PLSQL实现字符串排序

概述：

现在有一张表tt，表结构如下：

CREATE TABLE tt (NAME VARCHAR2(20));
INSERT INTO tt VALUES('abcd');
INSERT INTO tt VALUES('dabc');
INSERT INTO tt VALUES('ewqa');
COMMIT;

需求1：

实现在name字段值的各字符之间加一个逗号，如abcd变成a,b,c,d 
实现：

SELECT rtrim(REGEXP_REPLACE(NAME, '(.)', '\1,'),',') FROM tt;

需求2：

实现需求1的同时还要实现各字符的排序，如dabc变成a,b,c,d 
实现：

WITH t AS (SELECT ROWNUM ID,NAME FROM tt), --根据id解析字符串数组并排序 T_STR AS (SELECT ID, SUBSTR(NAME, LEVEL, 1) NEWSTR FROM T CONNECT BY LEVEL <= LENGTH(NAME) AND PRIOR ID = ID AND PRIOR DBMS_RANDOM.VALUE IS NOT NULL ORDER BY ID, NEWSTR) --根据id将数据拼接 SELECT ID, LISTAGG(NEWSTR, ',') WITHIN GROUP(ORDER BY ID, NEWSTR) FROM T_STR GROUP BY ID;

下面通过一函数来实现(11g)：

--创建测试表
CREATE TABLE tt (NAME VARCHAR2(20));
INSERT INTO tt VALUES('abcd');
INSERT INTO tt VALUES('dabc');
INSERT INTO tt VALUES('ewqa');
COMMIT;

--创建一函数 fn_sortstr
CREATE OR REPLACE FUNCTION fn_sortstr(str IN varchar2) RETURN VARCHAR2 AS l_return VARCHAR2(4000);
BEGIN WITH t AS (SELECT 1 ID,str FROM dual), --根据id解析字符串数组并排序 T_STR AS (SELECT ID, SUBSTR(str, LEVEL, 1) NEWSTR FROM t CONNECT BY LEVEL <= LENGTH(str) AND PRIOR ID = ID AND PRIOR DBMS_RANDOM.VALUE IS NOT NULL ORDER BY ID, NEWSTR) --根据id将数据拼接 SELECT LISTAGG(NEWSTR, ',') WITHIN GROUP(ORDER BY ID, NEWSTR) INTO l_return FROM T_STR GROUP BY ID;
RETURN l_return;
END;
--使用
SELECT fn_sortstr(NAME) FROM tt;

下面通过一函数来实现(10g)： 
–创建测试表

CREATE TABLE tt (NAME VARCHAR2(20));
INSERT INTO tt VALUES('abcd');
INSERT INTO tt VALUES('dabc');
INSERT INTO tt VALUES('ewqa');
COMMIT;
--创建一函数 fn_sortstr
CREATE OR REPLACE FUNCTION fn_sortstr(str IN varchar2) RETURN VARCHAR2 AS l_return VARCHAR2(4000);
BEGIN WITH t AS (SELECT 1 ID,str FROM dual), --根据id解析字符串数组并排序 T_STR AS (SELECT ID, SUBSTR(str, LEVEL, 1) NEWSTR FROM t CONNECT BY LEVEL <= LENGTH(str) AND PRIOR ID = ID AND PRIOR DBMS_RANDOM.VALUE IS NOT NULL ORDER BY ID, NEWSTR) --根据id将数据拼接 SELECT wmsys.wm_concat(NEWSTR) INTO l_return FROM T_STR GROUP BY ID;
RETURN l_return;
END;
--使用
SELECT fn_sortstr(NAME) FROM tt;