Convert "select top 5 ..." in Oracle8i

Question

-- We are in the process of migrating application from SQLserver7 to Oracle8i,
-- and trying to convert a procedure to return top 5
-- rows given a search string.
-- In SQLserver7, "select top 5 ... "
-- The Oracle8i Application Developer's Guide - Fundamentals
-- recommends to use rownum, the query runs OK in SQL*Plus,
-- but gets error when used in a procedure with returned cursor.
-- Is there any solution for it?
-- Following is the sample query and procedure (in a package)
-- Query returns top 5 rows
select t.rank, t.productid, t.productname
from (
Select score(0) as rank, productid, productname
from Product
where status = 'A'
and contains(productname, 'Frog', 0) > 0
order by rank desc, productid
) t
where rownum < 6;
-- Proc Name: Pr_Test
-- Purpose: Retrieve product data for a specified search string
CREATE OR REPLACE PACKAGE pkg_test
IS
TYPE RT1 IS RECORD (
Rank NUMBER(10),
ProductID Product.ProductID%TYPE,
ProductName Product.ProductName%TYPE
TYPE RCT1 IS REF CURSOR RETURN RT1;
PROCEDURE pr_test
(i_searchstring IN VARCHAR2 ,
io_prdcursor IN OUT RCT1);
END pkg_test;
CREATE OR REPLACE PACKAGE BODY pkg_test
AS
PROCEDURE pr_test
(i_searchstring IN VARCHAR2 ,
io_prdcursor IN OUT RCT1)
IS
BEGIN
OPEN io_prdcursor FOR
select t.rank, t.productid, t.productname
from (
Select score(0) as rank, productid, productname
from Product
where status = 'A'
and contains(productname, i_searchstring, 0) > 0
order by rank desc, productid
) t
where rownum < 6;
END pr_test;
END pkg_test;
-- Following is the error message when compiling the package body:
Warning: Package Body created with compilation errors.
SQL> show error
Errors for PACKAGE BODY PKG_TEST:
LINE/COL ERROR
19/7 PLS-00103: Encountered the symbol "ORDER" when expecting one of
the following:
) * & - + / mod rem with an exponent (**) and or group having
intersect minus start union where connect &#0124; &#0124;
The symbol ")" was substituted for "ORDER" to continue.
20/11 PLS-00103: Encountered the symbol ")" when expecting one of the
following:
. ( , * @ % & - + ; / for mod rem an exponent (**) asc desc
&#0124; &#0124;
-- Run the procedure and get the results
declare
i number := 0;
v_string varchar2(50) := 'CAT';
-- v_string varchar2(50) := 'FROG%';
v_RC1 pkg_test.RCT1;
v_Score NUMBER(10);
v_ProductID Product.ProductID%TYPE;
v_ProductName Product.ProductName%TYPE;
begin
pkg_test.pr_test (v_string, v_RC1);
LOOP
FETCH v_RC1 INTO v_Score,v_ProductID,v_ProductName;
EXIT WHEN (v_RC1%NOTFOUND);
DBMS_OUTPUT.put_line(substr('Score='&#0124; &#0124;v_score&#0124; &#0124;', ProdID='&#0124; &#0124;v_ProductID ,1,255));
i := i + 1;
END LOOP;
DBMS_OUTPUT.put_line('Total '&#0124; &#0124;i&#0124; &#0124;' records retrieved.');
end;
null

Answer 1

http://www.orafaq.org/faqsql.htm#TOP
This may be of use, the plsql cursor declaration syntax may not have all the facilities of runnning the query from sqlplus:
How does one select the TOP N rows from a table?
Form Oracle8i one can have an inner-query with an ORDER BY clause. Look at this example:
SELECT *
FROM (SELECT * FROM my_table ORDER BY col_name_1 DESC)
WHERE ROWNUM < 10;
Use this workaround with prior releases:
SELECT *
FROM my_table a
WHERE 10 >= (SELECT COUNT(DISTINCT maxcol)
FROM my_table b
WHERE b.maxcol >= a.maxcol)
ORDER BY maxcol DESC;
Turloch