Question

我有一个目的地（州）表，其中包含活动的主要级别类别和子类别。我的最终目标是输出xml导航链接，以便链接到：

每个目标固定链接（按目标slug名称按字母顺序排序）
类别

下面是我将使用sql查询生成的内容，因为它对查询有任何影响，但我不需要xml帮助来解决这个问题：

<item href="/destinations/alabama/">
    <list>
        <item href="/destinations/alabama/category/">
            <list>
               <item href="/destinations/alabama/category/sub-category/"></item>
            </list>
        </item>
    </list>
</item>
<item href="/destinations/maryland/">
    <list>
        <item href="/destinations/maryland/category/">
            <list>
               <item href="/destinations/maryland/category/sub-category/"></item>
            </list>
        </item>
    </list>
</item>

目前我有一个查询来获取子类别，但它没有考虑活动目的地。

SELECT

subcategories.name AS subcategory_name,
subcategories.slug AS subcategory_slug,
categories.name AS category_name,
categories.slug AS category_slug

FROM

subcategories

LEFT JOIN destinations_subcategories ON
destinations_subcategories.subcategory_id = subcategories.id

LEFT JOIN categories ON
destinations_subcategories.category_id = categories.id

WHERE
1=1 AND
subcategories.is_active = 1 AND
categories.is_active = 1

返回：

subcategory_name    subcategory_slug    category_name    category_slug
Fly Fishing         fly-fishing         Fishing          fishing

但是此查询不考虑活动的目标，因为可以映射非活动目标和活动类别之间的关系。我想我可能需要一个子查询抓住所有活动目的地，然后加入？

SCHEMA /行样本：

id    name       slug       active
7     Maryland   maryland   1

我的类别表，示例行：

id    name       slug       active
1     Fishing    fishing    1

子类别表格样本行：

id    name           slug           active
3     Fly-Fishing    fly-fishing    1

和2个表来存储关系，第一个将子类别映射到类别：

id    category_id    subcategory_id
5     1              3

第二个destinations_subcategories将目的地映射到子类别：

id    destination_id   category_id    subcategory_id
5     7                1              3

Answer 1

这个怎么样

SELECT

subcategories.name AS subcategory_name,
subcategories.slug AS subcategory_slug,
categories.name AS category_name,
categories.slug AS category_slug

FROM

destination 

INNER JOIN destinations_subcategories on destination.id = destinations_subcategories.destination_id and destination.active = 1

LEFT JOIN subcategories ON destinations_subcategories.subcategory_id = subcategories.id

LEFT JOIN categories ON destinations_subcategories.category_id = categories.id

WHERE 1=1 
AND subcategories.is_active = 1 
AND categories.is_active = 1

这将确保只显示活动目的地

Answer 2

SELECT destination.name , categories.name, sub-category.name 
FROM
destination_subcategories as ds, destinations, categories,  subcategories 
WHERE
ds.destination_id = destination.id and ds.catrgoy_id = category.id and ds.sub_category_id = sub_category.id and destination.is_active = 1 and categories.is_active = 1 and subcategory.is_active = 1;

这似乎应该有效，除非我误解了架构。

查询以选择活动目的地类别的子类别？

2 个答案: