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.
Related
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?).
I have created a trigger and was expecting a mutating table error in below case but didn't get one through normal insert but getting an error while inserting using a query. I am not sure which concept I am missing here.
drop table temp;
create table temp (id number,name varchar2(500),is_active number);
create or replace trigger temp_trg before insert on temp
for each row
declare
v_count number;
begin
select count(1) into v_count from temp;
update temp set is_active=0 where is_active=1 and id=:new.id;
end;
/
select * from temp;
insert into temp values (1,'xyz',1);
insert into temp values (1,'xyz',1);
insert into temp select 1,'xyz',1 from dual;
getting an error while inserting using a query.
Mutating table occurs when we query the table which owns the trigger. Specifically it happens when Oracle can't guarantee the outcome of the query. Now when you insert a single row into the table Oracle can predict the outcome of the query when the FOR EACH ROW trigger fires, because it's a single row.
But with an INSERT FROM query Oracle is confused: should the count be the final figure including all the rows selected by the query or just a rolling count? The answer seems straightforward in this case but it's easy to imagine other queries where the answer is not clear cut. Rather than evaluate each query on its predictability Oracle enforces a plain fiat and hurls ORA-04091 for all query driven inserts.
The restriction on Mutating Tables applies to all triggers that use FOR EACH ROW clause except when either of the following is true:
the trigger fires on BEFORE event, i.e. the data wasn't actually changed
it is known that only one row will be affected - INSERT ... VALUES is the only DML that meets this condition
I have a table that collects logs of every check_in. I want to pick 4 columns to later process them. I have placed a trigger on every insert and columns are copied. I am confused over which way to do it. For best PERFORMANCE. Below are some different ways I figured out. Assuming my destination table is indexed.
ALTER trigger GetCheckIn_HA_Transit
on tableXyz
AFTER INSERT
as
declare #cardName nvarchar(max)
declare #checkIn datetime
declare #direction varchar(30)
declare #terminal varchar(30)
select
#direction = str_direction,
#terminal = TERMINAL,
#cardName = card_number,
#checkIn = transit_date
from tableXyz
GO
INSERT INTO logs(direction,terminal,cardName,checkIn)
VALUES
(#direction,#terminal,#cardName,#checkIn)
end
Another way i found was without declaration
ALTER trigger GetCheckIn_HA_Transit
on tableXyz
AFTER INSERT
as
GO
INSERT INTO
logs(direction,terminal,cardName,checkIn)
SELECT(STR_DIRECTION,TERMINAL,card_number,transit_date)FROM tableXyz
And is copying data from one table to another table is better in terms of performance than to copy from one database table to another database table over same server ??
Assuming every second we have an insert that will trigger our Trigger.
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 this table in an Oracle DB which has a primary key defined on 3 of the data columns. I want to drop the primary key constraint to allow rows with duplicate data for those columns, and create a new column, 'id', to contain an auto-incrementing integer ID for these rows. I know how to create a sequence and trigger to add an auto-incrementing ID for new rows added to the table, but is it possible to write a PL/SQL statement to add unique IDs to all the rows that are already in the table?
Once you have created the sequence:
update mytable
set id = mysequence.nextval;
If you're just using an integer for a sequence you could update the id with the rownum. e.g.
update
table
set id = rownum
You then need to reset the sequence to the next valid id.
Is this what you need?
UPDATE your_table
SET id = your_seq.nextval;
This assumes you don't care what order your primary keys are in.
First you should check your PCTFREE... is there enough room for every row to get longer?
If you chose a very small PCTFREE or your data has lots of lenght-increasing updates, you might begin chaining every row to do this as an update.
You almost certainly better to do this as a CTAS.
Create table t2 as select seq.nextval, t1.* from t1.
drop t1
rename t2 to t1.