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utilities/csort.sql

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-- ----------------------------------------------------------------------------------------------
--
-- Script: csort.sql
--
-- Utility: CSORT (Collection SORTer)
--
-- Author: Adrian Billington
-- www.oracle-developer.net
--
-- Description: A simple package containing two functions to sort collections:
--
-- 1) sort
-- 2) sort_small
--
-- These functions contain techniques suitable for the size of collection that
-- needs to be sorted. In most cases, the SORT function will be the most efficient
-- to use. The SORT_SMALL function should be the most efficient when dealing with
-- tiny collections of just a few small elements. For more information on sorting
-- collections and choosing the right function, read the following article:
--
-- http://www.oracle-developer.net/display.php?id=428
--
-- This package supports collections of a single nested table type of strings.
-- Nested table types are the most flexible of collections - they can be used
-- in all SQL and PL/SQL assignments and they are supported by all MULTISET
-- operations. To implement sorts for your own standard collection type, simply
-- replace the name of the type used throughout the utility.
--
-- This utility can be made generic (i.e. to support any nested table type) by
-- using either ANYDATA or subtitutable types, but this would be slower and more
-- complex to use.
--
-- Usage: a) Sort a pre-populated collection in SQL
-- -----------------------------------------
-- SELECT CSORT.SORT(collection)
-- FROM table_name;
--
-- b) Sort a pre-populated small collection in PL/SQL
-- --------------------------------------------------
-- PROCEDURE ... ( p_collection IN varchar2_ntt ) IS
-- v_sorted_collection varchar2_ntt := varchar2_ntt();
-- BEGIN
-- ...
-- v_sorted_collection := CSORT.SORT_SMALL(p_collection);
-- ...
-- END;
--
-- c) Sort a collection descending in SQL
-- --------------------------------------
-- SELECT CSORT.SORT(collection, 'Y')
-- FROM table_name;
--
-- d) Distinct sort a collection in SQL
-- ------------------------------------
-- SELECT CSORT.SORT(collection, 'N', 'Y')
-- FROM table_name;
--
-- ...or...
--
-- SELECT CSORT.SORT(collection, NULL, 'Y')
-- FROM table_name;
--
-- e) Distinct descending sort in SQL
-- ----------------------------------
-- SELECT CSORT.SORT(collection, 'Y', 'Y')
-- FROM table_name;
--
-- Versions: This utility will work for all versions of 9i Release 2 and upwards.
-- To make it 8i compatible, remove the SORT_SMALL function and use the
-- SORT function for all requirements.
--
-- Required: 1) CREATE PROCEDURE
-- 2) CREATE TYPE
-- 3) CREATE PUBLIC SYNONYM (see bottom of script and exclude as necessary)
--
-- Disclaimer: http://www.oracle-developer.net/disclaimer.php
--
-- ----------------------------------------------------------------------------------------------
CREATE TYPE varchar2_ntt AS TABLE OF VARCHAR2(4000);
/
CREATE PACKAGE csort AS
FUNCTION sort( p_collection IN varchar2_ntt,
p_descending IN VARCHAR2 DEFAULT 'N',
p_distinct IN VARCHAR2 DEFAULT 'N' )
RETURN varchar2_ntt;
FUNCTION sort_small( p_collection IN varchar2_ntt,
p_descending IN VARCHAR2 DEFAULT 'N',
p_distinct IN VARCHAR2 DEFAULT 'N' )
RETURN varchar2_ntt;
END csort;
/
CREATE PACKAGE BODY csort AS
FUNCTION boolean_option( p_option IN VARCHAR2 )
RETURN BOOLEAN IS
BEGIN
RETURN UPPER(p_option) = 'Y';
END boolean_option;
-----------------------------------------------------------------
FUNCTION sort(
p_collection IN varchar2_ntt,
p_descending IN VARCHAR2 DEFAULT 'N',
p_distinct IN VARCHAR2 DEFAULT 'N' ) RETURN varchar2_ntt IS
v_collection varchar2_ntt := varchar2_ntt();
BEGIN
EXECUTE IMMEDIATE
'SELECT ' || CASE
WHEN boolean_option(p_distinct)
THEN 'DISTINCT'
END || ' column_value
FROM TABLE(:p_collection)
ORDER BY column_value ' || CASE
WHEN boolean_option(p_descending)
THEN 'DESC'
ELSE 'ASC'
END
BULK COLLECT INTO v_collection
USING p_collection;
RETURN v_collection;
END sort;
-----------------------------------------------------------------
FUNCTION sort_small( p_collection IN varchar2_ntt,
p_descending IN VARCHAR2 DEFAULT 'N',
p_distinct IN VARCHAR2 DEFAULT 'N' )
RETURN varchar2_ntt IS
TYPE sorter_aat IS TABLE OF PLS_INTEGER
INDEX BY VARCHAR2(4000);
v_collection varchar2_ntt := varchar2_ntt();
v_sorter sorter_aat;
v_sorter_idx VARCHAR2(4000);
v_source_idx PLS_INTEGER;
v_descending BOOLEAN := boolean_option(p_descending);
v_distinct BOOLEAN := boolean_option(p_distinct);
BEGIN
-- Sort the collection using the sorter array...
-- --------------------------------------------------
v_source_idx := p_collection.FIRST;
WHILE v_source_idx IS NOT NULL LOOP
v_sorter_idx := p_collection(v_source_idx);
v_sorter(v_sorter_idx) := CASE
WHEN NOT v_sorter.EXISTS(v_sorter_idx)
OR v_distinct
THEN 1
ELSE v_sorter(v_sorter_idx) + 1
END;
v_source_idx := p_collection.NEXT(v_source_idx);
END LOOP;
-- Assign sorted elements back to collection...
-- --------------------------------------------------
v_sorter_idx := CASE
WHEN v_descending
THEN v_sorter.LAST
ELSE v_sorter.FIRST
END;
WHILE v_sorter_idx IS NOT NULL LOOP
-- Handle multiple copies of same value. For distinct
-- collections, there will only be one element...
-- --------------------------------------------------
FOR i IN 1 .. v_sorter(v_sorter_idx) LOOP
v_collection.EXTEND;
v_collection(v_collection.LAST) := v_sorter_idx;
END LOOP;
v_sorter_idx := CASE
WHEN v_descending
THEN v_sorter.PRIOR(v_sorter_idx)
ELSE v_sorter.NEXT(v_sorter_idx)
END;
END LOOP;
RETURN v_collection;
END sort_small;
END csort;
/
CREATE PUBLIC SYNONYM varchar2_ntt FOR varchar2_ntt;
CREATE PUBLIC SYNONYM csort FOR csort;
GRANT EXECUTE ON varchar2_ntt TO PUBLIC;
GRANT EXECUTE ON csort TO PUBLIC;