I have two back-end systems (the old one and the new one) that shares an Oracle DB.
In the older system, to save customers data, there are two tables
customers_A
ID NAME ETC
1 PETE ....
customers_B
ID NAME ETC
1 JOSH ...
2 ROSS ...
In the new system I've created a new table called All_Costumer, to join those tables.
This new table contains customer ID's of type A and B respectively.
All_Customers
ID ID_CUSTOMER_A ID_CUSTOMER_B
A19E----D2B0 1 null
A19E----D2B1 null 1
A19E----D2B2 null 2
So, when the new system creates a new customer of type A, data are inserted on customer_A and All_Customers tables, with customer of type B as well.
Currently, the old system is working too, and when a new customer of type A is created, data is inserted only on customer_A table, but I need that data in All_Customers too.
To solve this, I've created a TRIGGER with a MERGE INTO statement inside, to insert a row in All_Customers if doesn't exist on this table (when a new customer of type A are created by the older system)
CREATE OR REPLACE TRIGGER customers_trg
AFTER INSERT
ON customer_A
FOR EACH ROW
DECLARE
variables that doesn't matters
BEGIN
MERGE INTO all_customers
USING (SELECT :new.id id FROM customer_A where id = :new.id) customer
ON (all_customers.id_customer_a = customer.id)
WHEN NOT MATCHED THEN
INSERT (id, id_customer_a)
VALUES (SYS_GUID(), :new.id, null);
COMMIT;
END;
But when I try to create a new customer from the older system, I get this error:
ORA-04091: table **customer_A** is mutating, trigger/function may not see it
Any idea to solve this?
I've tried adding PRAGMA AUTONOMOUS_TRANSACTION; on DECLARE section, but didn't work.
Note: I can't modify the old system
The immediate issue is that you're querying table_a in a trigger against that table; but you don't need to. Your merge query
SELECT :new.id id FROM customer_A where id = :new.id
can simply do
SELECT :new.id id FROM dual
i.e. the clause becomes:
...
USING (SELECT :new.id id FROM dual) customer
ON (all_customers.id_customer_a = customer.id)
...
You also can't commit in a trigger - unless it's autonomous, which this shouldn't be. You said you'd tried that, but it breaks if the insert is rolled back, since the merged row will still exist. So hopefully that commit is just a hang-over from trying and rejecting that approach.
But it works in this db<>fiddle, anyway.
If you weren't adding the GUID you could get the same effect with a view:
create or replace view all_customers (id_customer_a, id_customer_b) as
select id, null from customers_a
union all
select null, id from customers_b;
db<>fiddle
Related
I have two table,and they are connected by one field : B_ID of table A & id of table B.
I want to use sql to insert data to this two table.
how to write the insert sql ?
1,id in table B is auto-increment.
2,in a stupid way,I can insert data to table B first,and then select the id from table B,then add the id to table A as message_id.
You cannot insert data to multiple tables in one SQL statement. Just insert data first to B table and then table A. You could use RETURNING statement to get ID value and get rid of additional select statement between inserts.
See: https://oracle-base.com/articles/misc/dml-returning-into-clause
Have you heard about AFTER INSERT trigger? I think it is what you are looking for.
Something like this might do what you want:
CREATE OR REPLACE TRIGGER TableB_after_insert
AFTER INSERT
ON TableB
FOR EACH ROW
DECLARE
v_id int;
BEGIN
/*
* 1. Select your id from TableB
* 2. Insert data to TableA
*/
END;
/
I'm trying to create a trigger that controls cycles in a self-referencing table.
Unfortunately I've got an error. Could anyone tell me what I'm doing wrong?
CREATE OR REPLACE TRIGGER CHECK_CYCLE
BEFORE INSERT OR UPDATE ON DEPARTMENTS
FOR EACH ROW
BEGIN
IF :NEW.PARENT_ID =
(SELECT ID, PARENT_ID, NAME, LEVEL,
CONNECT_BY_ISLEAF AS ISLEAF,
PRIOR NAME AS PARENT_NAME,
CONNECT_BY_ROOT NAME AS ROOT
FROM DEPARTMENTS
START WITH PARENT_ID IS NULL
CONNECT BY PRIOR ID = PARENT_ID)
THEN
RAISE_APPLICATION_ERROR(20000, 'Sorry.');
END IF;
END;
Error(9,25): PLS-00103: Encountered the symbol "AS" when expecting one of the following:
, from
This seems to be the parser getting confused. If you remove the AS ROOT completely then it reverts to the expected PLS-00405: subquery not allowed in this context error. No idea why it is confused - you can run that query standalone - but since you can't do what you're attempting it's probably not worth worrying about too much.
Your subquery also has three columns and will return multiple rows, so comparing with the current row's scalar PARENT_ID isn't going to work. You could run your subquery separately and select the value you're actually interested in into a local variable, and check against that.
But you have a before-insert trigger and you're querying the table the trigger is against, so you'll get a mutating table exception anyway when you try to insert (or at least, if you try to insert multiple rows at once).
If I understand what you're trying to achieve, you can use an after-insert trigger instead:
create or replace trigger check_cycle
after insert or update on departments
declare
l_hascycle pls_integer;
begin
select max(connect_by_iscycle)
into l_hascycle
from departments
start with parent_id is null
connect by nocycle prior id = parent_id;
if l_hascycle = 1 then
raise_application_error(-20000, 'Sorry.');
end if;
end;
/
This uses the CONNECT_BY_ISCYCLE pseudocolumn, which will be zero for all rows if there is no cycling, and one for any column that cycles. Selecting and checking the max() of that means you'll have a single value of 0 or 1 in the local l_hascycle variable, and you can use that to decide whether to throw an exception.
Inserting a couple of test rows on top of existing non-cycling data such as:
ID PARENT_ID NAME
---------- ---------- ------------
1 Test
2 1 Test
... where the first new row is OK and the second would cause a cycle:
insert into departments (id, parent_id, name) values (3, 2, 'OK');
1 row inserted.
insert into departments (id, parent_id, name) values (2, 3, 'Cycles');
ORA-20000: Sorry.
ORA-06512: at "SCHEMA.CHECK_CYCLE", line 11
ORA-04088: error during execution of trigger 'SCHEMA.CHECK_CYCLE'
The first insert is still in effect (but not yet committed), the second was implicitly rolled back:
select * from departments:
ID PARENT_ID NAME
---------- ---------- ------------
1 Test
2 1 Test
3 2 OK
This won't catch cycles in data that is not connected to an existing tree culminating in a null parent, because of the start with clause; so for exampel with data you could insert 4,5 and 5,4 without raising an exception, as there is no route from either 4 or 5 to a row with a null parent. But that's a different issue and something you might want to test for separately.
It also can't see data from uncommitted changes in other sessions, so it's possible for two sessions to simultaneously insert rows that are valid independently but which still would form a cycle once both are committed.
I think I found the error in your query, it's in this line -
CONNECT_BY_ROOT NAME AS ROOT
which is not built correctly.
Try changing it to something like
CONNECT_BY_ROOT AS ROOT
In PL SQL, I'm writing a stored procedure that uses a DB link:
CREATE OR REPLACE PROCEDURE Order_Migration(us_id IN NUMBER, date_id in DATE)
as
begin
INSERT INTO ORDERS(order_id, company_id)
SELECT ORDER_ID_SEQ.nextval, COMPANY_ID
FROM ORDERS#SOURCE
WHERE USER_ID = us_id AND DUE_DATE = date_ID;
end;
It takes all orders done on a certain day, by a certain user and inserts them in the new database. It calls a sequence to makes sure there are no repeat PKs on the orders, and it works well.
However, I want the same procedure to do a second INSERT into another table that has order_id as a foreign key. So I need to add all the order_id's just created, and the data from SOURCE that matches:
INSERT INTO ORDER_COMPLETION(order_id, completion_dt)
SELECT ????, completion_dt
FROM ORDER_COMPLETION#SOURCE
How can I keep track of which order_id that was just created matches up to the one whose data I need to pull from the source database?
I looked into making a temporary table, but you can't create those in a procedure.
Other info: I'll be calling this procedure from a C# app I'm writing
I'm not sure that I follow the question. If there is an ORDERS table and an ORDER_COMPLETION table in the remote database, wouldn't there be some key on the source system that related those two tables? If that key is the ORDER_ID, why would you want to re-assign that key in your procedure? Wouldn't you want to maintain the ORDER_ID from the source system?
If you do want to re-assign the ORDER_ID locally, I would tend to think that you'd want to do something like
CREATE OR REPLACE PROCEDURE order_migration( p_user_id IN orders.user_id%type,
p_due_date IN orders.due_date%type )
AS
TYPE order_rec IS RECORD( new_order_id NUMBER,
old_order_id NUMBER,
company_id NUMBER,
completion_dt DATE );
TYPE order_arr IS TABLE OF order_rec;
l_orders order_arr;
BEGIN
SELECT order_id_seq.nextval,
o.order_id,
o.company_id,
oc.completion_dt
BULK COLLECT INTO l_orders
FROM orders#source o,
order_completion#source oc
WHERE o.order_id = oc.order_id
AND o.user_id = p_user_id
AND o.due_date = p_due_date;
FORALL i IN l_orders.FIRST .. l_orders.LAST
INSERT INTO orders( order_id, company_id )
VALUES( l_orders(i).new_order_id, l_orders(i).company_id );
FORALL i IN l_orders.FIRST .. l_orders.LAST
INSERT INTO order_completion( order_id, completion_dt )
VALUES( l_orders(i).new_order_id, l_orders(i).completion_dt );
END;
You could also do a single FOR loop with two INSERT statements rather than two FORALL loops. And if you're pulling a lot of data each time, you probably want to pull the data in chunks from the remote system by adding a loop and a LIMIT to the BULK COLLECT
There must be some link between the rows in ORDERS#SOURCE and ORDERS, and between ORDERS#SOURCE and ORDER_COMPLETION#SOURCE, so can you not use a join?
Something like:
INSERT INTO ORDER_COMPLETION(order_id, completion_dt)
SELECT o.order_id, ocs.completion_dt
FROM ORDER_COMPLETION#SOURCE ocs
JOIN ORDERS o ON o.xxx = ocs.xxx
I have an application that uses the Oracle MERGE INTO... DML statement to update table A to correspond with some of the changes in another table B (table A is a summary of selected parts of table B along with some other info). In a typical merge operation, 5-6 rows (out of 10's of thousands) might be inserted in table B and 2-3 rows updated.
It turns out that the application is to be deployed in an environment that has a security policy on the target tables. The MERGE INTO... statement can't be used with these tables (ORA-28132: Merge into syntax does not support security policies)
So we have to change the MERGE INTO... logic to use regular inserts and updates instead. Is this a problem anyone else has run into? Is there a best-practice pattern for converting the WHEN MATCHED/WHEN NOT MATCHED logic in the merge statement into INSERT and UPDATE statements? The merge is within a stored procedure, so it's fine for the solution to use PL/SQL in addition to the DML if that is required.
Another way to do this (other than Merge) would be using two sql statements one for insert and one for update. The "WHEN MATCHED" and "WHEN NOT MATCHED" can be handled using joins or "in" Clause.
If you decide to take the below approach, it is better to run the update first (sine it only runs for the matching records) and then insert the non-Matching records. The Data sets would be the same either way, it just updates less number of records with the order below.
Also, Similar to the Merge, this update statement updates the Name Column even if the names in Source and Target match. If you dont want that, add that condition to the where as well.
create table src_table(
id number primary key,
name varchar2(20) not null
);
create table tgt_table(
id number primary key,
name varchar2(20) not null
);
insert into src_table values (1, 'abc');
insert into src_table values (2, 'def');
insert into src_table values (3, 'ghi');
insert into tgt_table values (1, 'abc');
insert into tgt_table values (2,'xyz');
SQL> select * from Src_Table;
ID NAME
---------- --------------------
1 abc
2 def
3 ghi
SQL> select * from Tgt_Table;
ID NAME
---------- --------------------
2 xyz
1 abc
Update tgt_Table tgt
set Tgt.Name =
(select Src.Name
from Src_Table Src
where Src.id = Tgt.id
);
2 rows updated. --Notice that ID 1 is updated even though value did not change
select * from Tgt_Table;
ID NAME
----- --------------------
2 def
1 abc
insert into tgt_Table
select src.*
from Src_Table src,
tgt_Table tgt
where src.id = tgt.id(+)
and tgt.id is null;
1 row created.
SQL> select * from tgt_Table;
ID NAME
---------- --------------------
2 def
1 abc
3 ghi
commit;
There could be better ways to do this, but this seems simple and SQL-oriented. If the Data set is Large, then a PL/SQL solution won't be as performant.
There are at least two options I can think of aside from digging into the security policy, which I don't know much about.
Process the records to merge row by row. Attempt to do the update, if it fails to update then insert, or vise versa, depending on whether you expect most records to need updating or inserting (ie optimize for the most common case that will reduce the number of SQL statements fired), eg:
begin
for row in (select ... from source_table) loop
update table_to_be_merged
if sql%rowcount = 0 then -- no row matched, so need to insert
insert ...
end if;
end loop;
end;
Another option may be to bulk collect the records you want to merge into an array, and then attempted to bulk insert them, catching all the primary key exceptions (I cannot recall the syntax for this right now, but you can get a bulk insert to place all the rows that fail to insert into another array and then process them).
Logically a merge statement has to check for the presence of each records behind the scenes anyway, and I think it is processed quite similarly to the code I posted above. However, merge will always be more efficient than coding it in PLSQL as it will be only 1 SQL call instead of many.
I have a question regarding a unified insert query against tables with different data
structures (Oracle). Let me elaborate with an example:
tb_customers (
id NUMBER(3), name VARCHAR2(40), archive_id NUMBER(3)
)
tb_suppliers (
id NUMBER(3), name VARCHAR2(40), contact VARCHAR2(40), xxx, xxx,
archive_id NUMBER(3)
)
The only column that is present in all tables is [archive_id]. The plan is to create a new archive of the dataset by copying (duplicating) all records to a different database partition and incrementing the archive_id for those records accordingly. [archive_id] is always part of the primary key.
My problem is with select statements to do the actual duplication of the data. Because the columns are variable, I am struggling to come up with a unified select statement that will copy the data and update the archive_id.
One solution (that works), is to iterate over all the tables in a stored procedure and do a:
CREATE TABLE temp as (SELECT * from ORIGINAL_TABLE);
UPDATE temp SET archive_id=something;
INSERT INTO ORIGINAL_TABLE (select * from temp);
DROP TABLE temp;
I do not like this solution very much as the DDL commands muck up all restore points.
Does anyone else have any solution?
How about creating a global temporary table for each base table?
create global temporary table tb_customers$ as select * from tb_customers;
create global temporary table tb_suppliers$ as select * from tb_suppliers;
You don't need to create and drop these each time, just leave them as-is.
You're archive process is then a single transaction...
insert into tb_customers$ as select * from tb_customers;
update tb_customers$ set archive_id = :v_new_archive_id;
insert into tb_customers select * from tb_customers$;
insert into tb_suppliers$ as select * from tb_suppliers;
update tb_suppliers$ set archive_id = :v_new_archive_id;
insert into tb_suppliers select * from tb_suppliers$;
commit; -- this will clear the global temporary tables
Hope this helps.
I would suggest not having a single sql statement for all tables and just use and insert.
insert into tb_customers_2
select id, name, 'new_archive_id' from tb_customers;
insert into tb_suppliers_2
select id, name, contact, xxx, xxx, 'new_archive_id' from tb_suppliers;
Or if you really need a single sql statement for all of them at least precreate all the temp tables (as temp tables) and leave them in place for next time. Then just use dynamic sql to refer to the temp table.
insert into ORIGINAL_TABLE_TEMP (SELECT * from ORIGINAL_TABLE);
UPDATE ORIGINAL_TABLE_TEMP SET archive_id=something;
INSERT INTO NEW_TABLE (select * from ORIGINAL_TABLE_TEMP);