SQL query to select posts belonging to multiple categories

Question

I am writing a web application similar to a blogging software. There are three tables as below

Posts Table: Post_id,Post_Text
Post_Tags Table: Post_id,Tag_i         


        

Answer 1

Try this:

select * from posts where post_id in
(select post_id from post_tags pt join tags t on pt.tag_id = t.tag_id where tag_name = @yourtaghere)

or...

select
 p.*
from
 posts p join
 post_tags pt on p.post_id = pt.post_id join
 tags t on t.tag_id = pt.tag_id
where
 t.tag_name = @yourtaghere

If you have multiple tagnames you're trying to match replace tag_name = @youtagehere with tag_name in ('tag1','tag2','tag3',etc)