Mysql - double group by

mysql, sql

Solution

Use `distinct`

    SELECT DATE(created) AS con_date,
           COUNT(distinct word_id) AS con_per_day,
           GROUP_CONCAT(word_id)
    FROM connections
    WHERE created > (NOW() - INTERVAL 30 DAY)
    GROUP BY con_date

Problem

I've following query: ``` SELECT DATE(created) AS con_date, COUNT(*) AS con_per_day, GROUP_CONCAT(word_id) FROM connections WHERE created > (NOW() - INTERVAL 30 DAY) GROUP BY con_date ``` Counts words added per day. All good, but I want to count uniques! Note word_id has 14,14 in the last raw. This must be counted as 1. I thought double group_by would cut it, but it seems to be a wrong way to do it. Any ideas?

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