I want to know if there is any way in oracle to redirect the control from exception block to the current begin/end block.
Following is the code snippet. i variable loops through the table data sets, I want to update table i; if there is any exception go to the exec1 exception block,do the stuff and then try updating table i again.
If control goes to the exec2 exception then continue to the next iteration.
I want help as after performing steps in exec1 exception, how can I try updating table(i) again; so that if it fails again it is handled in exec1 exception block.
FOR i in c_tables
LOOP
BEGIN
---label---
Update (i);
DBMS_OUTPUT.PUT_LINE ('ROWS UPDATED IS: ' || SQL%ROWCOUNT);
EXCEPTION
WHEN exec1 THEN
BEGIN
do_stuff();
goto label;
EXCEPTION WHEN exec2 THEN
do_stuff();
continue;
END;
END;
END LOOP;
I tried to simulate what you have, in Scott's schema.
It seems that you'd be good if you moved the label in front of the BEGIN, not after it. Have a look:
SQL> DECLARE
2 l_deptno_dflt NUMBER := 50;
3 BEGIN
4 FOR i IN (SELECT distinct deptno FROM emp)
5 LOOP
6 <<this_is_label>> -- put label here ...
7 BEGIN
8 -- <<this_is_label>> -- ... not here
9 UPDATE emp
10 SET deptno = l_deptno_dflt
11 WHERE deptno = i.deptno;
12
13 DBMS_OUTPUT.put_line ('rows updated is ' || SQL%ROWCOUNT);
14 EXCEPTION
15 WHEN OTHERS
16 THEN
17 DBMS_OUTPUT.put_line ('this is exec1');
18
19 BEGIN
20 l_deptno_dflt := 40;
21 goto this_is_label;
22 END;
23 END;
24 END LOOP;
25 END;
26 /
this is exec1
rows updated is 6
rows updated is 5
rows updated is 3
PL/SQL procedure successfully completed.
SQL>
If it is where you initially put it, it raises the mentioned PLS-00375 error.
Related
I was wondering if theres a way in which I can decide that from "this day on" a user-defined error can act as a resource I can use over and over.
For example->
Raise_Application_Error (-20343, 'The balance is too low.');
So basically if I can use -20343 as key word(error code) and use again in a different procedure instead of raising it again and again..,
Is that possible?
Well, you'll have to raise it, somehow, Oracle can't know what you want to do if balance is too low.
Maybe you could create your own table of exceptions, e.g.
SQL> select * from my_exception;
ERR_CODE ERR_NAM ERR_MESSAGE
---------- ------- ------------------------------
-20343 bal_low Balance is too low
-20344 name_s Name can not begin with an "S"
Function accepts error code and returns message:
SQL> create or replace function f_myerr (par_err_code in my_exception.err_code%type)
2 return my_exception.err_message%type
3 is
4 retval my_exception.err_message%type;
5 begin
6 select err_message
7 into retval
8 from my_exception
9 where err_code = par_err_code;
10 return retval;
11 exception
12 when no_data_found then
13 return 'Exception does not exist';
14 end;
15 /
Function created.
This piece of code simulates "balance too low" error:
SQL> declare
2 l_balance number;
3 bal_low exception;
4 begin
5 select sal into l_balance
6 from emp
7 where ename = 'JONES';
8
9 if l_balance < 5000 then
10 raise bal_low;
11 end if;
12
13 exception
14 when bal_low then
15 raise_application_error(-20343, f_myerr(-20343));
16 end;
17 /
declare
*
ERROR at line 1:
ORA-20343: Balance is too low
ORA-06512: at line 15
SQL>
Another PL/SQL procedure might also find out that balance is too low, but you'd have to repeat such a code again, I'm afraid.
You can modify that code (i.e. table, function) to better suit your needs, but - that's what I understood for what you said so far.
So,I am working with a cursor,the cursor was initially operating with the initial for loop,now i needed to perform operation if the no of records in the cursor is more than one,so i fetched the no of records first and stored in a variable and used an if-condition based on that.Now the problem is when I run the whole process,the procedure does its job,but only for the first record in the cursor and entirely skips the second record.Please suggest or help me identify the mistake.
Adding code snippet.
for m in get_m_p(a,b)--main cursor
loop
fetch get_m_p into c_m;
exit when g_m_p%notfound;
end loop;
tempcount := g_m_p%ROWCOUNT:
statements---
if(tempcount>1) then
statements----
end if;
end loop;
for the two records the main curosr is returning in first line,operations are only done for the first one,and the second record is being skipped entirely.
This is a superfluous line:
fetch get_m_p into c_m;
You don't explicitly fetch within a cursor FOR loop, it is implicitly done in each loop iteration. Remove that line.
How to get number of rows returned by a cursor? Lucky you, it seems that you don't care whether how many rows - exactly - it returns. All you want to know is whether it returned more than 1 row. So, count them, literally; exit the loop if counter exceeds 1.
SQL> DECLARE
2 CURSOR get_m_p IS
3 SELECT *
4 FROM emp
5 WHERE deptno = 10;
6
7 l_cnt NUMBER := 0;
8 BEGIN
9 FOR m IN get_m_p
10 LOOP
11 l_cnt := l_cnt + 1;
12 EXIT WHEN l_cnt > 1;
13 END LOOP;
14
15 DBMS_OUTPUT.put_line ('Cursor returned at least ' || l_cnt || ' row(s)');
16
17 IF l_cnt > 1
18 THEN
19 NULL;
20 -- the rest of statements go here
21 END IF;
22 END;
23 /
Cursor returned at least 2 row(s)
PL/SQL procedure successfully completed.
SQL>
As there's no way to know how many rows will cursor return, unfortunately, you'll have to check that first, and then decide what to do with the result.
DECLARE
CURSOR get_m_p IS
SELECT *
FROM emp
WHERE deptno = 10;
l_cnt NUMBER := 0;
BEGIN
SELECT COUNT (*)
INTO l_cnt
FROM (-- this is cursor's SELECT statement
SELECT *
FROM emp
WHERE deptno = 10);
FOR m IN get_m_p
LOOP
-- some statements here
IF l_cnt > 1
THEN
NULL;
-- statements to be executed if cursor return more than 1 row
END IF;
END LOOP;
END;
/
Cursor:
Oracle creates memory area to process SQL statement which is called context area and the cursor is pointer to the context area. A cursor holds the rows (one or more) returned by a SQL statement. The set of rows the cursor holds is referred to as the active set.
There are two type of cursor
1. Implicit cursor
2. Explicit cursor
Implicit Cursors :
Implicit cursors are automatically created by Oracle whenever an SQL statement is executed. Any SQL cursor attribute will be accessed as sql%attribute_name as shown below in the example. Use the SQL%ROWCOUNT attribute to determine the number of rows affected
DECLARE
no_of_records number(2);
BEGIN
select * from records;
IF sql%notfound THEN
dbms_output.put_line('no records present');
ELSIF sql%found THEN
no_of_records := sql%rowcount;
IF no_of_records > 1 THEN
dbms_output.put_line('no of records ' || no_of_records);
END IF
END IF;
END;
Explicit Cursors :
Explicit cursors are programmer-defined cursors for gaining more control over the context area. An explicit cursor should be defined in the declaration section of the PL/SQL Block. It is created on a SELECT Statement which returns more than one row.
Please see below example:
DECLARE
r_id records.id%type;
CURSOR c_records is
SELECT id FROM records;
BEGIN
OPEN c_records;
LOOP
FETCH c_records into r_id;
EXIT WHEN c_records%notfound;
dbms_output.put_line('Record id ' || r_id );
END LOOP;
CLOSE c_records;
END;
Reference :
https://www.tutorialspoint.com/plsql/plsql_cursors.htm
As an alternative you can cache every row and process after.
Example using sample schema "HR" on Oracle 11g Express Edition:
DECLARE
CURSOR get_m_p
IS
SELECT *
FROM hr.employees
WHERE department_id = 60
order by employee_id;
--
rcEmp_last get_m_p%rowtype;
l_cnt NUMBER;
BEGIN
FOR rcM IN get_m_p LOOP
l_cnt := get_m_p%rowcount;
Dbms_Output.Put_Line('l_cnt='||l_cnt);
if l_cnt=1 then
rcEmp_last:=rcM;
Else
Dbms_Output.Put_Line('Process='||to_char(l_cnt-1));
Dbms_Output.Put_Line('rcEmp_last.employee_id='||rcEmp_last.employee_id);
--
rcEmp_last:=rcM;
END IF;
End loop;
--
Dbms_Output.Put_Line('Exited FOR-LOOP');
Dbms_Output.Put_Line('l_cnt='||l_cnt);
--
if l_cnt>1 then
Dbms_Output.Put_Line('rcEmp_last.employee_id='||rcEmp_last.employee_id);
End if;
END;
Output:
Text
PL/SQL block, executed in 1 ms
l_cnt=1
l_cnt=2
Process=1
rcEmp_last.employee_id=103
l_cnt=3
Process=2
rcEmp_last.employee_id=104
l_cnt=4
Process=3
rcEmp_last.employee_id=105
l_cnt=5
Process=4
rcEmp_last.employee_id=106
Exited FOR-LOOP
l_cnt=5
rcEmp_last.employee_id=107
Total execution time 35 ms
I am new to PL/SQL. What is the difference between the below two flows?
BEGIN followed by IF
BEGIN
IF flag= 1 THEN
FOR SOME_REC(id)
LOOP
END LOOP;
END IF;
END
IF followed by BEGIN
IF flag= 1 THEN
BEGIN
FOR SOME_REC(id)
LOOP
END LOOP;
END
END IF;
By its design PL/SQL is a block structured language with each block consisting of 4 components:
Declaration Section - optional:; DECLARE or Named Block (Function, Procedure, ...)
Execution Section - required: BEGIN
Exception Section - optional: EXCEPTION
End Statement - required: END
As #Mr.AF indicates each block defines the SCOPE of variables. Further these blocks can be nested. So a variable declared in an outer block is visible within that block and all blocks nested within. Subject to the rule that closest declaration wins and items declared in an nested bloc are not visible in outer blocks. See GURU99 for fuller description. Try the following.
declare
var varchar2(5) := '12345';
begin
dbms_output.put_line ( 'Outer block has variable ''var'' and has a length of '
|| to_char(length(var)) || ' and value of ' || var);
declare -- start nested block
var varchar2(8);
inner_only varchar2(8) := 'ShotTerm';
begin
var := '12345678';
dbms_output.put_line ( 'Inner block has variable ''var'' and has a length of '
|| to_char(length(var)) || ' and value of ' || var
|| ' and also variable inner_only with value ' || inner_only);
end ; -- end nested block
dbms_output.put_line ( 'Outer block variable ''var'' still has a length of '
|| to_char(length(var)) || ' and value of ' || var);
-- uncomment below to see difference
-- dbms_output_put_line('A reference to ' || inner_only || ' does not work; gives compile error');
end ; --outer block
For your specific scenarios #1 the IF and LOOP are being run in an outer (or only) block. While #2 the IF is run in the outer block while the loop runs in an inner block. Note: #2 must have a prior BEGIN and the END IF must be followed by an END - without them you will get a compile syntax error.
BEGIN ... END keywords implies starting point and end point of a code block like { } and compiler will validate local references (locality of references) within the block.otherwise, unexpected results may be happened.
The way you put it, without any further explanation of what problem you are trying to solve (if any), then there's no much difference in those two pieces of code. Both will do what they are supposed to do.
However, I'd like to say something about the 3rd case you never mentioned: BEGIN-EXCEPTION-END block within the loop, which does make the difference.
IF flag = 1 THEN
FOR SOME_REC(id) LOOP
BEGIN
do_something_here;
EXCEPTION
when some exception then
handle it
END;
END LOOP;
END IF;
What would be its purpose? In both of your examples, if any exception occurs within the loop, processing will be stopped and the procedure will terminate.
But, if there's an inner begin-exception-end block, it lets you capture an error within the loop, handle it the way you find the most appropriate (if there's nothing better, just log the error) and move on to the next loop cycle.
Doing so, you'll be able to process all records returned by the cursor. Some of them might fail, that's true, but you'll be able to proceed with the execution.
Here's an example based on Scott's EMP table; I'll try to divide SAL and NVL(COMM, 0) which will result in divide by zero error in some cases.
SQL> select ename, sal, nvl(comm, 0) comm from emp where deptno = 30 order by ename;
ENAME SAL COMM
---------- ---------- ----------
ALLEN 1600 300
BLAKE 2850 0 --> 2850/0 --> error
JAMES 950 0 --> error
MARTIN 1250 1400
TURNER 1500 0 --> error
WARD 1250 500
6 rows selected.
Code, as you wrote it:
SQL> set serveroutput on
SQL> declare
2 l_divided number;
3 begin
4 for cur_r in (select ename, sal, nvl(comm, 0) comm
5 from emp
6 where deptno = 30
7 order by ename
8 )
9 loop
10 l_divided := round(cur_r.sal / cur_r.comm);
11 dbms_output.put_line(cur_r.ename ||': ' || l_divided);
12 end loop;
13 end;
14 /
ALLEN: 5
declare
*
ERROR at line 1:
ORA-01476: divisor is equal to zero
ORA-06512: at line 10
SQL>
See? Only the first one, Allen, had valid data. The rest of them weren't even calculated, as soon as the first error appeared.
But, if you rewrite it as I suggested, then all of them are processed:
SQL> declare
2 l_divided number;
3 begin
4 for cur_r in (select ename, sal, nvl(comm, 0) comm
5 from emp
6 where deptno = 30
7 order by ename
8 )
9 loop
10 begin
11 l_divided := round(cur_r.sal / cur_r.comm);
12 dbms_output.put_line(cur_r.ename ||': ' || l_divided);
13 exception
14 when zero_divide then
15 dbms_output.put_line(cur_r.ename ||': COMM is equal to zero');
16 end;
17 end loop;
18 end;
19 /
ALLEN: 5
BLAKE: COMM is equal to zero
JAMES: COMM is equal to zero
MARTIN: 1
TURNER: COMM is equal to zero
WARD: 3
PL/SQL procedure successfully completed.
SQL>
See if the above makes any sense in what you asked.
I have a PL/SQL script which used nested table. Below is the sample code.
type rec is record
(
--col data types here
)
type rec_table is table of rec;
v_rec_table rec_table := rec_table(); --initialising here.
arr_size integer := 0; --edit 1
...
...
begin
...
...
open cursor;
loop
fetch cursor bulk collect into v_rec_table limit arr_size; --edit
if nvl(v_rec_table.last,0) > 0 --it shows error is here.
then
...
...
end if;
The error is ORA-06531: Reference to uninitialized collection. Please help me debug this one.
If would help if you posted complete (sample) code (instead of "...").
Here's an example based on Scott's schema which works OK (your error line is line 14):
SQL> declare
2 type rec is record (id number);
3 type rec_table is table of rec;
4 v_rec_table rec_table := rec_table();
5
6 cursor c1 is select empno from emp;
7 begin
8 open c1;
9 loop
10 exit when c1%notfound;
11 fetch c1 bulk collect into v_rec_table;
12 end loop;
13 dbms_output.put_line('last = ' || v_rec_table.last);
14 if nvl(v_rec_table.last, 0) > 0 then
15 dbms_output.put_line('last exists');
16 end if;
17 close c1;
18 end;
19 /
last = 12
last exists
PL/SQL procedure successfully completed.
Though, I'm not sure what's that LOOP used for, as you could have done it as
SQL> declare
2 type rec is record (id number);
3 type rec_table is table of rec;
4 v_rec_table rec_table := rec_table();
5 begin
6 select empno bulk collect into v_rec_table from emp;
7 dbms_output.put_line('last = ' || v_rec_table.last);
8 end;
9 /
last = 12
PL/SQL procedure successfully completed.
Although your problem is not reproducible, there are few things I found could be improved in your code.
If you are using a bulk collect, the collection is initialised automatically and hence, this line is not required
v_rec_table rec_table := rec_table();
Also, as #Littlefoot mentioned, LOOP is not required unless you are using the LIMIT clause.
You may use the COUNT collection function instead of nvl(v_rec_table.last,0)
v_rec_table.count
Instead of defining a record type and bulk collecting into it, you may define a collection of cursor%ROWTYPE;
CURSOR cur is SELECT column1,column2 FROM tablename;
type rec_table is table of cur%ROWTYPE;
v_rec_table rec_table;
Apologies since i did not post whole code. The error occurred because i did not add index by to two columns in the record definition.
After reading through few articles i found my flaw.
I want to use DELETE Collection Method to delete some elements in collection
such as:
create or replace procedure testloop3 (clearaaa out nestedtable) as
type nestedtable is table of varchar2(255);
reply_ref_messageIds nestedtable;
getDelete_messageIds nestedtable;
begin
select distinct r.messagebox_id bulk collect into reply_ref_messageIds from reply r;
select m.id bulk collect into getDelete_messageIds from messagebox m;
getDelete_messageIds.delete(2);
getDelete_messageIds.delete(4);
getDelete_messageIds.delete(7);
getDelete_messageIds.delete(11);
getDelete_messageIds.delete(13);
for i in getDelete_messageIds.FIRST .. getDelete_messageIds.LAST loop
dbms_output.put_line(i);
end loop;
for i in 5 .. 12 loop
dbms_output.put_line(i);
end loop;
end;
and then I debug this procedure with plsql dev
-- Created on 2013/4/4 by THINKPAD
declare
-- Local variables here
aa nestedtable;
begin
-- Test statements here
testloop3(aa);
end;
and I get the indexes of getDelete_messageIds before remove which are 1 to 15.
However: when I debug to getDelete_messageIds.delete(2); it removes index 1 and 2...I can't explain why.
And then when I debug next statement getDelete_messageIds.delete(4); it removes index 3 and 4. And then getDelete_messageIds.delete(7); only removes index 7...
I can't understand...
your procedure, as posted, is showing nothing of the sort. you are simply looping around like
for idx in 1..15 loop
(.FIRST will resolve to 1 and .LAST will resolve to 15). it does not mean there are still 15 elements in the NT.
you are not checking to see if the indexes are deleted. I think you're confused about the proper way to loop through a nested table where there are gaps.
i.e. you can see the elements are deleted:
SQL> create table messagebox(id ) as select to_char(rownum) from dual connect by level <= 15;
Table created.
SQL> create or replace procedure testloop3
2 as
3 type nestedtable is table of varchar2(255);
4 getDelete_messageIds nestedtable;
5 v_idx number;
6 begin
7 select m.id bulk collect into getDelete_messageIds from messagebox m;
8 getDelete_messageIds.delete(2);
9 getDelete_messageIds.delete(4);
10 getDelete_messageIds.delete(7);
11 getDelete_messageIds.delete(11);
12 getDelete_messageIds.delete(13);
13 v_idx := getDelete_messageIds.first;
14 while v_idx is not null
15 loop
16 dbms_output.put_line(v_idx);
17 v_idx := getDelete_messageIds.next(v_idx);
18 end loop;
19 end;
20 /
Procedure created.
SQL> exec testloop3
1
3
5
6
8
9
10
12
14
15
so 2, 4, 7, 11, 13 are deleted. exactly as expected.
you can see
DECLARE
TYPE NumList IS TABLE OF NUMBER;
n NumList := NumList(1,3,5,7);
counter INTEGER;
BEGIN
DBMS_OUTPUT.PUT_LINE('N''s first subscript is ' || n.FIRST);
DBMS_OUTPUT.PUT_LINE('N''s last subscript is ' || n.LAST);
-- When the subscripts are consecutive starting at 1,
-- it's simple to loop through them.
FOR i IN n.FIRST .. n.LAST
LOOP
DBMS_OUTPUT.PUT_LINE('Element #' || i || ' = ' || n(i));
END LOOP;
n.DELETE(2); -- Delete second element.
-- When the subscripts have gaps
-- or the collection might be uninitialized,
-- the loop logic is more extensive.
-- Start at the first element
-- and look for the next element until there are no more.
IF n IS NOT NULL THEN
counter := n.FIRST;
WHILE counter IS NOT NULL
LOOP
DBMS_OUTPUT.PUT_LINE
('Element #' || counter || ' = ' || n(counter));
counter := n.NEXT(counter);
END LOOP;
ELSE
DBMS_OUTPUT.PUT_LINE('N is null, nothing to do.');
END IF;
END;
reference Finding the First or Last Collection Element