-- sort comma separated substrings with unoptimized bubble sort
DROP FUNCTION IF EXISTS sortString;
DELIMITER |
CREATE FUNCTION sortString(inString TEXT) RETURNS TEXT
BEGIN
DECLARE delim CHAR(1) DEFAULT ','; -- delimiter
DECLARE strings INT DEFAULT 0; -- number of substrings
DECLARE forward INT DEFAULT 1; -- index for traverse forward thru substrings
DECLARE backward INT; -- index for traverse backward thru substrings, position in calc. substrings
DECLARE remain TEXT; -- work area for calc. no of substrings
-- swap areas TEXT for string compare, INT for numeric compare
DECLARE swap1 TEXT; -- left substring to swap
DECLARE swap2 TEXT; -- right substring to swap
SET remain = inString;
SET backward = LOCATE(delim, remain);
WHILE backward != 0 DO
SET strings = strings + 1;
SET backward = LOCATE(delim, remain);
SET remain = SUBSTRING(remain, backward+1);
END WHILE;
IF strings < 2 THEN RETURN inString; END IF;
REPEAT
SET backward = strings;
REPEAT
SET swap1 = SUBSTRING_INDEX(SUBSTRING_INDEX(inString,delim,backward-1),delim,-1);
SET swap2 = SUBSTRING_INDEX(SUBSTRING_INDEX(inString,delim,backward),delim,-1);
IF swap1 > swap2 THEN
SET inString = TRIM(BOTH delim FROM CONCAT_WS(delim
,SUBSTRING_INDEX(inString,delim,backward-2)
,swap2,swap1
,SUBSTRING_INDEX(inString,delim,(backward-strings))));
END IF;
SET backward = backward - 1;
UNTIL backward < 2 END REPEAT;
SET forward = forward +1;
UNTIL forward + 1 > strings
END REPEAT;
RETURN inString;
END |
DELIMITER ;
要进行程序调用,必须使用,
-- example call:
SET @Xstr = "red,blue,green"; // for query purpose only you need to write within (SQL Query here for that row)
SELECT sortString(@Xstr) AS s1
create function f_comma_list_order ( t text )
returns text
begin
declare v_c int;
drop temporary table if exists tmp;
create temporary table tmp ( v text );
set v_c = 1;
while( v_c > 0 ) do
select locate(',', t) into v_c;
if (v_c>0) then
insert into tmp select substr(t, 1, v_c-1);
set t = substr(t, v_c+1);
else
insert into tmp values (t);
end if;
end while;
select group_concat(v order by v) into t
from tmp;
return t;
end
2条答案
按热度按时间yeotifhr1#
操作步骤,
1.首先,您需要调用一个过程来对值进行排序
2.那就叫你的程序
下面是创建mysql过程的代码
要进行程序调用,必须使用,
请参阅文档指南Map单击此处阅读
另外,如果你有兴趣学习的话,还有另外一种方法,那就是在\集中查找\请你从stackoverflow的一个问题中找到一些想法。单击此处阅读
fzwojiic2#
您可以创建一个函数,对列中的项进行排序:
然后调用函数: