Question

I have the classic ‘get all rows in one table with number of corresponding rows in another table’ issue which should be solved by this query:

SELECT
    ideas.id,
    ideas.idea,
    submitted,
    COUNT(votes.id) AS vote_count
FROM ideas
LEFT OUTER JOIN votes ON ideas.id = votes.idea
WHERE dead = 0
GROUP BY votes.idea
ORDER BY vote_count DESC, submitted DESC
LIMIT 10;

There are 4 rows (with dead = 0) in ideas and one row in votes (relating to the first idea). However this query returns two records (idea #1 and idea #2) with correct vote_counts. Why is this not returning all of the records in ideas?

Answer 1

When you say GROUP BY votes.idea, you are asking for one result row per idea value in votes. Since you say votes has only one row, you should expect only two records in the result — one corresponding to the idea value in that row of votes, and the other with NULL (condensing the three rows with no matching vote record).

Did you mean GROUP BY ideas.idea?