Question

I have two mysql tables and i want to do a select query: My objective is to calculate for a certain subscriber his points for the last seven days starting from the current time .
The first table presents for each subscriber the time he hits on a certain content from content id 1 2 or 3.
He could for a certain day have no content hits so he will not have points for this day.

The tables are shown in these pictures.
MY select query which is incomplete :

   SELECT SUM( points ) AS POINT, DAY FROM
 (SELECT content_hits.content_id, COUNT( * ) * points AS points, 
DATE_FORMAT( hit_time,  "%d-%m-%Y" ) AS  DAY 
FROM content_hits JOIN content 
WHERE content_hits.content_id = content.content_id AND subscriber_id =1
 AND DATE_FORMAT( hit_time,  "%Y-%m-%d" ) > ( CURDATE( ) - INTERVAL 7 DAY )
 GROUP BY content_hits.content_id, DAY) AS tm 
GROUP BY DAY 
ORDER BY DAY DESC

The result is shown in this picture:

I expects having a result with zero count for the days: 17-7-2102 16-7-2012 15-7-2012 14-7-2012 and 12-7-2012.
Any suggestion?

Answer 1

Need to create calendar table for use in left join

CREATE TABLE ints (i INTEGER);
INSERT INTO ints VALUES (0), (1), (2), (3), (4), (5), (6), (7), (8), (9);

Left join the calendar table to your query.

 SELECT cal.date,COALESCE(a.point,0) as point
 FROM (
    SELECT DATE_FORMAT(CURDATE() + INTERVAL a.i * 10 - b.i DAY,"%Y-%m-%d") as date
    FROM ints a JOIN ints b
    ORDER BY a.i * 10 - b.i
 ) cal LEFT JOIN 
 (SELECT SUM( points ) AS POINT, DAY FROM
  (SELECT content_hits.content_id, COUNT( * ) * points AS points, 
    DATE_FORMAT( hit_time,  "%Y-%m-%d" ) AS  DAY 
   FROM content_hits JOIN content 
   WHERE content_hits.content_id = content.content_id AND subscriber_id =1
     AND DATE_FORMAT( hit_time,  "%Y-%m-%d" ) > ( CURDATE( ) - INTERVAL 7 DAY )
   GROUP BY content_hits.content_id, DAY) AS tm 
   GROUP BY DAY 
 )a
 ON cal.date = a.day
 WHERE cal.date BETWEEN CURDATE( ) - INTERVAL 7 DAY AND CURDATE()
 ORDER BY cal.date desc;

SQL DEMO here.