MySQL query date range - find common periods

Question

Please accept my apologies for a lack of attempted code.

I can't get my head around this - or even figure out if it's feasible!

I have a table filled with 'date slots', these can be booked by an individual.

The time slots table looks like this:

ID | Price | Available_from | Available_ to    
------------------------------------
 1 | 20.00 | 2017-10-01 | 2018-01-01
 2 | 20.00 | 2017-11-01 | 2017-12-07
 3 | 20.00 | 2017-10-31 | 2018-01-31
 4 | 20.00 | 2017-10-22 | 2017-11-21    
------------------------------------

In these rows, there is a common date range where all four results are available, 2017-11-01 > 2017-11-21

I would like to query my database to see if 1) there is a common range for every result and 2) if there is, get the date range.

Desperate for help!

Thank you

Answer 1

I think this would work :

SELECT  MAX(Available_from) as MatchFrom, 
        MIN(Available_to) as MatchTo
FROM Temporary.test
WHERE 
  (SELECT MAX(Available_from) FROM Temporary.test)
  <=(SELECT MIN(Available_to) FROM Temporary.test)

It will return NULL, if there is no overlapping range.