MySQL跨多列计数，带有子查询，带有一个结果查询

Question

I have a table (kt2020) with fields (task1,task2,..pts,user,date). The same task can appear in multiple columns. To do a count by tasks, I have the subquery:

SELECT
    task,
    count(*)
FROM     (SELECT task1 AS task FROM kt2020 UNION ALL
          SELECT task2 AS task FROM kt2020 UNION ALL
          SELECT task3 AS task FROM kt2020 UNION ALL
          SELECT task4 AS task FROM kt2020 UNION ALL
          SELECT task5 AS task FROM kt2020 UNION ALL
          SELECT task6 AS task FROM kt2020 UNION ALL
          SELECT task7 AS task FROM kt2020
) t

group by task

What I'd like now is to create an outer query that further filters by user and date; smtg like this:

WHERE STR_TO_DATE(date, '%Y-%m-%d') >= CURDATE() - INTERVAL 7 DAY and user = 'username'

That would give me a result of tasks over the last 7 days, from user 'username'. Right now, these outer fields are hidden to the current query, and I don't know how to access 'date' or 'user' in the same query.

I guess I could bang out something long and cumbersome, but I'm sure there's a way that uses a common function I'm not aware of?

Answer 1

One option is the subquery to return date and user and then use a WHERE clause to filter:

SELECT
    task,
    count(*)
FROM     (SELECT task1 AS task, date, user FROM kt2020 UNION ALL
          SELECT task2 AS task, date, user FROM kt2020 UNION ALL
          SELECT task3 AS task, date, user FROM kt2020 UNION ALL
          SELECT task4 AS task, date, user FROM kt2020 UNION ALL
          SELECT task5 AS task, date, user FROM kt2020 UNION ALL
          SELECT task6 AS task, date, user FROM kt2020 UNION ALL
          SELECT task7 AS task, date, user FROM kt2020
) t
WHERE STR_TO_DATE(date, '%Y-%m-%d') >= CURDATE() - INTERVAL 7 DAY and user = 'username'
group by task