mysql query of coverage [closed] - mysql

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So I have a table of entries with a startdatetime and enddatetime, I want to be able to see overlap like employee coverage. For instance I have 10 employees on shift with different start times and end times and I want to be able to query by hour and see how many employees are available per hour.
I had not tried because I did not find a place to start, I do something similar when they is incoming tasks at a specific time to see how many in each hour, but I am trying to see coverage in each hour of the day based on when an employee starts and ends, like 8 hour shift, 12 hours shift, etc.. So That I can see that I have 2, 3, 4, etc... coverage and map to number of tasks that come in and are planned. Something below looks promising but its only for 1 time for each query, would like a query that can bring back each hour and how many cover in each hour.
Any help would be great.

Answer 1

Try something like this:
SELECT count(*) as TOTAL
FROM table
WHERE '2015-05-28 12:00:00'
BETWEEN startTime and endTime
Obviously you need to change this '2015-05-28 12:00:00' with the desidered date/time you're looking for.
Add others condition if needed...
EDIT
Adding the extra request:
Grouping by date and hour gives you the total count of coverage in a single hour per day.
SELECT date(date_start) as DAY, hour(date_start) as HOUR, count(*) as TOTAL
FROM table
group by date(date_start), hour(date_start)
You can abviously add one or more condition.
ie. in this example below you'll get the total rows per hour in a single day (specified)
SELECT date(date_start) as DAY, hour(date_start) as HOUR, count(*) as TOTAL
FROM table
WHERE date('2015-05-28') = date(startTime)
group by date(date_start), hour(date_start)