在mysql查询中通过父级获取所有子级

我有一个userid,managerid的表如下：

id       manager
-------  -------
admin    (NULL)       
james    admin  
user     james  
workad   user   
creator  workad 

现在我希望所有的孩子(后代)都有一个用户ID.换句话说,对于用户ID詹姆斯,我需要孩子用户,工作人员,创作者.因为詹姆斯是最高的父母(祖先).有任何查询在mysql中获取这样的结果…在此先感谢.

解决方法:

为此你需要有一个存储函数：

DELIMITER $$

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

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

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

    WHILE queue_length > 0 DO
        SET front_id = queue;
        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 Table1 WHERE manager = 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 $$

然后你可以这样打电话：

SELECT `id`, `manager`,GetFamilyTree(`id`) as children 
from Table1;

你也可以有过滤器：

SELECT `id`, `manager`,GetFamilyTree(`id`) as children 
from Table1 where `id` = 'james';

SAMPLE FIDDLE

标签：mysql,hierarchical-data
来源： https://codeday.me/bug/20191008/1872928.html