Group and sum worked hours by days - mysql

Question

I'm writing a software to manage worked hours. For each day could be different activities.
I wish to extract the worked hours for each worker in the last 7 days.
Sample rows
+----+------------+-------+----------+----------+
| id | date | order | operator | duration |
+----+------------+-------+----------+----------+
| 37 | 2016-06-12 | 27 | 1 | 180 |
| 38 | 2016-06-12 | 28 | 3 | 390 |
| 39 | 2016-06-12 | 27 | 1 | 480 |
| 40 | 2016-06-04 | 21 | 2 | 120 |
| 41 | 2016-05-07 | 27 | 1 | 90 |
| 42 | 2016-06-07 | 27 | 1 | 150 |
+----+------------+-------+----------+----------+
The Query
SELECT SUM(`duration`) as `hours_per_day`
FROM `sheets`
WHERE `operator` = 1 AND `date` = DATE_ADD(CURDATE(), INTERVAL -7 DAY)
ORDER BY `date` DESC
Expected result:
+------------------------+--------+--------+--------+--------+--------+--------+--------+
| Operator: Avareage Joe |
+------------------------+--------+--------+--------+--------+--------+--------+--------+
| Day: | 01 jul | 02 jul | 03 jul | O4 jul | 05 jul | 06 jul | 07 jul |
| Hours: | 8 | 7 | 9 | 8 | 9 | 8 | 6 |
+------------------------+--------+--------+--------+--------+--------+--------+--------+

Answer 1

SQL Fiddle Demo
SELECT
CURDATE(),
SUM(CASE WHEN CURDATE() = `date` THEN `duration` ELSE 0 END) as today ,
SUM(CASE WHEN CURDATE() - INTERVAL 1 DAY = `date` THEN `duration` ELSE 0 END) as yesterday,
SUM(CASE WHEN CURDATE() - INTERVAL 2 DAY = `date` THEN `duration` ELSE 0 END) as `today - 2`,
SUM(CASE WHEN CURDATE() - INTERVAL 3 DAY = `date` THEN `duration` ELSE 0 END) as `today - 3`,
SUM(CASE WHEN CURDATE() - INTERVAL 4 DAY = `date` THEN `duration` ELSE 0 END) as `today - 4`,
SUM(CASE WHEN CURDATE() - INTERVAL 5 DAY = `date` THEN `duration` ELSE 0 END) as `today - 5`,
SUM(CASE WHEN CURDATE() - INTERVAL 6 DAY = `date` THEN `duration` ELSE 0 END) as `today - 6`
FROM `work`
where operator = 1
OUTPUT

Answer 2

Let's try it like this:
SELECT operator, `date`, (SUM(duration) / 60) as hours_per_day
FROM sheets
WHERE `date` > NOW() - INTERVAL 7 DAY
GROUP BY operator, date
ORDER BY operator, date
Just look at the WHERE clause first. We exclude everything that is more than 7 days old.
Then we use GROUP BY to take all the remaining rows and group them by operator and date, so you basically get small sub-results that you can work with.
I retained your SUM(duration) operation, which now calculates sums for every one of these little sub-results. I just added the division, because obviously you're storing minutes, not hours.
Finally we use ORDER BY to make sure the result doesn't look like a big mess.
Your result should look something like this:
operator | date | hours_per_day
---------------------------------------
1 | 2016-07-01 | 4
1 | 2016-07-02 | 6
1 | 2016-07-03 | 6
2 | 2016-07-01 | 8
2 | 2016-07-02 | 7