Reducing ID duplication: How to minimize it?

Question

I have two tables and a linked table between them, One of the users and one of the holidays and the likes link table, I try to come up with all the holidays that a certain user doesn't like I got the same vacation twice because two other people liked her. Is there a way in NSQL to bring me only one of these.

These are users

id  u_name

1   Gabi    Ashkenazi   
2   Johnny  Tribiani    
3   Bernie  Stinson 
4   Goku    son 
5   Bo  Bennett

These are holidays

id  v_name

1   Venice
2   Rome
3   Maldives
4   Tokyo
5   Israel
6   Berlin
7   Prague
8   never Land

The link table is as follows

id  u_id   v_id
5   2       7
3   1       6
4   2       5
9   4       4

Answer 1

Is something like this useful to you? Find all the holidays Johnny likes and return a list of the ones he doesn't like:

SELECT * 
FROM Vacations 
WHERE v_name not IN 
(
  SELECT v_name 
  FROM Users 
  JOIN Linking 
  ON Users.ID = Linking.U_id 
  JOIN Vacations On Linking.v_id = Vacations.ID
  WHERE Users.ID = 2
);