显示基于层次结构的数据[Grand Parent - ＆gt;家长 - ＆gt;孩子]

Question

您好，我想将数据显示为层次结构，如下图所示

这是我的数据库表结构

这是我用过的查询但不是我想要的完美结果

SELECT 

t1.parent_id AS primary_Id,
t2.parent_id AS secondary_Id,
t3.parent_id AS teritiary_Id

FROM ucode AS t1
LEFT JOIN ucode AS t2 ON t2.parent_id = t1.id
LEFT JOIN ucode AS t3 ON t3.parent_id = t2.parent_id

，输出

这不是我需要的

还有一种我试过的方式

SELECT 

    t1.parent_id AS primary_Id,
    t2.parent_id AS secondary_Id,
    t3.parent_id AS teritiary_Id

    FROM ucode AS t1
    LEFT JOIN ucode AS t2 ON t2.parent_id = t1.id
    LEFT JOIN ucode AS t3 ON t3.parent_id = t2.id

，输出

你能为我提供适当的解决方案..

Answer 1

这是查询

Select gparent, parent, id from ucode as c_tbl,
(SELECT gparent, id as parent from ucode as p_tbl,
(SELECT id as gparent FROM `ucode` WHERE parent_id = 0) as gp_tbl
where p_tbl.parent_id = gp_tbl.gparent) parent_tbl
where c_tbl.parent_id = parent_tbl.parent;

点击Demo获取结果

Answer 2

您需要使用INNER JOIN代替LEFT JOIN并限制查询以仅返回有子女使用的父母WHERE

我的查询不会跳过您想要显示的列值，但您可以在循环查询结果时执行PHP。

SELECT 
    t1.parent_id AS primary_Id,
    t2.parent_id AS secondary_Id,
    t3.parent_id AS teritiary_Id
FROM ucode AS t1
INNER JOIN ucode AS t2 ON (t2.parent_id = t1.id )
INNER JOIN ucode AS t3 ON (t3.parent_id = t2.id )
where t1.parent_id = 0

<强> Demo