mysql樹形結構遞歸查詢

https://www.cnblogs.com/chywx/p/9420726.html

之前一直用的是Oracle，對於樹形查詢可以使用start with ... connect by 

select * from menu start with id='130000' connect by id = prior parent_id;

 沒錯，這是Oracle所支持的

現在公司用的是mysql，對於這種查詢方式只能通過sql語句實現了

語言都是相通的，何況sql呢

mysql隨沒有自帶的語法支持，不過可以通過創建函數來實現遞歸查詢。

 

 如下圖所示。。。

 

直接上sql語句

create table `nodelist` (
    `id` int (11),
    `nodecontent` varchar (300),
    `pid` int (11)
); 
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('1','a',NULL);
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('2','b','1');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('3','c','1');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('4','d','2');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('5','e','3');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('6','f','3');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('7','g','5');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('8','h','7');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('9','i','8');
insert into `nodelist` (`id`, `nodecontent`, `pid`) values('10','j','8');

 

 之后創建一個函數

DROP FUNCTION IF EXISTS `getChild`$$
CREATE DEFINER=`root`@`localhost` FUNCTION `getChild`(rootId INT) RETURNS VARCHAR(1000) CHARSET utf8
BEGIN
        DECLARE ptemp VARCHAR(1000);
        DECLARE ctemp VARCHAR(1000);
               SET ptemp = '#';
               SET ctemp =CAST(rootId AS CHAR);
               WHILE ctemp IS NOT NULL DO
                 SET ptemp = CONCAT(ptemp,',',ctemp);
                SELECT GROUP_CONCAT(id) INTO ctemp FROM nodelist   
                WHERE FIND_IN_SET(pid,ctemp)>0; 
               END WHILE;  
               RETURN ptemp;  
    END$$
DELIMITER ;

OK，查詢可以通過將函數當做一個查詢條件。

SELECT * FROM nodelist WHERE FIND_IN_SET(id, getChild(3))

 

上面難度相對比較大，再補充一個簡單的自連接查詢

SELECT t1.id,t1.nodecontent,t2.nodecontent parentnodecontent FROM nodelist t1
LEFT JOIN nodelist t2
ON t1.pid = t2.id

可以了。

借鑒 https://www.jianshu.com/p/f99665266bb1

里面用到的內置函數 https://baijiahao.baidu.com/s?id=1595349117525189591&wfr=spider&for=pc

你只要能想到的，都有對應的解決方式，幸運的是你該踩得一些坑別人實現給你填好了。

 

BEGIN
DECLARE sTemp VARCHAR(4000);
DECLARE sTempChd VARCHAR(4000);

SET sTemp = '';
SET sTempChd = cast(cateId as char);

WHILE sTempChd is not NULL DO
if sTemp!='' then
SET sTemp = CONCAT(sTemp,',',sTempChd);
else
SET sTemp = CONCAT('',sTempChd);
end if;

SELECT group_concat(category.id) INTO sTempChd FROM product_front_category AS category where FIND_IN_SET(category.parent_id , sTempChd)>0;
END WHILE;
return sTemp;
END