Function returning REF CURSOR [duplicate] - oracle

This question already has answers here:
fetch from function returning a ref cursor to record
(3 answers)
Closed 7 years ago.
I have package like this:
CREATE OR REPLACE PACKAGE product_package AS
TYPE t_ref_cursor to IS REF CURSOR;
FUNCTION get_products_ref_cursor RETURN t_ref_cursor;
END product_package;
CREATE OR REPLACE PACKAGE BODY product_package AS
FUNCTION get_products_ref_cursor is RETURN t_ref_cursor IS
products_ref_cursor t_ref_cursor;
BEGIN
OPEN products_ref_cursor FOR
SELECT product_id, name, price FROM Products;
RETURN products_ref_cursor;
END get_products_ref_cursor;
END product_package;
My question is, how can I use function get_products_ref_cursor (ref cursor) to get list of products?

declare
type rec is record(produc_id number, name varchar2(x), price number);
type l_rec is table of rec;
v_l_rec l_rec;
v_cursor product_package.t_ref_cursor;
begin
v_cursor := product_package.get_products_ref_cursor;
fetch v_cursor bulk collect into v_l_rec;
-- in v_l_rec is list collection of products.
close v_cursor;
end;
Code wasn't tested.

It depends on the language or tool from which you are calling the function. If you are calling from SQL*Plus, you can just
print <variable_name>
where is the name of the PL/SQL bind variable to which you returned the function's results.
If you are in PL/SQL, you need to write a loop where you fetch... exit when %NOTFOUND... etc. There are a million examples, including the PL/SQL Users Guide.
If you are in Java, you cast the cursor object as a ResultSet and fetch its results in a loop.
Other languages will have other ways, but they mostly all entail looping through the cursor and fetching the results.
So... it depends on the caller's language.

Related

Pass Multivalue in WHERE IN ORACLE [duplicate]

This question already has answers here:
PL/SQL - comma separated list within IN CLAUSE
(4 answers)
Closed 4 years ago.
I need you help to pass a multivalue to a stored procedure in Oracle,
The values are created dynamically.
Basically I'm sending the values from .NET in a simple "string" and Oracle receives it as varchar2:
Stored Procedure
create or replace procedure sp_text_in
(text varchar2)
AS
CURSOR texts
IS
SELECT text FROM t_text where key_text in (text)
;
BEGIN
FOR reg IN texts LOOP
dbms_output.put_line(reg.text);
END LOOP;
end sp_text_in;
Example: the values can be:
select * from t_text where key_text in (197,198,196);
OR simply one value
select * from t_text where key_text in (197);
Ideal option is as per the link shared by #anonyXmous. Another sub optimal option is using dynamic SQL. But this could allow SQL injection. Dynamic SQL solution below.
create or replace procedure SP_TEXT_IN (TEXT varchar2)
as
type TEXTSTABTYP is table of varchar2(1000);
TEXTSTAB TEXTSTABTYP := TEXTSTABTYP();
begin
execute immediate 'select TEXT from T_TEXT where KEY_TEXT in ('||TEXT||')'
bulk collect into TEXTSTAB;
for IDX in TEXTSTAB.first..TEXTSTAB.last
loop
dbms_output.put_line(TEXTSTAB(IDX));
end loop;
end sp_text_in;

How to transfer cursor to the procedure dynamically and to set rowtype variable dynamically?

I have written the procedure with dynamically set cursor and %rowtype variable:
create or replace procedure process(source_table IN varchar2, my_cursor IN sys_refcursor)
is
c sys_refCURSOR;
rec my_cursor%rowtype;
begin
Dbms_Output.put_line('process starts');
open c for 'select * from '||source_table;
loop
fetch c into rec;
exit when c%notfound;
end loop;
close c;
Dbms_Output.put_line('process is over');
end process;
I am going to transfer cursor to the procedure with the function as follows:
CREATE OR REPLACE FUNCTION ddp_get_allitems (source_table IN Varchar2)
RETURN SYS_REFCURSOR
AS
my_cursor SYS_REFCURSOR;
BEGIN
OPEN my_cursor FOR 'SELECT * FROM '|| source_table;
RETURN my_cursor;
END ddp_get_allitems;
While compiling the procedure "process" I have the error:
PLS-00320 the declaration of the type of the expression is incomplete or malformed.
The compiler has hilighted the row with "rec my_cursor%rowtype;" as the error source. The varibale "source_table" and "my_cursor" are based upon the same table (select * from my_table).
So Why the error has arisen and how to remove it?
Since PL/SQL is statically typed the compiler needs to know the types of all the variables at compile time.
So there is no room for advanced metaprogramming. I'm afraid you can't do that.
There are, however, generic types found at SYS.STANDARD and a few internal functions accepting them.
-- The following data types are generics, used specially within package
-- STANDARD and some other Oracle packages. They are protected against
-- other use; sorry. True generic types are not yet part of the language.
type "<ADT_1>" as object (dummy char(1));
type "<RECORD_1>" is record (dummy char(1));
type "<TUPLE_1>" as object (dummy char(1));
type "<VARRAY_1>" is varray (1) of char(1);
type "<V2_TABLE_1>" is table of char(1) index by binary_integer;
type "<TABLE_1>" is table of char(1);
type "<COLLECTION_1>" is table of char(1);
type "<REF_CURSOR_1>" is ref cursor;
Take "<ADT_1>" for example. There is XMLTYPE constructor or DBMS_AQ ENQUEUE and DEQUEUE functions. You can pass any kind of object there.
For now you cannot use this datatype in custom functions since they are "not yet part of the language", but maybe some day there will be some support for this.
Just a thought to modify soe params which can basically same output
you want to achieve. Basically here for Function i have replaced
RETURN type as TABLE TYPE which can be easilt called in Procedure abd
rest manipulations can be done.Let me know if this helps
--SQL Object creation
CREATE TYPE source_table_obj IS OBJECT
(<TABLE_ATTRIBITES DECLARATION>);
--SQL TABLE type creation
CREATE TYPE source_table_tab IS TABLE OF source_table_obj;
--Function creation with nested table type as RETURN type
CREATE OR REPLACE FUNCTION ddp_get_allitems(
source_table IN VARCHAR2)
RETURN source_table_tab
AS
src_tab source_table_tab;
BEGIN
SELECT * BULK COLLECT INTO src_tab FROM source_table;
RETURN src_tab;
END ddp_get_allitems;
-- Using Function's OUT param as an IN Param for Procedure an do all the requird processing
CREATE OR REPLACE PROCEDURE process(
source_table IN VARCHAR2,
src_tab_in IN source_table_tab)
IS
BEGIN
FOR i IN src_tab_in.FIRST..src_tab_in.LAST
LOOP
dbms_output.put_line('job processing');
END LOOP;
END process;

Tail call for pipelined functions

I have some pipelined function:
create type my_tab_type as table of ...
create function my_func (X in number) return my_tab_type pipelined as
begin
loop
...
pipe row (...);
end loop;
return;
end;
Now I want to create another pipelined function my_func_zero which does the same as my_func but for fixed value of parameter: my_func_zero must be equivalent to my_func(0).
Can I implement my_func_zero without senseless and boring loop for processing every row returned by select * from table(my_func(0))?
P.S. That thread is a bit similar, but it does not contain answer to my question.
It's possible, but only if you don't declare your second function as pipelined because all functions of this type return results on row-by-row basis.
If you omit this requirement you can reach your target with bulk collect if you need typed cursor:
create function my_zero_func return my_tab_type
as
res_table my_tab_type;
begin
select my_type(field1, field2)
bulk collect into res_table
from table(my_func(0));
return res_table;
end;
Alternatively you can use untyped cursor:
create function my_ref_zero_func return sys_refcursor
as
vRes sys_refcursor;
begin
open vRes for select * from table(my_func(0));
return vRes;
end;
SQLFiddle
In a client application my_ref_zero_func results may be used without changes, but in the SQLFiddle it converted to XML representation because there are no way to demonstrate ref cursor with this tool.

PLSQL functions in packages query

I am having a table named employees..i want to write two functions.1st function by using refcursor it want to fetch all the rows from employess table...and the result wil be shown through 2nd function.These two functions should be in one single package
Your question shows very little industry or effort to work out a solution.
Start by reading the Oracle documentation and it'll help you immensely.
As an example of what you want to achieve:
CREATE OR REPLACE
PACKAGE ref_cur_package
AS
FUNCTION get_emp
RETURN SYS_REFCURSOR;
PROCEDURE show_emp;
END ref_cur_package;
CREATE OR REPLACE
PACKAGE BODY ref_cur_package
AS
FUNCTION get_emp
RETURN SYS_REFCURSOR
IS
emp_rc SYS_REFCURSOR;
BEGIN
OPEN emp_rc
FOR SELECT *
FROM emp;
RETURN emp_rc;
END get_emp;
PROCEDURE show_emp
IS
emp_rc SYS_REFCURSOR;
emp_row emp%ROWTYPE;
BEGIN
emp_rc := get_emp;
LOOP
FETCH emp_rc INTO emp_row;
EXIT WHEN emp_rc%NOTFOUND;
DBMS_OUTPUT.put_line('Employee: '||emp_row.firstname||' '||emp_row.lastname);
END LOOP;
CLOSE emp_rc;
END show_emp;
END ref_cur_package;
/
To see the output you'll need to set the serveroutput on.
You should also add an exception handler to force the closure of the ref cursor if there is a problem but I will leave that to you to research.

Cursor design and refactoring question

I have many cursors that all return rows with the same fields: a numeric ID field and an XMLType field. Every time I access one of these cursors (each cursor has now got its own function for access), I go through the same pattern:
--query behind cursor is designed to no more than one row.
for rec in c_someCursor(in_searchKey => local_search_key_value) loop
v_id := rec.ID
v_someXMLVar := rec.XMLDataField
end loop;
if v_someXMLVar is null then
/* A bunch of mostly-standard error handling and logging goes here */
end if;
exception
/* all cursor access functions have the same error-handling */
end;
As the pattern became more obvious, it made sense to centralize it in a single function:
function fn_standardCursorAccess(in_cursor in t_xmlCursorType, in_alt in XMLType) return XMLType is
v_XMLData XMLType;
begin
dbms_application_info.set_module(module_name => $$PLSQL_UNIT, action_name => 'fn_standardCursorAccess');
loop
fetch in_cursor
into v_XMLData;
exit when in_cursor%notfound;
end loop;
/*some additional standard processing goes here*/
return v_XML;
exception
/*standard exception handling happens here*/
end;
The problem I've run into is in calling this function. I now have to call it like this:
open v_curs for select /*blah blah blah*/ where key_field = x and /*...*/;
v_data := fn_standardCursorAccess(v_curs,alt);
close v_curs;
What I'd like to do is call it like this:
open v_curs for c_getSomeData(x);
v_data := fn_standardCursorAccess(v_curs,alt);
close v_curs;
...reason being to minimize the amount of changes to my code (I don't want to have to cut/paste all these cursors to the functions that depend on them, and in the case where multiple functions depend on the same cursor, I'll have to wrap that in a new function).
Unfortunately, this does not work, Oracle returns an error saying
Error: PLS-00222: no function with name 'C_GETSOMEDATA' exists in this scope
Is what I'm trying to do even possible?
(Oracle version is 10.2)
EDIT:
I think a better way to describe what I'm doing is pass a reference to an explicit cursor to a function that will perform some common routines on the data returned by the cursor.
It appears that I cannot use an open-for statement with an explcit cursor, is there any other way to get a reference to an explicit cursor so I can pass that reference to a function? Maybe there is some other way I could approach this problem?
EDIT:
Copying and pasting from my earlier reply to R Van Rijn's reply:
I tried declaring the cursor in the package specification, and referencing it with the package name: open v_curs for PKG.c_getSomeData(x);... This gives me a new error, saying that PKG.c_getSomeData must be a function or array to be used that way.
UPDATE:
I spoke to our DBA here, he says it is not possible to have a ref cursor point to an explicit cursor. It looks like I can't do this after all. Bummer. :(
concerning the Error PLS-00222:
An identifier being referenced as a function 'c_getSomeData' was not declared or actually represents another object (for example, it might have been declared as a procedure).
Check the spelling and declaration of the identifier. Also confirm that the declaration is placed correctly in the block structure
This means you must create a function that actually returns some value(s).
Does this test script and output represent what you are trying to do? Instead of open v_curs for c_getSomeData(x); I'm setting the cursor variable = to the output from the function.
Our Test Data:
set serveroutput on
--create demo table
drop table company;
create table company
(
id number not null,
name varchar2(40)
);
insert into company (id, name) values (1, 'Test 1 Company');
insert into company (id, name) values (2, 'Test 2 Company');
insert into company (id, name) values (3, 'Test 3 Company');
commit;
Create Packages
create or replace package test_pkg as
type cursor_type is ref cursor;
function c_getSomeData(v_companyID number) return cursor_type;
end test_pkg;
/
create or replace package body test_pkg as
function c_getSomeData(v_companyID number) return cursor_type
is
v_cursor cursor_type;
begin
open v_cursor for
select id,
name
from company
where id = v_companyID;
return v_cursor;
end c_getSomeData;
end test_pkg;
/
Run Our Procedure
declare
c test_pkg.cursor_type;
v_id company.id%type;
v_name company.name%type;
begin
c := test_pkg.c_getSomeData(1);
loop
fetch c
into v_id, v_name;
exit when c%notfound;
dbms_output.put_line(v_id || ' | ' || v_name);
end loop;
close c;
end;
/
1 | Test 1 Company
PL/SQL procedure successfully completed.
I confess to finding your requirements a trifle hard to divine. You have posted a lot of code, but as I suggested in my comment, not the parts which would illuminate the problem. So possibly the following is way off-beam. But it is an interesting issue.
The following code shows how we can define a common, geneneric REF CURSOR, populate it with specific data from different queries, and then process them in a standardised fashion. Again, I apologise if this does not fit your business logic; if such is the case, please edit your question to explain where I have made a bloomer..
Here is the generic ref cursor. ...
create or replace package type_def is
type xml_rec is record (id number, payload xmltype);
type xml_cur is ref cursor return xml_rec;
end type_def;
/
and here is the standatd processor
create or replace procedure print_xml_cur
( p_cur in type_def.xml_cur )
is
lrec type_def.xml_rec;
begin
loop
fetch p_cur into lrec;
exit when p_cur%notfound;
dbms_output.put_line('ID='||lrec.id);
dbms_output.put_line('xml='||lrec.payload.getClobVal());
end loop;
close p_cur;
end print_xml_cur;
/
Two procedures which return the standard cursor with different data....
create or replace function get_emp_xml
( p_id in emp.deptno%type )
return type_def.xml_cur
is
return_value type_def.xml_cur;
begin
open return_value for
select deptno
, sys_xmlagg(sys_xmlgen(ename))
from emp
where deptno = p_id
group by deptno;
return return_value;
end get_emp_xml;
/
create or replace function get_dept_xml
( p_id in dept.deptno%type )
return type_def.xml_cur
is
return_value type_def.xml_cur;
begin
open return_value for
select deptno
, sys_xmlagg(sys_xmlgen(dname))
from dept
where deptno = p_id
group by deptno;
return return_value;
end get_dept_xml;
/
Now let's put it all together ....
SQL> set serveroutput on size unlimited
SQL>
SQL> exec print_xml_cur(get_emp_xml(40))
ID=40
xml=<?xml
version="1.0"?>
<ROWSET>
<ENAME>GADGET</ENAME>
<ENAME>KISHORE</ENAME>
</ROWSET>
PL/SQL procedure successfully completed.
SQL> exec print_xml_cur(get_dept_xml(20))
ID=20
xml=<?xml version="1.0"?>
<ROWSET>
<DNAME>RESEARCH</DNAME>
</ROWSET>
PL/SQL procedure successfully completed.
SQL>
OK, so the short answer from Oracle is: "can't be done!"
The short answer from me is: "Yeah - like Oracle is gonna stop me! So yes you can....but you need to be sneaky ... oh yes, and there is a 'but' or two....in fact...ugh!"
So, how can you pass your explicit cursor by reference? By nesting it into another cursor using the CURSOR() construct!
e.g.)
CREATE OR REPLACE package CFSDBA_APP.test_Cursor
as
function get_cursor(ed_id number) return sys_refcursor;
end;
/
CREATE OR REPLACE package body CFSDBA_APP.test_Cursor
as
function get_cursor(ed_id number) return sys_refcursor
is
test_Cur sys_refcursor;
cursor gettest is
select CURSOR( -pass our actual query back as a nested CURSOR type
select ELCTRL_EVNT_ELCTRL_DISTRCT_ID,
ELECTORAL_DISTRICT_ID,
ELECTORAL_EVENT_ID
from ELCTRL_EVNT_ELCTRL_DISTRCT
where electoral_District_id = ed_id)
from dual;
begin
open gettest;
fetch gettest into test_Cur;
return test_Cur;
end;
end;
/
So what is the problem with this solution? It has a leak! The outer gettest cursor is never closed, because we don't close it and the client will only close the reference to the nested cursor that was selected for them - not the main cursor. And we can't close it automatically because closign the parent would force closing the nested cursor that you have returned by reference - and it is entirely likely that the client has not done using it.
So we have to leave a cursor open in order to return the nested cursor.
And if the user tried calling get_Cursor again with a new value of ed_id, they would discover that the session persistence in the package meant that the cursor handle is still in use and an error would be raised.
Now, we could fix that by first checking and closing the explicit cursor:
if gettest%isopen then
close gettest;
end if;
open gettest;
fetch gettest into test_Cur;
return test_Cur;
But still - what if the user never calls this again? How long 'til Oracle garbage-collects the cursor? And how many users running how many sessions calling how many functions that use this construct will be leaving cursors open after they are done with them? Better count on a huuuuuge overhead to leave all those open cursors layin' about!
No, you would need to have the users do a callback to explicitely close it or you would be clogging the database. But doing this would require changing the scope of the explicit cursor so that both functions can access it: So we need to make it at package scope, not function scope
CREATE OR REPLACE package CFSDBA_APP.test_Cursor
as
function get_cursor(ed_id number) return sys_refcursor;
function close_cursor return sys_refcursor;
end;
/
CREATE OR REPLACE package body CFSDBA_APP.test_Cursor
as
cursor l_gettest(p_ed_id in number) is
select CURSOR(
select ELCTRL_EVNT_ELCTRL_DISTRCT_ID, ELECTORAL_DISTRICT_ID, ELECTORAL_EVENT_ID
from ELCTRL_EVNT_ELCTRL_DISTRCT
where electoral_District_id = p_ed_id)
from dual;
function get_cursor(ed_id number) return sys_refcursor
is
l_get_Cursor sys_refcursor;
begin
open l_gettest (ed_id);
fetch l_gettest into l_get_Cursor;
return l_get_cursor;
end;
function close_cursor return sys_refcursor
is
begin
if l_gettest%isopen then
close l_gettest;
end if;
return pkg_common.generic_success_cursor;
end;
end;
/
OK, plugged the leak. Except it cost us a network round trip instead of the hard parse,...oh wait - and also except embedding a bind variable into an explicit cursor declared at this level is probably going to cause scoping issues of its own which was the reason we wanted to do this in the first place!
Oh, and in a session-pooling environment can two users step on each other's cursors? IF they aren't very carefull about doing an open-fetch-close before returning the session to the pool - we could wind up with some really interesting (and impossible to debug) results!
And how much do you trust the maintainers of the client code to be extra-diligent on this? YEah - me too.
So the short answer is: Yes, with a bit of sneakiness it could be done despite Oracle saying it can't.
The better answer is: But please don't! The extra round trip and potential for memory leaks and client code errors causing data problems makes this a very scary proposition.
It appears that what I wanted to do (have an open-for statement reference an existing explicit cursor) is simply not allowed in Oracle. :(

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