I need a query to move a record from one table to another without using multiple statements?
No, you cannot move records in one SQL statement. You have to use an INSERT followed by a DELETE statement. You should wrap these statements into a transaction, to make sure that the copy operation remains atomic.
START TRANSACTION;
INSERT INTO
new_table
SELECT
*
FROM
old_table
WHERE
some_field = 'your_criteria';
DELETE FROM old_table WHERE some_field = 'your_criteria';
COMMIT;
If you really want to do this in a single SQL statement, one way to accomplish this would be to create an "after delete" trigger on the source table that inserts the row into the target table. This way you can move the row from the source table to the target table simply by deleting it from the source table. Of course this will only work if you want to insert into target table for every delete on the source table.
DELIMITER $$
DROP TRIGGER IF EXISTS TR_A_DEL_SOURCE_TABLE $$
CREATE TRIGGER TR_A_DEL_SOURCE_TABLE AFTER DELETE ON SOURCE_TABLE FOR EACH ROW BEGIN
INSERT IGNORE INTO TARGET_TABLE(id,val1,val2) VALUES(old.id,old.va1,old.val2);
END $$
DELIMITER ;
So to move the row with id 42 from source table to target table:
delete from source_table where id = 42;
No - you might be able to do the INSERT in one nested statement, but you still need to remove the record.
There is no way to make it a single query, but if you HAVE to do it in a single query within an application you can create a Stored Procedure to do it for you.
DELIMITER $$
DROP PROCEDURE IF EXISTS `copydelete` $$
CREATE PROCEDURE `copydelete` (id INT)
BEGIN
INSERT INTO New_Table SELECT * from Old_Table WHERE Old_Table.IdField=id;
DELETE FROM Old_Table where IdField=id;
END $$
DELIMITER ;
Then you're new query is just
CALL copydelete(4);
Which will delete WHERE IdField=4;
Please note that the time delay between insert-select and delete can cause you to delete to much.
For a safe route you could use an update field:
update old_table set move_flag=1 where your_criteria
insert into ... select from ... where move_flag = 1
delete from old_table where move_flag=1
Or use a transaction which locks the old_table so no data can be added between insert... select and delete.
Related
I'm trying to set an "after insert" trigger that executes a procedure. The procedure would take all inserted rows in table A, group them by a column and insert the result in a table B. I know about "new" variable but it gets inserted rows one by one. Is it possible to get all of them?
I think I can't use a for each row statement as I need to group rows depending on the "trackCode" variable, shared by different rows in tableA.
CREATE OR REPLACE PROCEDURE Public.my_procedure(**inserted rows in tableA?**)
LANGUAGE 'plpgsql'
AS $$
BEGIN
INSERT INTO Public."tableB" ("TrackCode", "count")
SELECT "TrackCode", count(*) as "count" FROM Public."tableA" --new inserted rows in this table
GROUP BY "vmsint"."TrackCode" ;
COMMIT;
END;
$$;
create trigger Public.my_trigger
after insert ON Public.tableA
execute procedure Public.my_procedure(**inserted rows in tableA?**)
Thank you!
You create a statement lever trigger, but do not attempt to pass parameters. Instead use the clause referencing new table as reference_table_name. In the trigger function you use the reference_table_name in place of the actual table name. Something like: (see demo)
create or replace function group_a_ais()
returns trigger
language 'plpgsql'
as $$
begin
insert into table_b(track_code, items)
select track_code, count(*)
from rows_inserted_to_a
group by track_code ;
return null;
end;
$$;
create trigger table_a_ais
after insert on table_a
referencing new table as rows_inserted_to_a
for each statement
execute function group_a_ais();
Do not attempt to commit in a trigger, it is a very bad id even if allowed. Suppose the insert to the main table is part of a larger transaction, which fails later in its process.
Be sure to refer to links provided by Adrian.
I want a trigger that updates the value of a column, but I just want to update a small set of rows that depends of the values of the inserted row.
My trigger is:
CREATE OR REPLACE TRIGGER example
AFTER INSERT ON table1
FOR EACH ROW
BEGIN
UPDATE table1 t
SET column2 = 3
WHERE t.column1 = :new.column1;
END;
/
But as I using FOR EACH ROW I have a problem when I try it, I get the mutating table runtime error.
Other option is not to set the FOR EACH ROW, but if I do this, I dont know the inserted "column1" for comparing (or I dont know how to known it).
What can I do for UPDATING a set of rows that depends of the last inserted row?
I am using Oracle 9.
You should avoid the DML statements on the same table as defined in a trigger. Use before DML to change values of the current table.
create or replace trigger example
before insert on table1
for each row
begin
:new.column2 := 3;
end;
/
You can modify the same table with pragma autonomous_transaction:
create or replace trigger example
after insert on table1 for each row
declare
procedure setValues(key number) is
pragma autonomous_transaction;
begin
update table1 t
set column2 = 3
where t.column1 = key
;
end setValues;
begin
setValues(:new.column1);
end;
/
But I suggest you follow #GordonLinoff answere to your question - it's a bad idea to modify the same table in the trigger body.
See also here
If you need to update multiple rows in table1 when you are updating one row, then you would seem to have a problem with the data model.
This need suggests that you need a separate table with one row per column1. You can then fetch the value in that table using join. The trigger will then be updating another table, so there will be no mutation problem.
`create table A
(
a INTEGER,
b CHAR(10)
);
create table B
(
b CHAR (10),
d INTEGER
);
create trigger trig1
AFTER INSERT ON A
REFERENCING NEW AS newROW
FOR EACH ROW
when(newROW.a<=10)
BEGIN
INSERT into B values(:newROW.b,:newROW.a);
END trig1;
insert into A values(11,'Gananjay');
insert into A values(5,'Hritik');
select * from A;
select * from B;`
I've created a trigger as follows:
create or replace trigger "PASSENGERS_BACKUP_T1"
after
insert or update or delete on "PASSENGERS"
for each row
begin
if :NEW."P_ID" is NOT null then
INSERT INTO PASSENGERS_BACKUP(
PB_ID,
PB_FIRST_NAME,
PB_LAST_NAME,
PB_STREET_ADDRESS1,
PB_STREET_ADDRESS2,
PB_CITY,
PB_STATE,
PB_POSTAL_CODE,
PB_EMAIL,
PB_PHONE_NUMBER1,
PB_PHONE_NUMBER2,
PB_URL,
PB_CREDIT_LIMIT,
PB_TAGS)
VALUES (
:new.P_ID,
:new.P_FIRST_NAME,
:new.P_LAST_NAME,
:new.P_STREET_ADDRESS1,
:new.P_STREET_ADDRESS2,
:new.P_CITY,
:new.P_STATE,
:new.P_POSTAL_CODE,
:new.P_EMAIL,
:new.PHONE_NUMBER1,
:new.PHONE_NUMBER1,
:new.URL,
:new.CREDIT_LIMIT,
:new.TAGS);
end if;
end;
now, when I update​ an existing row in "passengers" table as per the above trigger another new row is getting added in "passengers_backup" table instead I would like to update the existing row whenever an update is done in "passengers" table rows. As, well If I delete a row in "Passengers" table, if that row exists in 'Passengers_backup' table it should also get deleted. How can I acheive this?
Thanks in advance.
For solving your problem you need to use trigger with corresponding SQL statement for each action: insert, update, delete. As variant you can use something like this (Note, I left only two columns from your example for readability, so modify your trigger as you need):
create or replace trigger "PASSENGERS_BACKUP_TIUD"
after insert or update or delete on "PASSENGER"
for each row
begin
if inserting then
insert into "PASSENGER_BACKUP" (pb_id, pb_first_name)
values (:NEW.pb_id, :NEW.pb_first_name);
elsif updating then
update "PASSENGER_BACKUP"
set pb_id=:NEW.pb_id, pb_first_name=:NEW.pb_first_name
where pb_id=:NEW.pb_id;
elsif deleting then
delete from "PASSENGER_BACKUP"
where pb_id=:OLD.pb_id;
end if;
end;
Also you can see work of this trigger in action on SQL Fiddle.
How do I write an Oracle trigger, than when a user deletes a certain record, the delete doesnt actually happen, but instead performs an update on those rows and sets the status of the record to 'D'?
I tried:
create or replace
trigger DELFOUR.T4M_ITEM_ONDELETE
before delete on M_ITEM_H
FOR EACH ROW
BEGIN
UPDATE
M_ITEM_H
SET
ITEM_STAT = 'D'
WHERE
CUST_CODE = 'TEST'
AND ITEM_CODE = 'GDAY'
;
raise_application_error(-20000,'Cannot delete item');
END;
But I am getting mutating table errors. Is this possible?
If you really need a trigger, the more logical approach would be to create a view, create an INSEAD OF DELETE trigger on the view, and to force the applications to issue their deletes against the view rather than against the base table.
CREATE VIEW vw_m_item_h
AS
SELECT *
FROM m_item_h;
CREATE OR REPLACE TRIGGER t4m_item_ondelete
INSTEAD OF DELETE ON vw_m_item_h
FOR EACH ROW
AS
BEGIN
UPDATE m_item_h
SET item_stat = 'D'
WHERE <<primary key>> = :old.<<primary key>>;
END;
Better yet, you would dispense with the trigger, create a delete_item procedure that your application would call rather than issuing a DELETE and that procedure would simply update the row to set the item_stat column rather than deleting the row.
If you really, really, really want a solution that involves a trigger on the table itself, you could
Create a package with a member that is a collection of records that map to the data in the m_item_h table
Create a before delete statement-level trigger that empties this collection
Create a before delete row-level trigger that inserts the :old.<<primary key>> and all the other :old values into the collection
Create an after delete statement-level trigger that iterates through the collection, re-inserts the rows into the table, and sets the item_stat column.
This would involve more work than an instead of trigger since you'd have to delete and then re-insert the row and it would involve way more moving pieces so it would be much less elegant. But it would work.
First of all the trigger you wrote would throw a mutating table error. Technically what you are asking is not possible i.e. delete wouldn't delete but rather update, unless you raise an exception in the middle which could be an ugly way of doing it. I would think users using some sort of application front end which lets them delete data using a delete button, so you may use an update statement there instead of a delete statement.
Another option would be to create a log table, where you could insert the record before deleting it from the actual table and then join the log table with the actual table to retrieve deleted records. Something like-
CRETAE TABLE M_ITEM_H_DEL_LOG as SELECT * FROM M_ITEM_H WHERE 1=2;
And then
create or replace
trigger DELFOUR.T4M_ITEM_ONDELETE
before delete on M_ITEM_H
FOR EACH ROW
BEGIN
INSERT INTO
M_ITEM_H_DEL_LOG
VALUES (:old.col1, :old.col2,.....) --col1, col2...are columns in M_ITEM_H
;
END;
I want to run a trigger when I update a certain field on the database, so it updates another field (basically we have 2 different unique IDs for each record, so when one is changed, we need to update the other too - yay!)
CREATE OR REPLACE TRIGGER trigger_name ON table AFTER
UPDATE AS
UPDATE table A
SET unique_to_update = NVL(
(SELECT b.unique_to_update_from
FROM table b
WHERE B.other_unique_id = A.unique_id_to_match
), 0);
I have no idea if this works (scared to test it, quite frankly, since I'm certain it'll break things) and even if it did, it'd run on every single update of that table - not just the one field that I wanted.
Any help would be much appreciated, thank you!
Test anything before putting it in production.
Something like this shoud be your trigger:
CREATE OR REPLACE TRIGGER trigger_name
BEFORE UPDATE of unique_id_to_match
ON table
FOR EACH ROW
AS
BEGIN
select
NVL(
(SELECT b.unique_to_update_from
FROM table b
WHERE B.other_unique_id = :new.unique_id_to_match
), 0)
into :new.unique_to_update
FROM dual;
END;
5000 rows x 900 columns is not so big :)
I was afraid it has 10M of rows :)
OK start
create temporary table tmp_my_important_columns on commit delete rows
as
select unique_id_to_match, unique_to_update_from,
other_unique_id , unique_to_update
from table where rownum < 1;
second
CREATE OR REPLACE TRIGGER trigger_before_upd_stmt
BEFORE UPDATE
ON table
AS
BEGIN
insert into
tmp_my_important_columns
select unique_id_to_match, unique_to_update_from,
other_unique_id , unique_to_update
from table;
END;
third,
CREATE OR REPLACE TRIGGER trigger_name
BEFORE UPDATE of unique_id_to_match
ON table
FOR EACH ROW
AS
BEGIN
select
NVL(
(SELECT b.unique_to_update_from
FROM tmp_my_important_columns b
WHERE B.other_unique_id = :new.unique_id_to_match
), 0)
into :new.unique_to_update
FROM dual;
END;
Comments:
After an update, if you update the same rows again, without commit
(which deletes the tmp table), you'll get problems. So, or you commit
after update, or you can add an after update trigger(without for each row) that deletes all, from tmp table, but this is somehow ugly.
You can add indexes on the temporary table.