Question

I’m making a sitemap. I have a table, which connects posts with categories (2 columns: categoryId, postId). There are nearly 9000 categories in total, and I want to count number of posts in each category to predict number of pages in pagination. I tried to do 9000 COUNT(*)’s for each category, but that is too slow (2 hours, actually). What can I do? Thanks.

Answer 1

You just have to do a SELECT COUNT and GROUP it by your categoryid like this :

SELECT C, COUNT(*) FROM yourtable GROUP BY categoryId as C

If you want only for a specific category, try to use WHERE categoryID = ?
before the GROUP BY