Question

I have two tables:

links

 | id | ...
   1
   2
  ...

clicks

 | linkid | userid | click_date |
    1     |   2    | ...
    4     |   2    | ...
    5     |   3    | ...

When users clicks a link from links it is added to clicks.

I want to use MySQL query to return only links that user hasn’t clicked – the pair linkid:userid isn’t contained in the table or click_date (secs from Unix epoch) was yesterday in GMT.

Answer 1

SELECT DISTINCT links_clicks.linkid FROM
(SELECT links.id AS linkid 
 FROM links 
 LEFT JOIN clicks ON links.id = clicks.linkid
 WHERE links.id IS NULL OR clicks.click_date <= CURDATE())
 AS links_clicks;