Stuck on a Query

Databases
1

Greetings earthlings.

Im trying to make “Categories” only show ones that have atleast 1 “Posts” assigned to them. In other words, it won’t list a Category if it is empty.

My problem is I have two tables. I have this totally wrong, can anyone give me some advice?

SELECT
    c.id, 
    c.title
    
FROM 
    categories AS c
    
WHERE
    (
        SELECT     
            p.assign_category 
            
        FROM 
            posts as p
            
        WHERE 
            COUNT(p.assign_category) > 1
            
    )
2

How about something like this?

(Not sure I understand your table structure so bear with me):

SELECT c.id
     , c.title
  FROM categories AS c
LEFT OUTER
  JOIN posts AS p
    ON p.assign_category = c.cid
GROUP
    BY c.id
HAVING COUNT(p.assign_category) > 1;
3

You can probably do this much simpler with a grouped inner join?

SELECT
    c.id, 
    c.title
    
FROM 
    categories AS c, posts as p
    
WHERE
c.id = p.cid
GROUP BY c.id

This way it’s selecting all categories that have a correlating post row.

4

or may be like this

Select id,title from categories c
where exists(select (1) from posts p where assign_category=c.id)

5

Ohh I was not doing JOINS because I didn’t want to include anything in it, but I see you can do it this way. I am going to try a few of these out :slight_smile: Ty

That is exactly perfect!
I would explain why I dont want to inner join the two together but then Ill confuse myself trying to explain it Haha