从MySQL中的Hierarchical Data获取数据

Question

我存储多级别类别。表格如下：

类别表

+-------------+---------------+--------------------+
| category_id | category_name | parent_category_id |
+-------------+---------------+--------------------+
|           1 | Clothing      | NULL               |
|           2 | Footwear      | NULL               |
|           3 | Men           | 1                  |
|           4 | Women         | 1                  |
|           5 | Shirts        | 3                  |
|           6 | T-Shirts      | 3                  |
|           7 | Jeans         | 3                  |
+-------------+---------------+--------------------+

company_category_mapping表

+------------+------------+-------------+
| cmp_cat_id | company_id | category_id |
+------------+------------+-------------+
|          1 |          7 |           5 |
|          2 |          7 |           6 |
|          3 |          7 |           7 |
+------------+------------+-------------+

我想根据company_id从类别表中获取所有类别，子类别，子子类别。我很困惑这是怎么回事。我可以为商店公司类别创建一个新表吗？

我想在下拉列表中显示输出。 我有三个下拉列表，一个是主要类别下拉列表，第二个是子类别下拉列表，第三个是子类别下拉列表。下拉是明智的，即不同的公司有不同的类别。

输出显示屏幕。

抱歉我的英文。

感谢您帮助我。

Answer 1

试试这段代码。

SELECT ROW_NUMBER()OVER(ORDER BY StartDate,BatchName) BatchId,
BatchName, StartDate, NoOfTrainee,
CEILING(SUM(NoOfTrainee) OVER(ORDER BY StartDate,BatchName) / 100.0) as LotNo
FROM BatchTable

关于company_id

  SELECT c1.`category_name` as `category` , c2.`category_name` as `sub-category`, c3.`category_name` as `sub-sub-category` FROM `categories` as c1
    LEFT JOIN `categories` as c2 ON c1.`category_id`=c2.`parent_category_id`
    LEFT JOIN `categories` as c3 ON c2.`category_id`=c3.`parent_category_id`
    where c1.`parent_category_id` IS NULL

如果您需要获取特定company_id的数据。

例如：company_id = 7

SELECT cm.`company_id`, c1.`category_name` as `category` , c2.`category_name` as `sub-category`, c3.`category_name` as `sub-sub-category` FROM `categories` as c1
LEFT JOIN `categories` as c2 ON c1.`category_id`=c2.`parent_category_id`
LEFT JOIN `categories` as c3 ON c2.`category_id`=c3.`parent_category_id`
INNER JOIN `company_category_mapping` as cm ON cm.`category_id`=c3.`category_id`
    where c1.`parent_category_id` IS NULL

Answer 2

试试此代码

  

我正在使用mysqli来避免问题和黑客入侵

$results = $mysqli->query( "SQL
SELECT *
FROM `categories` as c1
LEFT JOIN `categories` as c2 ON c1.`category_id`=c2.`parent_category_name`
LEFT JOIN `categories` as c3 ON c2.`category_id`=c3.`parent_category_name`
where c1.`parent_category_name` IS NULL");echo 'Results is: ' . $result;