3NF database design ( And Conditions )

Question

I have a 3NF design (Tag , Item_Tag, Item)

As below but it wont work because i'm looping the same old cloumn multiple times.

I'm trying to Achive a list of tag with AND CONDITION. On OR condition , I Just have to do a whereIn but with a AND condition, I'm lost on how I can actually go head with it.

*More explanation*

ItemID TagID

203     45
203     60
203     61
203     62

204     45
204     50
204     51
204     52

Let's say I'm trying to get all ItemID Where Tag = 45 and tag = 60(And Condition)

This is my currently code and it wont work.

  $itemID = DB::table('item_tag')
                     ->where(function($query) use($ID)
                     {
                         foreach($ID as $uID){
                             $query->where('tag_id', '=', $uID);
                         }
                     })->lists('item_id');

Potential Solution 1

select * from question q inner join 
question_has_tag qt where tag_id in 
(select tag_id from tags where (what we want) 
minus select tag_id from tags where (what we don't)

Potential Solution 2

SELECT * FROM items WHERE  
    EXISTS (SELECT 1 FROM item_tag WHERE id = item_id AND tag_id = tag1)  
    AND EXISTS (SELECT 1 FROM item_tag WHERE id = item_id AND tag_id = tag2)  
    AND ...

Is this possible & how can I can do Solution 1 & 2 with Laravel 4. Thanks in advance.

Answer 1

select * from question q 
inner join question_has_tag qt 
    ON ...
where tag_id in (select tag_id from tags where (what we want)) 
    AND tag_id NOT IN (select tag_id from tags where (what we don't))

I think this is the logic you are looking for, note the missing ON clause.

If the tables are indexed properly you will probably be better off creating a #tmp table for (select tag_id from tags where (what we want)) and using inner joins rather than sub-queries.