MySQL-邻接表模型-获取深度 [英] MySQL - Adjacency List Model - Get Depth

问题描述

我有一个组织表，该表具有一个id，一个parent_id和一个name列.该表中大约有5万行.只有一个顶级父级，其余都在此之下.在Oracle中，我可以使用level伪列轻松地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.我需要在一个查询中获取整棵树以及节点的深度.

关于StackOverflow的问题很多，但是似乎没有一个很好的答案，主要是链接到带有可疑解决方案的博客.当然可以通过某种简单的方式来做到这一点吗?

不幸的是，以任何方式修改表都不是一种选择，因此嵌套集是不可能的.

解决方案

这完全很有趣.我昨天刚从一个类似的问题上得到了+50的赏金:如何使用DBA StackExchange中的存储过程来实现此目的(2011年10月24日) >

我将发布相同的存储过程以及DBA StackExchange答案中的示例:

获取任何给定节点的父代的代码

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 ;

获取任意给定节点的密码的代码

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家族树(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 $$

为演示所有操作的执行情况，以下是示例数据

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;

这里是查看所有父母，祖先和家谱的查询

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

尝试一下！

I have an organization table that has an id, a parent_id, and a name column. There are roughly 50k rows in this table. There is just one top level parent and the rest are all under that. In Oracle, I am able to easily retrieve the current depth of a particular organization with the level pseudocolumn:

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

I am at a loss of what the proper way to do the above in MySQL is. I need to fetch the entire tree along with the node's depth in one query.

There are a plethora of questions on StackOverflow that have to do with this, but none of them seem to have a really good answer to it, mostly links to blogs with dubious solutions. Surely this is doable in some sort of straight-forward manner?

Unfortunately modifying the table in any way is not an option, so nested sets is not a possibility.

解决方案

This is totally hilarious. I just picked up a +50 bounty on a similar question literally yesterday : Using MySQL query to traverse rows to make a recursive tree

I referenced how to do this with Stored Procedures in the DBA StackExchange (October 24, 2011)

I will post the same stored procedures along with the examples from my DBA StackExchange answer:

Code to Get the Parent for Any Given Node

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 ;

Code to Get the Ancenstry for Any Given Node

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 ;

Code to Get the Family Tree (or Descendants) for Any Given Node

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 $$

To demonstrate the execution of everything, here is the sample data

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;

Here is the query to see all Parents, Ancestries, and Family Trees

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

Give it a Try !!!

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