Question

I am building a blog with Codeigniter and MySQL. The question I have is this, I have a table with posts and one with categories. I also have a cross reference table with post_categories. What I am trying to do is get all the categories with their names and the number of posts they have under their name.

Example output would be: Hello World(1) Test(0) etc.

What I am having a hard time finding is a SQL query that will join the three tables and get me the counts, and I am also having a hard time wrapping my head around how to make that query.

Here is my table schema:

blgpost
====
id
*Other schema unimportant

blgpostcategories
=================
postid
categoryid

blgcategories
==========
id
name
*Other schema unimportant

Answer 1

This should give you the output you want….

SELECT c.name, COUNT(p.id) FROM
blgcategories c 
INNER JOIN blgpostcategories pc ON c.id = pc.categoryid
INNER JOIN blgpost p ON pc.postid = p.id
GROUP BY c.id