请教一个 mysql 递归获取父级字段+子级字段的问题

基本环境是 mysql 5.7 ，不支持 CTE 语法。

表结构如下：

-- auto-generated definition
create table t_restree
(
c_resid varchar(255) collate gbk_bin not null
primary key,
c_resname varchar(255) collate gbk_bin null,
c_resalias varchar(255) collate gbk_bin null,
c_pid varchar(255) collate gbk_bin null,
c_restype varchar(255) collate gbk_bin null,
c_order int null,
c_perm longtext null,
c_resdesc varchar(255) collate gbk_bin null,
c_created datetime null,
c_lastmodified datetime null,
c_status varchar(255) collate gbk_bin null,
c_extended longtext null
);

create index c_restree_pid
on t_restree (c_pid);

create index c_restree_restype
on t_restree (c_restype);

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子级里面 c_pid 就是父级的 c_resid 最后一级的 c_pid 是个空值
需要获取
父级 c_resname/子级 c_resname 直到 c_pid 是空值。应该是需要递归获取
目前是建立一个临时表，加了两个字段，写了一个存储过程，但是存储过程目前执行不完。
CREATE TABLE new_table AS
SELECT *
FROM t_restree
WHERE 1 = 0;
INSERT INTO new_table
SELECT *
FROM t_restree;

ALTER TABLE new_table
ADD COLUMN c_resname_full VARCHAR(255) COLLATE gbk_bin NULL,
ADD COLUMN c_resalias_full VARCHAR(255) COLLATE gbk_bin NULL;

DELIMITER //

CREATE PROCEDURE update_recursive()
BEGIN
DECLARE c_resid_var VARCHAR(1024);
DECLARE c_resname_var VARCHAR(1024);
DECLARE c_resalias_var VARCHAR(1024);

update new_table SET c_resname_full = null, c_resalias_full = null WHERE 1=1;
-- 初始化根节点
UPDATE new_table SET c_resname_full = c_resname, c_resalias_full = c_resalias WHERE c_pid IS NULL;

-- 递归更新子节点
REPEAT
SET c_resid_var = NULL;
SET c_resname_var = NULL;
SET c_resalias_var = NULL;

-- 获取未更新的子节点
SELECT c_resid, c_resname, c_resname_full
INTO c_resid_var, c_resname_var, c_resalias_var
FROM new_table
WHERE c_resname_full IS NULL
LIMIT 1;

-- 更新子节点的
UPDATE new_table t1
JOIN new_table t2 ON t1.c_pid = t2.c_resid
SET t1.c_resname_full = CONCAT(t2.c_resname_full, '/', t1.c_resname)
WHERE t1.c_resid = c_resid_var;

UNTIL c_resid_var IS NULL END REPEAT;
END //

DELIMITER ;

call update_recursive();
困惑好久了，来次请教一下。

cnzmz

2023-08-31 10:58:39 +08:00

DROP PROCEDURE IF EXISTS getResAlisa;
DELIMITER $$
CREATE PROCEDURE getResAlisa(IN resid varchar(255), OUT path TEXT)
BEGIN
DECLARE catname VARCHAR(255);
DECLARE temppath TEXT;
DECLARE tempparent VARCHAR(255);
SET max_sp_recursion_depth = 255;
SELECT c_resalias, c_pid FROM t_restree WHERE c_resid=resid INTO catname, tempparent;
IF tempparent IS NULL
THEN
SET path = catname;
ELSE
CALL getResAlisa(tempparent, temppath);
SET path = CONCAT(temppath, '/', catname);
END IF;
END$$
DELIMITER ;

DROP FUNCTION IF EXISTS getResAlisa;
DELIMITER $$
CREATE FUNCTION getResAlisa(cat_id VARCHAR(255)) RETURNS TEXT DETERMINISTIC
BEGIN
DECLARE res TEXT;
CALL getResAlisa(cat_id, res);
RETURN res;
END$$
DELIMITER ;

弄好了，写了一个存储过程，写了一个函数，终于查出来了，参考的是 https://stackoverflow.com/questions/20215744/how-to-create-a-mysql-hierarchical-recursive-query