Question

I have a table Mark with id and name fields and second table with mark_id and two extra columns I’m interested in. I want to get all records from Mark table + priority for that mark and created_at. There might be several created_at values but I do not care much about them, I need just need one (first, whatever).

I tried this query which gives me too much records, 5 instead of 3 I expect.

SELECT 
    marks.*, 
    markings.created_at, 
    markings.created_at AS updated_at,
    markings.priority 
FROM `marks` 
JOIN markings 
    ON marks.id = markings.tag_id
WHERE (created_at > '2011-11-06 12:05:01') 
    AND (priority = 1) 
ORDER BY created_at;

Answer 1

SELECT 
    marks.*, 
    MIN(markings.created_at) as created_at, 
    MIN(markings.created_at) AS updated_at,
    markings.priority 
FROM `marks` 
JOIN markings 
    ON marks.id = markings.tag_id
WHERE (created_at > '2011-11-06 12:05:01') 
    AND (priority = 1) 
GROUP BY marks.col1, marks.col2, ... marks.coln, markings.priority
ORDER BY created_at;

where marks.col1, marks.col2, ... marks.coln would be marks.id, marks.name in your case if you don’t have more columns you don’t tell us about.