Question

I need help writing a query. What I’m trying to do, is to check, if any category_id have both (or even more) given tag_id’s. I’m looking for most optimal query…

if any category_id have both (or even more) tag_id’s

id              int(10) NO  PRI     auto_increment
client_id       int(10) YES         
category_id     int(10) YES         
tag_id          int(10) YES 

sample data:

41  1   137 183
40  1   137 124
39  1   136 179
38  1   136 124
62  1   143 263
61  1   143 200
60  1   143 135
59  1   143 131
58  1   143 125

Answer 1

SELECT category_id
FROM Mytable
WHERE tag_id IN(183, 200)
GROUP BY category_id
HAVING COUNT(Distinct tag_id) = 2