I have created forms in which the user can enter data. With collections the information is saved and will be inserted in the corresponding tables after the forms are submitted.
Now one column in the table has remained empty and I am not sure how to solve it in APEX.
Namely, the table has a foreign key to another table.
But the ID of this table is generated only after submitting the forms.
Can I solve it, for example, with a trigger that then enters the foreign key into the table after the forms are submitted?
Would it be an after insert trigger like this:
CREATE OR REPLACE TRIGGER INSERT_FK
AFTER INSERT
ON TBL1
FOR EACH ROW
begin
INSERT INTO TBL2
VALUES (:NEW.STUID);
EXCEPTION
WHEN NO_DATA_FOUND
THEN
DBMS_OUTPUT.put_line (TO_CHAR (SQLERRM (-20299)));
WHEN OTHERS
THEN
DBMS_OUTPUT.put_line (TO_CHAR (SQLERRM (-20298)));
end;
or is there another better solution for this?
I would not use a trigger for that, but handle this in your application.
You can achieve this by using the RETURNING INTO clause. That allows you to reuse the value of an inserted column in the same transaction.If this is in an anonymous pl/sql block in a page process it would be something like this:
DECLARE
l_id table1.id%TYPE;
BEGIN
INSERT INTO table1(val) VALUES ('Europe')
RETURNING id INTO l_id;
INSERT INTO table2(continent_id, val) VALUES (l_id,'Belgium');
END;
/
In an apex form, you have an option to return the primary key into a page item after insert/update so you can use it in other processes if you use the built-in form processing.
This won't work; you'd insert only the :new.stuid column value into TBL2 which "might" succeed (if other columns in tbl2 aren't NOT NULL), but - all other columns will remain empty.
I guess you should prepare all data while you're still in Apex (i.e. fetch primary key for tbl1 and - at the same time - use it as a foreign key value for tbl2). Otherwise, there's no way to populate that information later because there's no other relation between these two tables (if there were, you wouldn't need the foreign key column, would you?).
Related
I created the trigger but it doesn't move data to the other table
It creates the trigger successfully. It also truncates the table but the data is not moved.
CREATE OR REPLACE TRIGGER test_trigger
BEFORE TRUNCATE ON SCHEMA
BEGIN
IF (ora_sysevent='TRUNCATE' and ora_dict_obj_name='testtab') THEN
INSERT INTO testtab2
SELECT name, id FROM testtab;
END IF;
END test_trigger;
From the other references your source table does not have a quoted identifier, so it will be stored in uppercase in the data dictionary etc. Read more in the docs.That means you need the comparison to be uppercase too:
and ora_dict_obj_name='TESTTAB'
Not related, but it is good practice for your insert statement to list the target column names:
INSERT INTO testtab2 (name, id)
SELECT name, id FROM testtab;
I have one table in oracle where data gets inserted from some third party. I want to populate master tables from that table. So, what will be the best way performance wise using collection.
E.g. Suppose, the table into which data will get populated from third party is 'EMP_TMP'.
Now I want to populate 'EMPLOYEE' master table through procedure which will get populated from EMP_TMP Table.
Here again there is one condition like IF SAME EMPID (this is not primary key) EXISTS then we have to UPDATE FULL TABLE which consists of SAME EMPID ELSE we have INSERT NEW RECORD.
[Note: Here EMPID is VARCHAR2 and EMPNO will be primary key where we will use SEQUENCE]
I think here merge will not perform much better performancewise since we cant use collection in MERGE statement.
Well, if performance is your primary consideration, and you don't like MERGE, then how about this (run as script, single transaction):
delete from EMPLOYEE where emp_id IN (
select emp_id from EMP_TMP);
insert into EMPLOYEE
select * from EMP_TMP;
commit;
Obviously not the "safest" approach (and as written assumes exact same table definitions and you have the rollback), but should be fast (you could also mess with IN vs EXISTS etc). And I couldn't quite understand your post if emp_id or emp_no was the common key in these 2 tables, but use whichever makes sense in your situation.
Create a procedure, you need to be using PL/SQL.
Do an update first then test sql%rowcount.
If it is 0, no updates where done and you have to do an insert instead.
I think that this is fairly efficient.
pseudo code
Update table;
if sql%rowcount = 0 then
//get new sequence number
insert into table;
END IF;
COMMIT;
HTH
Harv
I have a trigger that is fire on inserting a new record in table in that i want to insert new record in the same table.
My trigger is :
create or replace trigger inst_table
after insert on test_table referencing new as new old as old
for each row
declare
df_name varchar2(500);
df_desc varchar2(2000);
begin
df_name := :new.name;
df_desc := :new.description;
if inserting then
FOR item IN (SELECT pid FROM tbl2 where pid not in(1))
LOOP
insert into test_table (name,description,pid) values(df_name,df_desc,item.pid);
END LOOP;
end if;
end;
its give a error like
ORA-04091: table TEST_TABLE is mutating, trigger/function may not see it
i think it is preventing me to insert into same table.
so how can i insert this new record in to same table.
Note :- I am using Oracle as database
Mutation happens any time you have a row-level trigger that modifies the table that you're triggering on. The problem, is that Oracle can't know how to behave. You insert a row, the trigger itself inserts a row into the same table, and Oracle gets confused, cause, those inserts into the table due to the trigger, are they subject to the trigger action too?
The solution is a three-step process.
1.) Statement level before trigger that instantiates a package that will keep track of the rows being inserted.
2.) Row-level before or after trigger that saves that row info into the package variables that were instantiated in the previous step.
3.) Statement level after trigger that inserts into the table, all the rows that are saved in the package variable.
An example of this can be found here:
http://asktom.oracle.com/pls/asktom/ASKTOM.download_file?p_file=6551198119097816936
Hope that helps.
I'd say that you should look at any way OTHER than triggers to achieve this. As mentioned in the answer from Mark Bobak, the trigger is inserting a row and then for each row inserted by the trigger, that then needs to call the trigger to insert more rows.
I'd look at either writing a stored procedure to create the insert or just insert via a sub-query rather than by values.
Triggers can be used to solve simple problems but when solving more complicated problems they will just cause headaches.
It would be worth reading through the answers to this duplicate question posted by APC and also these this article from Tom Kyte. BTW, the article is also referenced in the duplicate question but the link is now out of date.
Although after complaining about how bad triggers are, here is another solution.
Maybe you need to look at having two tables. Insert the data into the test_table table as you currently do. But instead of having the trigger insert additional rows into the test_table table, have a detail table with the data. The trigger can then insert all the required rows into the detail table.
You may again encounter the mutating trigger error if you have a delete cascade foreign key relationship between the two tables so it might be best to avoid that.
I have a database with tables that are chained together with foreign keys, and the last one in the chain also has a foreign key to itself. I want to delete them with cascade on, exapt for the last one in the chain. That one should be set null, unless it's parent record has a certain value. I figured i would do that with a trigger: whenever the last table updated, if the foreign key to itself had been set to null, check the field in the parent record, and if it is the value "default", delete the record in the last table.
However, I haven't found any help online indicting that comparing a parent record in another table.
Is this possible?
In general, a row-level trigger on table A cannot query table A. Doing so would generally raise a mutating table exception (ORA-04091). So a trigger is generally not the right solution.
Presumably, you have some sort of API (i.e. a stored procedure) to delete records from the parent table. That API should query this last table before issuing the DELETE against the parent table. It should take care of updating the last table in the chain as well as deleting the data from the parent table.
If you really wanted a trigger-based solution, life would get substantially more complicated. You could work around the mutating table exception by
Creating a package with a collection of primary keys from the parent table
Creating a before statement trigger that initializes this collection
Creating a row-level trigger that populates the collection with the primary keys that were modified by the SQL statement
Creating an after statement trigger that iterates over the collection and issues whatever DML is necessary (unlike row-level triggers, statement-level triggers on table A can query or modify table A).
If you're using 11g, you can simplify this a bit with a compound trigger with before statement, after row, and after statement sections. But you've still got a number of moving pieces to try to coordinate.
AFAIK you won't be able to really delete the record in the last table (mutating table problem), but you could update a status field indicating the record has been logically deleted (untested):
create or replace trigger last_table_trig
before update on last_table
for each row
declare
l_parentField varchar2(100);
begin
if :new.self_ref_fk is null then
select p.parent_field into l_parentField from parent_table p
where p.pk = :new.parent_fk;
if l_parentField = 'default' then
:new.status := 'DELETED';
end if;
end if;
end;
Hi I have a database with loads of columns and I want to insert couple of records for testing, now in order to insert something into that database I'd have to write large query .. is it possible to do something like this
INSERT INTO table (SELECT FROM table WHERE id='5') .. I try to insert the row with ID 5 but I think this will create a problem because it will try to duplicate a record, is it possible to change this ID 5 to let say 1000 then I'd be able to insert data without writing complex query and while doing so avoiding replication of data .. tnx
In PL/SQL you can do something like this:
declare
l_rec table%rowtype;
begin
select * into l_rec from table where id='5';
l_rec.id := 1000;
insert into table values l_rec;
end;
If you have a trigger on the table to handle the primary key from a sequence (:NEW.id = seq_sequence.NEXTVAL) then you should be able to do:
INSERT INTO table
(SELECT columns_needed FROM table WHERE whatever)
This will allow you to add in many rows at one (the number being limited by the WHERE clause). You'll need to select the columns that are required by the table to be not null or not having default values. Beware of any unique constraints as well.
Otherwise you'll be looking at PL/SQL or some other form of script to insert multiple rows.
For each column that has no default value or you want to insert the values other than default, you will need to provide the explicit name and value.
You only can use an implicit list (*) if you want to select all columns and insert them as they are.
Since you are changing the PRIMARY KEY, you need to enumerate.
However, you can create a before update trigger and change the value of the PRIMARY KEY in this trigger.
Note that the trigger cannot reference the table itself, so you will need to provide some other way to get the unique number (like a sequence):
CREATE TRIGGER trg_mytable_bi BEFORE INSERT ON mytable FOR EACH ROW
BEGIN
:NEW.id := s_mytable.nextval;
END;
This way you can use the asterisk but it will always replace the value of the PRIMARY KEY.