Question

I have the two following database tables:

News Table:

newsID, topic, categoryID

Category Table:

categoryID, title, parentID

I want to get the newsID, the topic, the title of the main category and only IF parentID is NOT 0, the title of the parent category.
Currently im stuck like that:

SELECT news.newsID, news.topic, category.title
FROM news
LEFT JOIN category
ON news.categoryID = category.categoryID
WHERE news.newsID = 1

I’m still missing the parent title if available. What’s the most performanced way to get it (if available)?

Thanks

Answer 1

Assuming that you have a categoryID column in the news table AND that the category table is a self-referencing hierarchy, meaning that a child’s parentID references the categoryID column of the parent row in the same table:

SELECT          n.newsID, n.topic, c.title, p.title as parentTitle
FROM        news n
LEFT JOIN   category c
ON         n.categoryID = c.categoryID
LEFT JOIN   category p
ON     c.parentID = p.categoryID
WHERE       n.newsID = 1