I'm trying to create a trigger that updates a column in a table when other columns are updated. but getting the following error while saving the trigger
ORA-25000: invalid use of bind variable in trigger WHEN clause
My trigger is as follows, I'm not sure what is wrong with the code.
CREATE OR REPLACE TRIGGER Employees_ARIU
BEFORE INSERT OR UPDATE ON Employees
FOR EACH ROW
WHEN ((nvl(:OLD.EMP_SAL,0) != nvl(:NEW.EMP_SAL,0)) OR (nvl(:OLD.SAL_LEVEL,0) != nvl(:NEW.SAL_LEVEL,0)))
BEGIN
:NEW.LAST_UPDATED = SYSDATE
END;
Although IF is an alternative to WHEN, I'd say that it is better to use WHEN clause whenever possible because it is a
SQL condition that must be satisfied for the database to fire the trigger
So, why would you even let the trigger fire and then conclude that oh, OK, I don't want to do anything, after all? Better not running it at all!
Yes, WHEN clause has its restrictions and you can't put anything you want in there, but - your case isn't one of those.
(more info in Documentation, search for "WHEN clause").
So, for a sample table
SQL> create table employees
2 (id number,
3 emp_sal number,
4 sal_level number,
5 last_updated date);
Table created.
trigger would looks like this:
SQL> create or replace trigger employees_ariu
2 before insert or update on employees
3 for each row
4 when ( nvl(old.emp_sal, 0) <> nvl(new.emp_sal, 0)
5 or nvl(old.sal_level, 0) <> nvl(new.sal_level, 0)
6 )
7 begin
8 :new.last_updated := sysdate;
9 end;
10 /
Trigger created.
Testing:
SQL> insert into employees (id, emp_sal, sal_level) values (1, 100, 1);
1 row created.
SQL> select * from employees;
ID EMP_SAL SAL_LEVEL LAST_UPDATED
---------- ---------- ---------- -------------------
1 100 1 12.06.2021 12:14:17
SQL> update employees set sal_level = 2 where id = 1;
1 row updated.
SQL> select * from employees;
ID EMP_SAL SAL_LEVEL LAST_UPDATED
---------- ---------- ---------- -------------------
1 100 2 12.06.2021 12:14:33
SQL>
I think you can try updating your WHEN condition to IF statement along with few other changes -
CREATE OR REPLACE TRIGGER Employees_ARIU
BEFORE INSERT OR UPDATE ON Employees
FOR EACH ROW
BEGIN
IF ((nvl(:OLD.EMP_SAL,0) != nvl(:NEW.EMP_SAL,0)) OR (nvl(:OLD.SAL_LEVEL,0) != nvl(:NEW.SAL_LEVEL,0))) then
:NEW.LAST_UPDATED := SYSDATE;
END IF;
END;
/
Here is the fiddle.
Related
I have a table that has a bunch of columns, one of which is a 'last_update_time' column. Whenever I change the value of any of the other columns, I would like 'last_update_time' to automatically update to SYSDATE.
I know that you would usually use triggers for this kind of thing, but as far as I am aware it is not possible to have a trigger for a table mutate that same table.
What is the best way of implementing the functionallity described above?
You can use a trigger before update of. You only need to specify the columns that might be updated in the clause before of
Take a look at this
SQL> create table testtrg ( c1 number, c2 date ) ;
Table created.
SQL> create or replace trigger mytrig
before update of c1
on testtrg
referencing new as new old as old
for each row
declare
begin
:new.c2 := sysdate;
end;
/ 2 3 4 5 6 7 8 9 10 11 12 13
Trigger created.
SQL> select * from testtrg;
no rows selected
SQL> insert into testtrg values ( 1 , sysdate - 360 );
1 row created.
SQL> commit;
Commit complete.
SQL> select * from testtrg ;
C1 C2
---------- ---------
1 28-JUL-19
SQL> update testtrg set c1=2 ;
1 row updated.
SQL> commit ;
Commit complete.
SQL> select * from testtrg ;
C1 C2
---------- ---------
2 22-JUL-20
SQL>
In my tables I like to keep track of when it was created in addition to when it was last modified. My triggers look something like this:
CREATE OR REPLACE TRIGGER tnsnames.tns_server_override_trg
BEFORE INSERT OR UPDATE
ON "TNSNAMES".tns_server_override
FOR EACH ROW
BEGIN
:new.modified_dt := SYSDATE;
:new.modified_by := SYS_CONTEXT( 'USERENV', 'OS_USER' );
CASE
WHEN INSERTING
THEN
:new.created_dt := :new.modified_dt;
:new.created_by := :new.modified_by;
WHEN UPDATING
THEN
:new.created_dt := :old.created_dt;
:new.created_by := :old.created_by;
END CASE;
END;
How I do create column ID with value JASG1?
I am only find example like this :
select 'JASG'||to_char(mtj_id_seq.nextval) from talend_job
Although what you wrote probably works (if there's a sequence named MTJ_ID_SEQ, you have a privilege to select from it; the same goes for the TALEND_JOB table), I'd say that it isn't what you should use.
Here's why: I'll create a table and a sequence. Table will be pre-populated with some IDs (just to put something in there).
SQL> create sequence mtj_id_seq;
Sequence created.
SQL> create table talend_job as
2 select rownum id from dept;
Table created.
SQL> select * from talend_job;
ID
----------
1
2
3
4
OK; 4 rows so far. Now, run your SELECT:
SQL> select 'JASG'||to_char(mtj_id_seq.nextval) from talend_job;
'JASG'||TO_CHAR(MTJ_ID_SEQ.NEXTVAL)
--------------------------------------------
JASG1
JASG2
JASG3
JASG4
SQL> select 'JASG'||to_char(mtj_id_seq.nextval) from talend_job;
'JASG'||TO_CHAR(MTJ_ID_SEQ.NEXTVAL)
--------------------------------------------
JASG5
JASG6
JASG7
JASG8
SQL>
See? You didn't get only 1 JASGx value, but as many as number of rows in the TALEND_JOB table. If there was a million rows, you'd get a million JASGx rows as well.
Therefore, maybe you meant to use DUAL table instead? E.g.
SQL> select 'JASG'||to_char(mtj_id_seq.nextval) from dual;
'JASG'||TO_CHAR(MTJ_ID_SEQ.NEXTVAL)
--------------------------------------------
JASG9
SQL> select 'JASG'||to_char(mtj_id_seq.nextval) from dual;
'JASG'||TO_CHAR(MTJ_ID_SEQ.NEXTVAL)
--------------------------------------------
JASG10
SQL>
See? Only one value.
Also, notice that sequences will provide unique values, but you can't rely on them being gapless.
As you mentioned "how to create column ID" - one option is to use a trigger. Here's an example:
SQL> create table talend_job (id varchar2(20), name varchar2(20)
Table created.
SQL> create or replace trigger trg_bi_tj
2 before insert on talend_job
3 for each row
4 begin
5 :new.id := 'JASG' || mtj_id_seq.nextval;
6 end;
7 /
Trigger created.
Let's insert some names; IDs should be auto-populated by the trigger:
SQL> insert into talend_job (name) values ('littlefoot');
1 row created.
SQL> insert into talend_job (name) values ('Ishak');
1 row created.
SQL> select * From talend_job;
ID NAME
-------------------- --------------------
JASG11 littlefoot
JASG12 Ishak
SQL>
OK then; now you have some more info - read and think about it.
By the way, what is the "compiler-errors" tag used for? Did you write any code and it failed? Perhaps you'd want to share it with us.
I have a table named TABLE_1 which has 3 columns
row_id row_name row_descr
1 check1 checks here
2 check2 checks there
These rows are created through a front end application. Now suppose I delete the entry with row_name check2 from the front end and create another entry from front end with row_name check3, in database my entries will be as follows.
row_id row_name row_descr
1 check1 checks here
3 check3 checks
Now row_id if you observe is not a normal one time increment, Now my problem is i'm writing an insert statement to automate something and i don't know what i should insert in the row_id column. Previously i thought it is just new row_id = old row_id +1. But this is not the case here. Please help
EDIT :
Currently im inserting like this which is Wrong :
insert into TABLE1 (row_id, row_name, row_descr
) values ( (select max (row_id) + 1 from TABLE1),'check1','checks here');
row_id is not a normal one time increment.
Never ever calculate ids by max(id)+1 unless you can absolutly exclude simultaneous actions ( which is almost never ever the case). In oracle (pre version 12 see Kumars answer) create a sequence once and insert the values from that sequences afterwards.
create sequence my_sequence;
Either by a trigger which means you don't have to care about the ids during the insert at all:
CREATE OR REPLACE TRIGGER myTrigger
BEFORE INSERT ON TABLE1 FOR EACH ROW
BEGIN
SELECT my_sequence.NEXTVAL INTO :NEW.row_id FROM DUAL;
END;
/
Or directly with the insert
insert into TABLE1 (row_id, row_name, row_descr
) values ( my_sequence.nextval,'check1','checks here');
Besides using row_id as column name in oracle might be a little confusing, because of the pseudocolumn rowid which has a special meaning.
To anwser your quetstion though: If you really need to catch oracle errors as excpetions you can do this with PRAGMA EXCEPTION INIT by using a procedure for your inserts. It might look somehow like this:
CREATE OR REPLACE PROCEDURE myInsert( [...] )
IS
value_allready_exists EXCEPTION;
PRAGMA EXCEPTION_INIT ( value_allready_exists, -00001 );
--ORA-00001: unique constraint violated
BEGIN
/*
* Do your Insert here
*/
EXCEPTION
WHEN value_allready_exists THEN
/*
* Do what you think is necessary on your ORA-00001 here
*/
END myInsert;
Oracle 12c introduced IDENTITY columns. Precisely, Release 12.1. It is very handy with situations where you need to have a sequence for your primary key column.
For example,
SQL> DROP TABLE identity_tab PURGE;
Table dropped.
SQL>
SQL> CREATE TABLE identity_tab (
2 ID NUMBER GENERATED ALWAYS AS IDENTITY,
3 text VARCHAR2(10)
4 );
Table created.
SQL>
SQL> INSERT INTO identity_tab (text) VALUES ('Text');
1 row created.
SQL> DELETE FROM identity_tab WHERE ID = 1;
1 row deleted.
SQL> INSERT INTO identity_tab (text) VALUES ('Text');
1 row created.
SQL> INSERT INTO identity_tab (text) VALUES ('Text');
1 row created.
SQL> INSERT INTO identity_tab (text) VALUES ('Text');
1 row created.
SQL> DELETE FROM identity_tab WHERE ID = 2;
1 row deleted.
SQL> SELECT * FROM identity_tab;
ID TEXT
---------- ----------
3 Text
4 Text
SQL>
Now let's see what's under the hood -
SQL> SELECT table_name,
2 column_name,
3 generation_type,
4 identity_options
5 FROM all_tab_identity_cols
6 WHERE owner = 'LALIT'
7 /
TABLE_NAME COLUMN_NAME GENERATION IDENTITY_OPTIONS
-------------------- --------------- ---------- --------------------------------------------------
IDENTITY_TAB ID ALWAYS START WITH: 1, INCREMENT BY: 1, MAX_VALUE: 9999999
999999999999999999999, MIN_VALUE: 1, CYCLE_FLAG: N
, CACHE_SIZE: 20, ORDER_FLAG: N
SQL>
So, there you go. A sequence implicitly created by Oracle.
And don't forget, you can get rid off the sequence only with the purge option with table drop.
If you are not worried about which values are causing the error, then you could handle it by including a /*+ hint */ in the insert statement.
Here is an example where we would be selecting from another table, or perhaps an inner query, and inserting the results into a table called TABLE_NAME which has a unique constraint on a column called IDX_COL_NAME.
INSERT /*+ ignore_row_on_dupkey_index(TABLE_NAME(IDX_COL_NAME)) */
INTO TABLE_NAME(
INDEX_COL_NAME
, col_1
, col_2
, col_3
, ...
, col_n)
SELECT
INDEX_COL_NAME
, col_1
, col_2
, col_3
, ...
, col_n);
Oracle will blow past the redundant row. This is not a great solution if you care about know WHICH row is causing the issue, or anything else. But if you don't care about that and are fine just keeping the first value that was inserted, then this should do the job.
You can use an exception build in which will raise whenever there will be duplication on unique key
DECLARE
emp_count number;
BEGIN
select count(*) into emp_count from emp;
if emp_count < 1 then
insert into emp
values(1, 'First', 'CLERK', '7839', SYSDATE, 1200, null, 30);
dbms_output.put_line('Clerk added');
else
dbms_output.put_line('No data added');
end if;
EXCEPTION
when dup_val_on_index then
dbms_output.put_line('Tried to add row with duplicated index');
END;
I want to create a sequence for this varchar. It would have been easier had it been a number instead of varchar. In that case, I could do
seq_no := seq_no + 1;
But what can I do when I want to store next value in column as A0000002, when the previous value was A0000001 (to increment the number in the next varchar rowby 1)?
This can be done by
to_char(seq_no,'FM0000000')
your example can be done by creating sequence in oracle
create sequence seq_no start with 1 increment by 1;
then
select 'A'||to_char(seq_no.nextval,'FM0000000') from dual;
Right now i have used in dual ..but place this
'A'||to_char(seq_no.nextval,'FM0000000')
in your required query ..this will create sequence as you mentioned
sqlfiddle
Sequences are purely numeric. However, you need a trigger anyway, so simply adapt such trigger to insert the desired prefix:
CREATE OR REPLACE TRIGGER FOO_TRG1
BEFORE INSERT
ON FOO
REFERENCING NEW AS NEW OLD AS OLD
FOR EACH ROW
BEGIN
IF :NEW.FOO_ID IS NULL THEN
SELECT 'A' || TO_CHAR(FOO_SEQ1.NEXTVAL, 'FM0000000') INTO :NEW.FOO_ID FROM DUAL;
END IF;
END FOO_TRG1;
/
ALTER TRIGGER FOO_TRG1 ENABLE;
If you're able I'd actually use a virtual column as defined in the CREATE TABLE syntax. It makes it more easily extensible should the need arise.
Here's a working example.
SQL> create table tmp_test (
2 id number(7,0) primary key
3 , col1 number
4 , seq varchar2(8 char) generated always as (
5 'A' || to_char(id, 'FM0999999'))
6 );
Table created.
SQL>
SQL> create sequence tmp_test_seq;
Sequence created.
SQL>
SQL> create or replace trigger tmp_test_trigger
2 before insert on tmp_test
3 for each row
4 begin
5
6 :new.id := tmp_test_seq.nextval;
7 end;
8 /
Trigger created.
SQL> show errors
No errors.
SQL>
SQL> insert into tmp_test (col1)
2 values(1);
1 row created.
SQL>
SQL> select * from tmp_test;
ID COL1 SEQ
---------- ---------- --------------------------------
1 1 A0000001
Having said that; you would be better off if you did not do this unless you have an unbelievably pressing business need. There is little point to making life more difficult for yourself by prepending a constant value onto a number. As A will always be A it doesn't matter whether it's there or not.
If the format is always a letter followed by 7 digits you can do:
sequence = lpad(substr(sequence,2,7)+1,7,'0')
I have an oralcle SP forced on me that will not accept an empty parameter in an update. So if I wanted to set a value back to the default of ('') it will not let me pass in the empty string. Is there a keyword you can use such as default, null, etc that oracle would interpret back to the default specified for a particular column?
Sometimes things are just as simple as you hope they might be.
First, a table with a default value ...
SQL> create table t23 (
2 id number not null primary key
3 , col_d date default sysdate not null )
4 /
Table created.
SQL> insert into t23 values (1, trunc(sysdate, 'yyyy'))
2 /
1 row created.
SQL> select * from t23
2 /
ID COL_D
---------- ---------
1 01-JAN-10
SQL>
Next a procedure which updates the default column ...
SQL> create or replace procedure set_t23_date
2 ( p_id in t23.id%type
3 , p_date in t23.col_d%type )
4 is
5 begin
6 update t23
7 set col_d = p_date
8 where id = p_id;
9 end;
10 /
Procedure created.
SQL>
... but which doesn't work as we would like:
SQL> exec set_t23_date ( 1, null )
BEGIN set_t23_date ( 1, null ); END;
*
ERROR at line 1:
ORA-01407: cannot update ("APC"."T23"."COL_D") to NULL
ORA-06512: at "APC.SET_T23_DATE", line 6
ORA-06512: at line 1
SQL>
So, let's try adding a DEFAULT option ...
SQL> create or replace procedure set_t23_date
2 ( p_id in t23.id%type
3 , p_date in t23.col_d%type )
4 is
5 begin
6 if p_date is not null then
7 update t23
8 set col_d = p_date
9 where id = p_id;
10 else
11 update t23
12 set col_d = default
13 where id = p_id;
14 end if;
15 end;
16 /
Procedure created.
SQL>
... and lo!
SQL> exec set_t23_date ( 1, null )
PL/SQL procedure successfully completed.
SQL>
SQL> select * from t23
2 /
ID COL_D
---------- ---------
1 28-FEB-10
SQL>
I ran this example on an 11g database. I can't remember when Oracle introduced this exact support for DEFAULT, but it has been quite a while (9i???)
edit
The comments are really depressing. The entire point of building PL/SQL APIs is to make it easier for application developers to interact with the database. That includes being sensible enough to rewrite stored procedures when necessary. The big difference between building something out of software and, say, welding cast-iron girders together is that software is malleable and easy to change. Especially when the change doesn't alter the signature or behaviour of an existing procedure, which is the case here.
The procedure that's been forced on you:
create or replace procedure notEditable(varchar2 bar) as
begin
--update statement
null;
end;
How to use:
begin
notEditable(bar=>null);
end;
I didn't actually compile, but I believe this is the correct syntax.