I am using the following code for stopping null value insert into table using trigger. But when I pass null value, the inserting is happening fine. Any idea what am I doing wrong here?
create table test
(col1 number,
col2 varchar2(40)
)
create or replace trigger test_trg
after insert on test
for each row
declare
excp exception;
pragma autonomous_transaction;
begin
if :new.col2 is null then
RAISE excp;
end if;
exception
when excp then
dbms_output.put_line('error');
rollback;
end;
(Please note, I do accept that using a not null or a check constraint on the col2 is a better solution. I just want to find out the reason behind the error in this seemingly correct code)
Don't rollback in trigger, just re-raise excpetion after logging it:
create or replace trigger test_trg
after insert on test
for each row
declare
excp exception;
pragma autonomous_transaction;
begin
if :new.col2 is null then
RAISE excp;
end if;
exception
when excp then
dbms_output.put_line('error');
raise; -- propagate error
end;
When you put "exception ... end;" block in code you say to PL/SQL that managing consequences of this error is on your responsibility. So, if you don't raise any error from a code which handles original error, for PL/SQL it means that all actions regarding this error already done in your code, all went OK and record must be inserted.
You can try it in this SQLFiddle.
you have to define the trigger as BEFORE INSERT to fire before the insert is executed, remove the pragma autonomouse_transaction and the rollback (they have no sense here, because you do not any DML), then reraise the exception in the exception handler
Related
I need to update some code which uses dynamic sql and potentially could have duplicate column names in the columns of the insert statement.
So I wanted to handle this, ORA-00957: Duplicate Column name. This error does not get handled by the most generic "when others" in the exception block. If I make it test a unique constraint violation it does.
Following some test code:
create table animal (id number , animal_type number,
animal_name varchar2(20), constraint id primary key(id));
-----------------------------------------------------
begin
for i in 1.. 100 loop
insert into animal(id, animal_type, animal_name)
values(i,floor(dbms_random.value(1,30)),'animal'||i);
end loop;
end;
-----------------------------------------------------
DECLARE
-- e_duplicate_column exception;
-- pragma exception_init(e_duplicate_column,-957);
BEGIN
insert into animal(id, animal_name, animal_name)
values(1000003, 'animal 1000003', 'animal 1000003');
EXCEPTION
WHEN OTHERS THEN
dbms_output.put_line(SQLCODE);
dbms_output.put_line(SQLERRM);
END;
I was trying to get the codes here as the pragma wasn't working(i.e. arriving) either. But that's not happening if it doesn't even get to "when others".
Any insights are appreciated.
Cheers, Robbert
PS oracle 12C, tried on sqldeveloper and toad
Your test code does not use dynamic SQL, which is required to generate an ORA-00957 error. Without dynamic SQL, Oracle will throw the ORA-00957 when it compiles your block, which I think you are misinterpreting as Oracle actually running you block and skipping the exception handler.
Try this instead as a test (make sure you have DBMS output enabled in your client!):
DECLARE
-- e_duplicate_column exception;
-- pragma exception_init(e_duplicate_column,-957);
BEGIN
execute immediate q'[insert into animal(id, animal_name, animal_name) values(1000003, 'animal 1000003', 'animal 1000003')]';
EXCEPTION
WHEN OTHERS THEN
dbms_output.put_line(SQLCODE);
dbms_output.put_line(SQLERRM);
END;
-957
ORA-00957: duplicate column name
Exception
WHEN OTHERS THEN
--dbms_output.put_line('pl_update_sidm_user r: ERROR CODE:' || sqlcode || '~' ||
--sqlerrm || ' EMPL_NBR:' || r.EMPL_NBR);
insert into ERROR_MSG (ERROR_MSG_ID,ERROR_MSG) values (ERROR_MSG_ID_SEQ.NEXTVAL, 'pl_update_sidm_user_duty_role r2');
END;
I would like to put the error result to a table.
However, how can I do that?
Can I put the result of dbms_output to a table as a string?
If not, can I get the sqlcode,sqlerrm without using dbms_output?
Thank you !!
From the documentation,
A SQL statement cannot invoke SQLCODE or SQLERRM. To use their values
in a SQL statement, assign them to local variables first
Also,
Oracle recommends using DBMS_UTILITY.FORMAT_ERROR_STACK except when using the FORALL statement with its SAVE EXCEPTIONS clause
So, for SQLCODE or SQLERRM, you should assign them into variables and use them.
DECLARE
v_errcode NUMBER;
v_errmsg VARCHAR2(1000);
BEGIN
--some other statements that may raise exception.
EXCEPTION
WHEN OTHERS THEN
v_errcode := SQLCODE;
v_errmsg := SQLERRM;
insert into ERROR_TABLE (ERROR_MSG_ID,ERROR_MSG) --change your table name
values (ERROR_MSG_ID_SEQ.NEXTVAL,
v_errcode||':'||v_errmsg);
END;
/
Preferably use insert like this instead, as per Oracle's recommendation.
insert into ERROR_TABLE (ERROR_MSG_ID,ERROR_MSG) values (ERROR_MSG_ID_SEQ.NEXTVAL,
DBMS_UTILITY.FORMAT_ERROR_STACK);
Demo
Technically what others are suggesting is correct: the "insert" operation executed in the "exception when others" block will actually insert a new row in the log table.
the problem is that such insert statement will be part of the same transaction of the main procedure and, since you had an error while executing it, you are very likely to rollback that transaction, and this will rollback also the insert in your log table
I suppose the problem you are facing is not that you aren't successfully logging the error message: it is that you are rolling it back immediately afterwards, along with all the other writes you did in the same transaction.
Oracle gives you a way of executing code in a SEPARATE transaction, by using "autonomous transaction" procedures.
you need to create such a procedure:
create or replace procedure Write_Error_log(
arg_error_code number,
arg_error_msg varchar2,
arg_error_backtrace varchar2) is
PRAGMA AUTONOMOUS_TRANSACTION;
begin
INSERT INTO error_msg (
error_msg_id,
error_code,
error_msg,
error_stack)
VALUES (
error_msg_id_seq.NEXTVAL,
arg_error_code,
arg_error_msg,
arg_error_backtrace);
commit; -- you have to commit or rollback always, before exiting a
-- pragma autonomous_transaction procedure
end;
What this procedure does is to write a new record in the log table using a totally separate and independent transaction: the data will stay in the log table even if you execute a roll back in your calling procedure. You can also use such a procedure to create a generic log (not only errors).
All you have to do now is to call the procedure above whenever you need to log something, so your code becomes:
DECLARE
v_errcode NUMBER;
v_errmsg VARCHAR2(1000);
BEGIN
--some other statements that may raise exception.
EXCEPTION WHEN OTHERS THEN
Write_Error_log(SQLCODE, SQLERRM, dbms_utility.format_error_backtrace);
END;
/
P.S: there might be some typos in my code: I can't test it right now since I can't reach an oracle server in this moment.
I'm working on the following PL/SQL trigger:
CREATE OR REPLACE TRIGGER trigger_1
BEFORE UPDATE ON worker
FOR EACH ROW
DECLARE
BEGIN
IF :OLD.type = 'PRESIDENT' THEN
INSERT INTO trigger_log VALUES (sysdate, 'Nope.', 'No change.');
RAISE_APPLICATION_ERROR(-20111, 'Can not change!');
END IF;
END;
Here, I want to cancel the UPDATE command on the worker table, when a PRESIDENT's payment is about to get changed. At the same time, I wish to log this command into table called trigger_log. The problem is, when I RAISE_APPLICATION_ERROR the UPDATE got cancelled, but the logging (INSERT INTO trigger_log) aswell. How can I RAISE_APPLICATION_ERROR or throw an EXCEPTION, but still have all commands to be run inside the TRIGGER?
You have to commit your INSERT-Statement before raising the error.
Maybe think about AUTONOMOUS_TRANSACTION
EDIT
As others have stated already, you should not and cannot commit inside a trigger (exception autonomous transaction). So think about using the solution of Tom Thomas or calling a logging-procedure/-package.
You can call a stored procedure from your trigger. That stored procedure should be declared as PRAGMA AUTONOMOUS_TRANSACTION. Try like this,
CREATE OR REPLACE
PROCEDURE log_error_p
AS
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
INSERT INTO trigger_log VALUES (SYSDATE, 'Nope.', 'No change.');
COMMIT;
END;
--
CREATE OR REPLACE TRIGGER trigger_1
BEFORE UPDATE ON worker
FOR EACH ROW
DECLARE
BEGIN
IF :OLD.TYPE = 'PRESIDENT' THEN
log_error_p();
RAISE_APPLICATION_ERROR(-20111, 'Can not change!');
END IF;
END;
/
First of all, never use a commit or a rollback inside the trigger. It's a coding standard. As for your question i think this is a better way than raise_application_error
CREATE OR REPLACE TRIGGER trigger_1
BEFORE UPDATE ON worker
REFERENCING OLD as o AND NEW as n
FOR EACH ROW
DECLARE
InsertException EXCEPTION;
BEGIN
IF o.TYPE = 'PRESIDENT' THEN
RAISE InsertException;
END IF;
EXCEPTION
WHEN InsertException THEN
INSERT INTO trigger_log VALUES (SYSDATE, 'Nope.', 'No change.');
DBMS_OUTPUT.PUT_LINE(SQLERRM);
END;
/
I have the following code in a package which inserts data into table.
I am able to get parent key not found exception. How can I specifically get constraint violated message for each column? E.g. if proj_id is violated then raise exception, if proj_code is violated, then raise another exception.
PROCEDURE add_project(
p_proj_id project.proj_id%TYPE,
p_proj_desc project.proj_desc%TYPE,
p_proj_code project.proj_code%TYPE,
p_proj_date project.proj_date%TYPE
)
IS
parent_not_found exception;
pragma exception_init(parent_not_found, -2291);
BEGIN
INSERT
INTO projects (proj_id,proj_desc,proj_code,proj_date) values
(p_proj_id,p_proj_desc,p_proj_code,p_proj_date);
exception
when parent_not_found then
raise_application_error(-20001,'Invalid');
END;
Take a look at EXCEPTION_INIT Pragma.
DECLARE
l_parentnotfound exception;
l_res integer;
PRAGMA EXCEPTION_INIT(l_parentnotfound, -2291);
BEGIN
-- check if the parent key exists
select 1 into l_res from codes where code = proj_code;
-- if not, raise exception
if l_res <> 1 then
raise l_parentnotfound;
end if;
INSERT INTO projects (proj_id,proj_desc,proj_code,proj_date) values (p_proj_id,p_proj_desc,p_proj_code,p_proj_date);
EXCEPTION WHEN l_parentnotfound THEN
-- handle the error
END;
Or you can use WHEN OTHERS and look for the SQLCODE.
EDIT:
Note that you are not forced to manually check that the parent key exists to raise the exception, you can stay with :
DECLARE
l_parentnotfound exception;
l_res integer;
PRAGMA EXCEPTION_INIT(l_parentnotfound, -2291);
BEGIN
INSERT INTO projects (proj_id,proj_desc,proj_code,proj_date) values (p_proj_id,p_proj_desc,p_proj_code,p_proj_date);
EXCEPTION WHEN l_parentnotfound THEN
-- handle the error
END;
But if you want to be able to get violated constraint name easily, it can be useful to raise exception manually for each column. Also you can try to get the constraint name using USER_CONSTRAINTS and USER_CONS_COLUMNS.
Another way to get the violated constraint name is to parse the SQLERRM error message.
try
create PROCEDURE add_project(p_proj_id project.proj_id%TYPE,
p_proj_desc project.proj_desc%TYPE,
p_proj_code project.proj_code%TYPE,
p_proj_date project.proj_date%TYPE) IS
BEGIN
INSERT INTO projects
(proj_id, proj_desc, proj_code, proj_date)
values
(p_proj_id, p_proj_desc, p_proj_code, p_proj_date);
--add this
EXCEPTION
WHEN OTHERS THEN
ROLLBACK;
END;
I need to handle the ORA-01400 error (cannot insert NULL into ("SCHEMA"."TABLE_NAME"."COLUMN_NAME") ) using a exception handle.
ORACLE Predefine a few Exceptions like (ACCESS_INTO_NULL, ZERO_DIVIDE and so on), but apparently does not define an Exception for the ORA-01400 error, how do I handle this particular error code?
I need something like this (other suggestions are accepted).
....
...
INSERT INTO MY_TABLE (CODE, NAME) VALUES (aCode,aName);
COMMIT;
EXCEPTION
WHEN NULL_VALUES THEN /* i don't know this value , exist?*/
Do_MyStuff();
WHEN OTHERS THEN
raise_application_error(SQLCODE,MY_OWN_FORMAT_EXCEPTION(SQLCODE,SQLERRM),TRUE);
END;
The pre-defined PL/SQL exceptions are special to Oracle. You really can't mess with those. When you want to have a set of predefined exceptions of your own you can't declare them "globally" like the standard ones. Instead, create an exceptions package which has all of the exception declarations and use that in your application code.
Example:
CREATE OR REPLACE PACKAGE my_exceptions
AS
insert_null_into_notnull EXCEPTION;
PRAGMA EXCEPTION_INIT(insert_null_into_notnull, -1400);
update_null_to_notnull EXCEPTION;
PRAGMA EXCEPTION_INIT(update_null_to_notnull, -1407);
END my_exceptions;
/
Now use the exception defined in the package
CREATE OR REPLACE PROCEDURE use_an_exception AS
BEGIN
-- application specific code ...
NULL;
EXCEPTION
WHEN my_exceptions.insert_null_into_notnull THEN
-- application specific handling for ORA-01400: cannot insert NULL into (%s)
RAISE;
END;
/
Source: http://www.orafaq.com/wiki/Exception
you can define your own exceptions, like variables (they will have the same scope as other variables so you can define package exception, etc...):
SQL> DECLARE
2 NULL_VALUES EXCEPTION;
3 PRAGMA EXCEPTION_INIT(NULL_VALUES, -1400);
4 BEGIN
5 INSERT INTO t VALUES (NULL);
6 EXCEPTION
7 WHEN null_values THEN
8 dbms_output.put_line('null value not authorized');
9 END;
10 /
null value not authorized
PL/SQL procedure successfully completed
You can handle exception by its code like this:
....
...
INSERT INTO MY_TABLE (CODE, NAME) VALUES (aCode,aName);
COMMIT;
EXCEPTION
WHEN OTHERS THEN
IF SQLCODE = -1400 THEN
Do_MyStuff();
ELSE
raise_application_error(SQLCODE,MY_OWN_FORMAT_EXCEPTION(SQLCODE,SQLERRM),TRUE);
END IF;
END;
INSERT INTO MY_TABLE (CODE, NAME) VALUES (aCode,aName);
COMMIT;
EXCEPTION
WHEN NULL_VALUES /* i don't know this value , exist?*/
emesg := SQLERRM;
dbms_output.put_line(emesg);
WHEN OTHERS THEN
emesg := SQLERRM;
dbms_output.put_line(emesg);
END;
SQLERRM shows the sql error message
http://www.psoug.org/reference/exception_handling.html