Question

I have two tables

Topic
----------------------
id  title
----------------------
1   Loops
2   Control Structure
3   Basics

Chapters
------------------------------------------------------
id  book_id topic_id chapter_number
------------------------------------------------------
1   1       1       1
2   1       2       2
3   1       3       3
4   2       1       5
5   2       3       2
6   3       3       1

When searched for topics, I want to show book_ids that has chapters on those topics.
Book_ids that have topic 1 and 2: 1
Book_Ids that have topic 3: 1,2,3
BookIds that have topic 1 and 3: 1

This is my query:

SELECT DISTINCT chapter.book_id FROM chapter Inner Join topic ON topic.id = chapter.topic_id WHERE topic.id IN  ( '1,3');

but it return Book_ids of : 1 and 3 while it should only return 1. It seems my query returns union while it should return an intersection.

Can someone help me fixing it?

Answer 1

Here is SQLFiddle demo. Just replace '1,3' in this query to any set of chapters you need:

select book_id from Chapters
where FIND_IN_SET(topic_id,'1,3')
group by book_id 
having 
count(*) =
(length('1,3')-length(replace('1,3',',',''))+1)