Question

I have the following mysql query:

SELECT id, sum(views) as total_views
FROM table
WHERE id IN (1,2,3)
GROUP BY id
ORDER BY total_views ASC

If only id 1,3 are found in the database, i still want id 2 to appear, with total_views being set to 0.

Is there any way to do that? This cannot use any other table.

Answer 1

Here’s an alternative to Micheal’s solution (not a bad solution, mind you — even with “a lot” of ID’s), so long as you’re not querying against a cluster.

create temporary table __ids (
  id int unsigned primary key
) engine=MEMORY;

insert into __ids (id) values
  (1),
  (2),
  (3)
;

SELECT table.id, sum(views) as total_views
FROM __ids left join table using (id)
GROUP BY table.id
ORDER BY total_views ASC

And if your query becomes complex, I could even conceive of it running more efficiently this way. But, if I were you, I’d benchmark this option with Michael’s ad-hoc UNION’ed table option using real data.