Handle ORACLE Exceptions - oracle

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

Related

oracle exception not going to exception block

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

Trigger not working for stopping table insert

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

What PRAGMA statements would be used inside an EXCEPTION block?

I was playing around with Oracle exceptions and tried to do some preprocessing between EXCEPTION and the WHERE statements. That is,
EXCEPTION
some_operation_here();
WHEN yaddayadda THEN
...
PL/SQL Developer said that that wasn't kosher – oh well – but its error message intrigued me: it was expecting either WHEN or PRAGMA. I am not thoroughly familiar with all the PRAGMA directives, but it doesn't seem like any of them are applicable in an exception block unless for some reason you waited till this point to bind an error code to an exception you had declared earlier. Why would you ever need to use a PRAGMA directive here?
A little experimentation tells me that you can, in fact put a PRAGMA in the exception block, but I can't see much use to it. The following executes successfully, but the raised error triggers the OTHER section, not the section for the newly defined exception (e.g. it returns "Old exception"). It would appear that this is an undocumented feature.
DECLARE
v NUMBER;
new_divide_zero EXCEPTION;
BEGIN
v := 1 / 0;
EXCEPTION
PRAGMA EXCEPTION_INIT (new_divide_zero, -1476);
WHEN new_divide_zero THEN
DBMS_OUTPUT.put_line ('New exception');
WHEN OTHERS THEN
DBMS_OUTPUT.put_line ('Old exception');
END;
Similarly, I tried putting a AUTONOMOUS_TRANSACTION in the exception block, but it too appears to have no effect (in this case, both rows are inserted).
CREATE TABLE test_results (result VARCHAR2 (2000));
BEGIN
DECLARE
v NUMBER;
new_divide_zero EXCEPTION;
BEGIN
insert into test_results values ('Test Value');
v := 1 / 0;
EXCEPTION
PRAGMA AUTONOMOUS_TRANSACTION;
WHEN OTHERS THEN
INSERT INTO test_results
VALUES ('Old exception');
Commit;
END;
ROLLBACK;
END;
The Oracle documentation (12g, which is the version i tested this on) does not mention using PRAGMA in the exception block, so it's definitely undocumented. On the other hand, it doesn't seem to be much of a feature, as it doesn't appear to actually do anything...
WHEN { exception_name [ OR exception_name ]... | OTHERS } THEN
statement [ statement ]...
It is syntax error. To catch exception you must use following syntax:
declare
yaddayadda exception;
begin
...
exception
WHEN yaddayadda THEN
some_operation_here();
end;
You need to use pragma exception_Init to assign you custom exception with sql error code.
For example:
declre
l_id number;
e_resource_busy EXCEPTION;
PRAGMA EXCEPTION_INIT(e_resource_busy, -54);
begin
select id
into l_id
from job_table
where status = 'RUNNING'
for update nowait;
exception
WHEN e_resource_busy THEN
-- row is locked
some_operation_here();
end;

Raise parent key integrity constraint in procedure for each column

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;

Customize PL/SQL exceptions in Oracle

Frequently I found myself doing some functions to insert/delete/update in one or more tables and I've seen some expected exceptions been taken care of, like no_data_found, dupl_val_on_index, etc. For an insert like this:
create or replace FUNCTION "INSERT_PRODUCTS" (
a_supplier_id IN FORNECEDOR.ID_FORNECEDOR%TYPE,
a_prodArray IN OUT PRODTABLE
)
RETURN NUMBER IS
v_error_code NUMBER;
v_error_message VARCHAR2(255);
v_result NUMBER:= 0;
v_prod_id PRODUTO.ID_PROD%TYPE;
v_supplier FORNECEDOR%ROWTYPE;
v_prodInserted PROD_OBJ;
newList prodtable := prodtable();
BEGIN
SELECT FORNEC_OBJ(ID_FORNECEDOR,NOME_FORNECEDOR,MORADA,ARMAZEM,EMAIL,TLF,TLM,FAX) into v_supplier from fornecedor where id_fornecedor = a_supplier_id;
FOR i IN a_prodArray.FIRST .. a_prodArray.LAST LOOP
INSERT INTO PRODUTO (PRODUTO.ID_PROD,PRODUTO.NOME_PROD,PRODUTO.PREC_COMPRA_PROD,PRODUTO.IVA_PROD,PRODUTO.PREC_VENDA_PROD,PRODUTO.QTD_STOCK_PROD,PRODUTO.QTD_STOCK_MIN_PROD)
VALUES (S_PRODUTO.nextval,a_prodArray(i).NOME_PROD,a_prodArray(i).PREC_COMPRA_PROD,a_prodArray(i).IVA_PROD,NULL,NULL,NULL);
/* If the above insert didn't failed, we can insert in weak entity PROD_FORNECIDO. */
SELECT ID_PROD into v_prod_id from PRODUTO where NOME_PROD = a_prodArray(i).NOME_PROD;
INSERT INTO PROD_FORNECIDO VALUES (a_supplier_id, v_prod_id,a_prodArray(i).PREC_COMPRA_PROD);
SELECT PROD_OBJ(ID_PROD,NOME_PROD,PREC_COMPRA_PROD,PREC_VENDA_PROD,QTD_STOCK_PROD,QTD_STOCK_MIN_PROD,IVA_PROD) into v_prodInserted from PRODUTO where ID_PROD= v_prod_id;
a_prodarray(i).ID_PROD := v_prod_id;
END LOOP;
INSERT INTO FORNECPRODS VALUES (a_supplier_id,v_supplier, a_prodarray);
v_result:= 1;
RETURN v_result;
COMMIT;
Exception
When no_data_found then
v_error_code := 0;
v_error_message:= 'Insert Products: One of selects returned nothing';
Insert Into errors Values (v_error_code,v_error_message, systimestamp);
RETURN v_result;
When others Then
ROLLBACK;
v_error_code := SQLCODE;
v_error_message:=substr(SQLERRM,1,50);
Insert Into errors Values (v_error_code,'Error inserting products list',systimestamp);
RETURN v_result;
END;
I would like to customize more of my exceptions or do an exception block for each select/insert. Is that possible or correct?
If so, could please show me some code with important exceptions being throwed by this function?
If you just want to substitute your own error message, there is RAISE_APPLICATION_ERROR...
When no_data_found then
RAISE_APPLICATION_ERROR(-20000
, 'Insert Products: One of selects returned nothing';
, true);
The third parameter returns the original error as well as your custom one.
Oracle also gives us the option to define our exceptions. This can be useful if we want to pass the exception to a calling program...
Declare
no_product_found exception;
Begin
....
When no_data_found then
raise no_product_found;
This would be most effective if we defined the NO_PRODUCT_FOUND exception in a package specification where it could be referenced by external program units.
In addition, Oracle provides the INIT_EXCEPTION pragma which allows us to associate Oracle error numbers with our custom exceptions. Unfortunately we cannot overload error numbers which Oracle has already defined (for instance, we cannot create our own exceptions for ORA-1403 which is already covered by the NO_DATA_FOUND exception). Find out more.
In the exception section; you can raise application error or return 0 with error code explanation. It is about your choice.
If you want to log your errors in the exception section (or in main section), write your own logging procedure with AUTONOMOUS TRANSACTION. so, your logging mechanism is not affected by your main transaction's COMMIT or ROLLBACK. (see: http://www.dba-oracle.com/t_autonomous_transaction.htm)
Another logging mechanism (DML Error Log) in Oracle 10gR2 (and above) is LOG ERRORS clause (see: http://www.oracle-base.com/articles/10g/DmlErrorLogging_10gR2.php).

Resources