Get total hours worked in a day mysql

Question

I have a MySQL table where employee login and logout timings are recorded. Here in the in-out column 1-represents login and 0-represents logout.

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Answer 1

Rudi's line of thinking is correct. If you want the hours with decimal, use UNIX_TIMESTAMP() on the date_time field, otherwise the returned type will be a DATETIME (hard to parse). Here's the result for your first 4 lines of data plus 2 more for a different day:

SELECT 
    `user_id`, 
    DATE(`date_time`) AS `date`, 
    SUM(UNIX_TIMESTAMP(`date_time`)*(1-2*`in_out`))/3600 AS `hours_worked`
FROM `test` 
GROUP BY date(`date_time`), `user_id`;
+---------+------------+--------------+
| user_id | date       | hours_worked |
+---------+------------+--------------+
|       1 | 2011-01-20 |       3.2567 |
|       1 | 2011-01-21 |       3.0000 |
+---------+------------+--------------+