MySql修改preorder树来创建url [英] MySql Modified preorder tree to create url

问题描述

这个问题是基于我之前对

我试图编写一个mysql查询，将使用产生以下输出的类别表为页面表中的所有行生成URL。

预期行：

  / content / article / array / oops / classes 
 / content / article / array / oops / objects 
 / content / article / php / index 
 / content / article / php / quiz 
 / content / article / php / strings / strstr 
 / content / article / php / strings / str_substr 
 / content / blog / something1 
 / content / blog / something2 
 / content / blog / java / test-java 
 / content / blog / java / final-method 
 / content / about-us 
 / content / contact-us 
  

我尝试了类别表，参考管理层次MySQL中的数据。以下SQL查询在类别表中检索标题oops的单个路径。

  SELECT concat（'/'，group_concat（parent.title separator'/'））as url 
 FROM category AS节点，类别AS父
 WHERE node.lft BETWEEN parent.lft和parent.rgt 
 AND node.title ='oops'
 ORDER BY parent.lft; 
  

解决方案

这样的东西就够了...

  SELECT CONCAT_WS（'/'，x.path，y.page_name）full_path 
 FROM 
 id，GROUP_CONCAT（parent.title ORDER BY parent.lft SEPARATOR'/'）path 
 FROM类别节点
 JOIN类别parent 
 ON node.lft BETWEEN parent.lft和parent.rgt 
 GROUP 
 BY node.title 
 ORDER 
 BY node.lft 
）x 
 JOIN页面y 
 ON y.category_id = x.id; 
  

This question is based on my previous question on stackoverflow. This time I am trying to generate urls for all the rows in pages table using the Modified Preorder Tree method.

Here are the MySql Tables: [Note: I have added the 'parent' column just for the viewers to understand the parent-child relationship in the category table. The actual Modified Preorder Tree method does not use parent column (parent-child relationship)]

Category table:

Pages table

I am trying to write a mysql query that will generate URLs for all the rows in the pages table using the category table producing the below output.

Expected rows:

/content/article/array/oops/classes
/content/article/array/oops/objects
/content/article/php/index
/content/article/php/quiz
/content/article/php/strings/strstr
/content/article/php/strings/str_substr
/content/blog/something1
/content/blog/something2
/content/blog/java/test-java
/content/blog/java/final-method
/content/about-us
/content/contact-us

Here is what I tried on category table referring to Managing Hierarchical Data in MySQL. The below SQL query retrieve single path for title 'oops' in category table.

SELECT concat('/',group_concat(parent.title separator '/')) as url
FROM category AS node, category AS parent
WHERE node.lft BETWEEN parent.lft AND parent.rgt
AND node.title = 'oops'
ORDER BY parent.lft;

解决方案

Something like this should suffice...

SELECT CONCAT_WS('/',x.path,y.page_name) full_path
  FROM
     ( SELECT node.id, GROUP_CONCAT(parent.title ORDER BY parent.lft SEPARATOR '/') path
         FROM category node
         JOIN category parent
           ON node.lft BETWEEN parent.lft AND parent.rgt
        GROUP 
           BY node.title
        ORDER 
           BY node.lft
     ) x
  JOIN pages y
    ON y.category_id = x.id;

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