MySQL "Trending" - mysql

Question

I'm selecting "ideas" from my database currently, but another requirement is to be able to grab "trending ideas", that is, the top 10 most-up-voted ideas within the last 7 days.
My query for selecting "ideas" is this:
SELECT
t.id AS 'id',
CONCAT(t.first_name, ' ', SUBSTRING(t.last_name,1,1)) AS 'name',
t.votes_up,
t.votes_down,
t.votes_aggregate,
GROUP_CONCAT(DISTINCT tags.name) AS 'tags',
t.createdon AS 'timestamp'
FROM (
SELECT
ideas.id, first_name, last_name, createdon,
COALESCE(SUM(case when value > 0 then value end),0) votes_up,
COALESCE(SUM(case when value < 0 then value end),0) votes_down,
COALESCE(SUM(value),0) votes_aggregate
FROM ideas
LEFT JOIN votes ON ideas.id = votes.idea_id
GROUP BY ideas.id
) as t
LEFT JOIN tags_rel ON t.id = tags_rel.idea_id
LEFT JOIN tags ON tags_rel.tag_id = tags.id
How would I get and display all the votes, but only get the "ideas" that have been voted up (votes_up) within the last 7 days and ordered by the amount of votes_up ?
This is my attempt:
SELECT
t.id AS 'id',
CONCAT(t.first_name, ' ', SUBSTRING(t.last_name,1,1)) AS 'name',
t.votes_up,
t.votes_down,
t.votes_aggregate,
GROUP_CONCAT(DISTINCT tags.name) AS 'tags',
t.createdon AS 'timestamp'
FROM (
SELECT
ideas.id, first_name, last_name, createdon,
COALESCE(SUM(case when value > 0 then value end),0) votes_up,
COALESCE(SUM(case when value < 0 then value end),0) votes_down,
COALESCE(SUM(value),0) votes_aggregate
FROM ideas
LEFT JOIN votes ON ideas.id = votes.idea_id
GROUP BY ideas.id
) as t
LEFT JOIN tags_rel ON t.id = tags_rel.idea_id
LEFT JOIN tags ON tags_rel.tag_id = tags.id
WHERE t.published = 1
AND (
SELECT ideas.id,
COALESCE(SUM(case when value > 0 then value end),0) votes_up
FROM ideas
LEFT JOIN votes ON ideas.id = votes.idea_id
WHERE votes.`timestamp` > (NOW() - INTERVAL 7 DAY)
GROUP BY ideas.id
) as v
GROUP BY t.id
ORDER BY v.votes_up DESC
But I get the error for the right syntax to use near 'as v GROUP BY t.id ORDER BY v.votes_up DESC LIMIT 10'

Answer 1

You're using the 'AS v' in a WHERE clause, which isn't possible:
WHERE t.published = 1
AND (
SELECT ideas.id,
COALESCE(SUM(case when value > 0 then value end),0) votes_up
FROM ideas
LEFT JOIN votes ON ideas.id = votes.idea_id
WHERE votes.`timestamp` > (NOW() - INTERVAL 7 DAY)
GROUP BY ideas.id
) as v

Answer 2

Try this one, in your SELECT statement you do the subquery, in your WHERE you check if this isn't NULL and you can order by it (if i'm right):
SELECT
t.id AS 'id',
CONCAT(t.first_name, ' ', SUBSTRING(t.last_name,1,1)) AS 'name',
t.votes_up,
t.votes_down,
t.votes_aggregate,
GROUP_CONCAT(DISTINCT tags.name) AS 'tags',
t.createdon AS 'timestamp',
(
SELECT ideas.id,
COALESCE(SUM(case when value > 0 then value end),0) votes_up
FROM ideas
LEFT JOIN votes ON ideas.id = votes.idea_id
WHERE votes.`timestamp` > (NOW() - INTERVAL 7 DAY)
GROUP BY ideas.id
) AS vup
FROM (
SELECT
ideas.id, first_name, last_name, createdon,
COALESCE(SUM(case when value > 0 then value end),0) votes_up,
COALESCE(SUM(case when value < 0 then value end),0) votes_down,
COALESCE(SUM(value),0) votes_aggregate
FROM ideas
LEFT JOIN votes ON ideas.id = votes.idea_id
GROUP BY ideas.id
) as t
LEFT JOIN tags_rel ON t.id = tags_rel.idea_id
LEFT JOIN tags ON tags_rel.tag_id = tags.id
WHERE t.published = 1
AND vup IS NOT NULL
GROUP BY t.id
ORDER BY vup DESC