MySQL – 邻接列表模型 – 获取深度

我有一个组织表,其中包含id,parent_id和name列.此表中大约有5万行.只有一个顶级父母,其余都在此之下.在Oracle中,我能够使用级别伪列轻松检索特定组织的当前深度：

SELECT id, parent_id, level, name
FROM organizations
START WITH parent_id = 1
CONNECT BY PRIOR id = parent_id

我不知道在MySQL中执行上述操作的正确方法是什么.我需要在一个查询中获取整个树以及节点的深度.

有关StackOverflow的大量问题与此有关,但它们似乎都没有真正好的答案,主要是链接到可疑解决方案的博客.当然这可以通过某种直接的方式实现吗？

不幸的是,以任何方式修改表都不是一种选择,因此不可能使用嵌套集.

解决方法:

这完全是搞笑的.我昨天在类似的问题上获得了50美元的奖金：Using MySQL query to traverse rows to make a recursive tree

我引用了how to do this with Stored Procedures in the DBA StackExchange(2011年10月24日)

我将发布相同的存储过程以及我的DBA StackExchange答案中的示例：

获取任何给定节点的父代码

DELIMITER $$
DROP FUNCTION IF EXISTS `junk`.`GetParentIDByID` $$
CREATE FUNCTION `junk`.`GetParentIDByID` (GivenID INT) RETURNS INT
DETERMINISTIC
BEGIN
    DECLARE rv INT;

    SELECT IFNULL(parent_id,-1) INTO rv FROM
    (SELECT parent_id FROM pctable WHERE id = GivenID) A;
    RETURN rv;
END $$
DELIMITER ;

获取任何给定节点的Ancenstry的代码

DELIMITER $$
DROP FUNCTION IF EXISTS `junk`.`GetAncestry` $$
CREATE FUNCTION `junk`.`GetAncestry` (GivenID INT) RETURNS VARCHAR(1024)
DETERMINISTIC
BEGIN
    DECLARE rv VARCHAR(1024);
    DECLARE cm CHAR(1);
    DECLARE ch INT;

    SET rv = '';
    SET cm = '';
    SET ch = GivenID;
    WHILE ch > 0 DO
        SELECT IFNULL(parent_id,-1) INTO ch FROM
        (SELECT parent_id FROM pctable WHERE id = ch) A;
        IF ch > 0 THEN
            SET rv = CONCAT(rv,cm,ch);
            SET cm = ',';
        END IF;
    END WHILE;
    RETURN rv;
END $$
DELIMITER ;

获取任何给定节点的族树(或后代)的代码

DELIMITER $$

DROP FUNCTION IF EXISTS `junk`.`GetFamilyTree` $$
CREATE FUNCTION `junk`.`GetFamilyTree` (GivenID INT) RETURNS varchar(1024) CHARSET latin1
DETERMINISTIC
BEGIN

    DECLARE rv,q,queue,queue_children VARCHAR(1024);
    DECLARE queue_length,front_id,pos INT;

    SET rv = '';
    SET queue = GivenID;
    SET queue_length = 1;

    WHILE queue_length > 0 DO
        SET front_id = FORMAT(queue,0);
        IF queue_length = 1 THEN
            SET queue = '';
        ELSE
            SET pos = LOCATE(',',queue) + 1;
            SET q = SUBSTR(queue,pos);
            SET queue = q;
        END IF;
        SET queue_length = queue_length - 1;

        SELECT IFNULL(qc,'') INTO queue_children
        FROM (SELECT GROUP_CONCAT(id) qc
        FROM pctable WHERE parent_id = front_id) A;

        IF LENGTH(queue_children) = 0 THEN
            IF LENGTH(queue) = 0 THEN
                SET queue_length = 0;
            END IF;
        ELSE
            IF LENGTH(rv) = 0 THEN
                SET rv = queue_children;
            ELSE
                SET rv = CONCAT(rv,',',queue_children);
            END IF;
            IF LENGTH(queue) = 0 THEN
                SET queue = queue_children;
            ELSE
                SET queue = CONCAT(queue,',',queue_children);
            END IF;
            SET queue_length = LENGTH(queue) - LENGTH(REPLACE(queue,',','')) + 1;
        END IF;
    END WHILE;

    RETURN rv;

END $$

为了演示所有内容的执行,这里是示例数据

USE junk
DROP TABLE IF EXISTS pctable;
CREATE TABLE pctable
(
    id INT NOT NULL AUTO_INCREMENT,
    parent_id INT,
    PRIMARY KEY (id)
) ENGINE=MyISAM;
INSERT INTO pctable (parent_id) VALUES (0);
INSERT INTO pctable (parent_id) SELECT parent_id+1 FROM pctable;
INSERT INTO pctable (parent_id) SELECT parent_id+2 FROM pctable;
INSERT INTO pctable (parent_id) SELECT parent_id+3 FROM pctable;
INSERT INTO pctable (parent_id) SELECT parent_id+4 FROM pctable;
INSERT INTO pctable (parent_id) SELECT parent_id+5 FROM pctable;
SELECT * FROM pctable;

这是查看所有父母,祖先和家谱的查询

SELECT
    id,parent_id,
    GetParentIDByID(id),
    GetAncestry(id),
    GetFamilyTree(id)
FROM pctable;

试试看 ！！！

标签：mysql,adjacency-list
来源： https://codeday.me/bug/20190530/1182894.html