Question

The original question is the following:

Where A=1 AND A=2 returns 0 row problem – (Short Mysql question)

Thanks for some helpful answers. (but soon I realized I may have over-simplified the problem)

Actually the real problem is the following:

Tag 1,2,3 - category A
Tag 4,5,6 - category B
Tag 7,8,9 - category C

I want to achieve “OR condition” for the same category but “AND condition” for different category.
So I may want to return something like

-- I want id with Tag 1,4 or 1,2,4 but not 4
SELECT id FROM table WHERE Tag IN (1,2) AND Tag (4)

-- Tag 1,4 or 1,5 but not 1
SELECT id FROM table WHERE Tag IN (1) AND Tag (4,5)

-- Only Tag 1,4,9
SELECT id FROM table WHERE Tag IN (1) AND Tag (4) AND Tag (9)

I am trying to figure out from the answers, but any quick guide would be appreciated!

Answer 1

From my understanding you want to return ids that are tagged over at least 2 different categroies, try this:

Select id from Table 
WHERE tag_category in (A,B,C) 
Group by id 
Having count(distinct tag_category) >= 2