Question

I just wanna ask best practice

supposed I have three tables. posts, categories, post_Categories. One post can have one or many categories

Post

post_id post_title      post_body
1   title 1             body1
2   title 2             body2

Categories

cat_id  cat_name
1       C#
2       Java
3       PHP

posts_categories

pc_id   pc_post pc_cat
1       1       1
2       1       2
3       1       3
4       2       2
5       2       3

I wanna display all post and its categries. and I can display list of post like this

title 1
body1
category(C#, Java, PHP)

-----------
title 2
body2
category(Java, PHP)

So I have to create query like this.

SELECT post_id, post_title, post_body, cat_id, cat_name  
FROM posts p INNER JOIN post_categories pc ON  p.post_id = pc.pc_post
INNER JOIN categories c ON c.cat_id = pc.cat_id

the result is 
1   title 1             body1   1   C#
1   title 1             body1   2   Java
1   title 1             body1   3   PHP
2   title 2             body2   2   Java
2   title 2             body2   3   PHP

after that, I must loop the post, and check if the title1 still have any category. if have, I must temp it to some variable. if not
I continue check the categories of title2 and temp it to some variable

after all, I display all post with its categories.

Is there any best practice than my code

Answer 1

You can use GROUP BY post_id and have a GROUP_CONCAT(cat_name SEPARATOR ', ') AS categories in you select list, but only if you don’t want to work with the IDs of categories, e.g. make them links.