根据部署数据（Mysql / PHP）计算给定月份的work_days数

Question

I am working on Payroll System where an employee can be deployed on projects from any_date to any_date . Sample MySQL table below

id   empid  project_id     start_date                end_date 
1      1       2        2016-11-05 15:10:22    2016-12-11 15:11:21 
2      1       3        2016-12-13 15:26:10    2016-12-20 15:29:40 
3      1       2        2016-12-23 15:31:46    2017-01-18 15:32:35 

Now, if I want to calculate the number of days in given month worked on all projects, I am using Eloquent which translates to below query(I verified in DB::getQueryLog()) :

SELECT 
*
FROM
    payroll_project_tracks
WHERE
    empid = 1
        AND '2016-12-01 00:00:00' BETWEEN start_date AND end_date
        AND '2016-12-31 23:59:59' BETWEEN start_date AND end_date

After getting the rows that have deployments of given month (month = Dec 2016 here), I want to calculate Number of Days worked on all projects in a given month.

I am getting no results with the above query. Can anyone correct me or let me know if there is some better way of doing this.

Answer 1

I think that the query should be:

SELECT *
FROM payroll_project_tracks
WHERE
     empid = 1 AND
     start_date <= '2016-12-31 23:59:59' AND
     end_date >= '2016-12-01 00:00:00'

This query will return the 3 rows you provided, but will cut out the following:

4   1   2   2017-01-01 15:31:46 2017-01-18 15:32:35

is this ok?