work and would render your database unsupported.
The correct way to go is to script out your triggers and reapply them later. If you want to do this programmatically, you can use the dbms_metadata package. If you want to get the DDL for each of the triggers on a table, you can do something like
select dbms_metadata.get_ddl( 'TRIGGER', t.trigger_name, t.owner )
from all_triggers t
where table_owner = <<owner of table>>
and table_name = <<name of table>>
To replicate your scenario i have prepared below snippet. Let me know if this helps.
--Simple example to copy Trigger from one table to another
CREATE TABLE EMP_V1 AS
SELECT * FROM EMP;
--Creating Trigger on Old Table for Example purpose
CREATE OR REPLACE TRIGGER EMP_OLD_TRIGGER
AFTER INSERT OR UPDATE ON EMP FOR EACH ROW
DECLARE
LV_ERR_CODE_OUT NUMBER;
LV_ERR_MSG_OUT VARCHAR2(2000);
BEGIN
dbms_output.put_line('Your code for data Manipulations');
--Like Insert update or DELETE activities
END;
-- To replace this trigger for emp_v2 table
set serveroutput on;
DECLARE
lv_var LONG;
BEGIN
FOR i IN (
SELECT OWNER,TRIGGER_NAME,DBMS_METADATA.GET_DDL('TRIGGER','EMP_OLD_TRIGGER') ddl_script FROM all_triggers
WHERE OWNER = 'AVROY') LOOP
NULL;
lv_var:=REPLACE(i.ddl_script,'ON EMP FOR EACH ROW','ON EMP_V1 FOR EACH ROW');
dbms_output.put_line(substr(lv_var,1,INSTR(lv_var,'ALTER TRIGGER',1)-1));
EXECUTE IMMEDIATE 'DROP TRIGGER '||I.TRIGGER_NAME;
EXECUTE IMMEDIATE lv_var;
END LOOP;
END;
--Check if DDL manipulation has been done for not
SELECT OWNER,TRIGGER_NAME,DBMS_METADATA.GET_DDL('TRIGGER','EMP_OLD_TRIGGER') ddl_script FROM all_triggers
WHERE OWNER = 'AVROY';
---------------------------------OUTPUT----------------------------------------
"
CREATE OR REPLACE TRIGGER "AVROY"."EMP_OLD_TRIGGER"
AFTER INSERT OR UPDATE ON EMP_V1 FOR EACH ROW
DECLARE
LV_ERR_CODE_OUT NUMBER;
LV_ERR_MSG_OUT VARCHAR2(2000);
BEGIN
dbms_output.put_line('Your code for data Manipulations');
--Like Insert update or DELETE activities
END;
"
-----------------------------OUTPUT----------------------------------------------
I'm wondering if I will miss any data if I replace a trigger while my oracle database is in use. I created a toy example and it seems like I won't, but one of my coworkers claims otherwise.
create table test_trigger (id number);
create table test_trigger_h (id number);
create sequence test_trigger_seq;
--/
create or replace trigger test_trigger_t after insert on test_trigger for each row
begin
insert into test_trigger_h (id) values (:new.id);
end;
/
--/
begin
for i in 1..100000 loop
insert into test_trigger (id) values (test_trigger_seq.nextval);
end loop;
end;
/
--/
begin
for i in 1..10000 loop
execute immediate 'create or replace trigger test_trigger_t after insert on test_trigger for each row begin insert into test_trigger_h (id) values (:new.id); end;';
end loop;
end;
/
ran the two loops at the same time
select count(1) from test_trigger;
COUNT(1)
100000
select count(1) from test_trigger_h;
COUNT(1)
100000
create or replace is locking the table. So all the inserts will wait until it completes. Don't worry about missed inserts.
I think you might be going about testing this in the wrong way. Your insert statements won't take any time at all and so the replacement of the trigger can fit in through the gaps between inserts. As least this is what I infer due to the below.
If you change your test to ensure you have a long running SQL statement, e.g.
create table test_trigger (id number);
create table test_trigger_h (id number);
create sequence test_trigger_seq;
create or replace trigger test_trigger_t
after insert on test_trigger for each row
begin
insert into test_trigger_h (id) values (:new.id);
end;
/
insert into test_trigger
select level
from dual
connect by level <= 1000000;
If you then try to replace the trigger in a separate session it will not occur until after the insert has completed.
Unfortunately, I can't find anything in the documentation to back me up; this is just behavior that I'm aware of.
Following URL answers that trigger can be modified while application is running. its will a "library cache" lock and NOT a "data" lock. Oracle handles it internally without you worrying abt it.
Check out question raised by Ben- Can a trigger be locked; how would one determine that it is?
-- Run this from session 2:
select * from v$access where object = upper('test_trigger_t');
I want to create a Statement level Trigger which means I want to insert only one record into table EMP_AUDIT when 1 or more rows are inserted into table EMP. For example: if I have 10 records inserted into EMP, then only 1 record should be inserted into EMP_AUDIT table.
There are no constraints on columns. (i.e. can be NULL)
I tried to use the following trigger but it gives me the Error(2,2): PL/SQL: SQL Statement ignored
Error(2,14): PL/SQL: ORA-00947: not enough values
CREATE OR REPLACE
TRIGGER TRIG_EMP AFTER INSERT ON EMP
BEGIN
INSERT INTO EMP_AUDIT
VALUES (TRANID,EMPNUM,SYSDATE);
END;
CREATE TABLE EMP
(TRANID NUMBER,
EMPNUM VARCHAR2(100),
EMPLOC VARCHAR2(100));
CREATE TABLE EMP_AUDIT
(EVENTID NUMBER,
EMPNUM VARCHAR2(100),
ENTRDATE DATE);
The statement-level trigger (which you have) cannot see the data that was inserted. After all, if there were 10 rows inserted, what values should the columns be for your audit table?
You need a row-level trigger for this to work, e.g.:
CREATE OR REPLACE
TRIGGER TRIG_EMP
AFTER INSERT ON EMP
FOR EACH ROW
BEGIN
INSERT INTO EMP_AUDIT
VALUES (:NEW.TRANID,:NEW.EMPNUM,:NEW.SYSDATE);
END;
Use this piece of code:
CREATE OR REPLACE TRIGGER
TRIG_EMP
AFTER INSERT ON EMP
FOR EACH ROW
BEGIN
INSERT INTO EMP_AUDIT
VALUES (:NEW.TRANID,:NEW.EMPNUM,:NEW.SYSDATE);
END;