Check overlap of date ranges in MySQL

This table is used to store sessions (events):

CREATE TABLE session (
  id int(11) NOT NULL AUTO_INCREMENT
, start_date date
, end_date date
);

INSERT INTO session
  (start_date, end_date)
VALUES
  ("2010-01-01", "2010-01-10")
, ("2010-01-20", "2010-01-30")
, ("2010-02-01", "2010-02-15")
;

We don't want to have conflict between ranges.
Let's say we need to insert a new session from 2010-01-05 to 2010-01-25.
We would like to know the conflicting session(s).

Here is my query:

SELECT *
FROM session
WHERE "2010-01-05" BETWEEN start_date AND end_date
   OR "2010-01-25" BETWEEN start_date AND end_date
   OR "2010-01-05" >= start_date AND "2010-01-25" <= end_date
;

Here is the result:

+----+------------+------------+
| id | start_date | end_date   |
+----+------------+------------+
|  1 | 2010-01-01 | 2010-01-10 |
|  2 | 2010-01-20 | 2010-01-30 |
+----+------------+------------+

Is there a better way to get that?

---

fiddle

I had such a query with a calendar application I once wrote. I think I used something like this:

... WHERE new_start < existing_end
      AND new_end   > existing_start;

UPDATE This should definitely work ((ns, ne, es, ee) = (new_start, new_end, existing_start, existing_end)):

1. ns - ne - es - ee: doesn't overlap and doesn't match (because ne < es)
2. ns - es - ne - ee: overlaps and matches
3. es - ns - ee - ne: overlaps and matches
4. es - ee - ns - ne: doesn't overlap and doesn't match (because ns > ee)
5. es - ns - ne - ee: overlaps and matches
6. ns - es - ee - ne: overlaps and matches

---

Here is a fiddle

SELECT * FROM tbl WHERE
existing_start BETWEEN $newStart AND $newEnd OR 
existing_end BETWEEN $newStart AND $newEnd OR
$newStart BETWEEN existing_start AND existing_end

if (!empty($result))
throw new Exception('We have overlapping')

These 3 lines of sql clauses cover the 4 cases of overlapping required.

Lamy's answer is good, but you can optimize it a little more.

SELECT * FROM tbl WHERE
existing_start BETWEEN $newSTart AND $newEnd OR
$newStart BETWEEN existing_start AND existing_end

This will catch all four scenarios where the ranges overlap and exclude the two where they don't.

I had faced the similar problem. My problem was to stop booking between a range of blocked dates. For example booking is blocked for a property between 2nd may to 7th may. I needed to find any kind of overlapping date to detect and stop the booking. My solution is similar to LordJavac.

SELECT * FROM ib_master_blocked_dates WHERE venue_id=$venue_id AND 
(
    (mbd_from_date BETWEEN '$from_date' AND '$to_date') 
	OR
    (mbd_to_date BETWEEN  '$from_date' AND '$to_date')
	OR
    ('$from_date' BETWEEN mbd_from_date AND mbd_to_date)
    OR	    
    ('$to_date' BETWEEN mbd_from_date AND mbd_to_date)	    
)
*mbd=master_blocked_dates

Let me know if it doesn't work.

Given two intervals like (s1, e1) and (s2, e2) with s1<e1 and s2<e2
You can calculate overlapping like this:

SELECT 
     s1, e1, s2, e2,
     ABS(e1-s1) as len1,
     ABS(e2-s2) as len2,
     GREATEST(LEAST(e1, e2) - GREATEST(s1, s2), 0)>0 as overlaps,
     GREATEST(LEAST(e1, e2) - GREATEST(s1, s2), 0) as overlap_length
FROM test_intervals 

Will also work if one interval is within the other one.

Recently I was struggling with the same issue and came to end with this one easy step (This may not be a good approach or memory consuming)-

SELECT * FROM duty_register WHERE employee = '2' AND (
(
duty_start_date BETWEEN {$start_date} AND {$end_date}
OR
duty_end_date BETWEEN {$start_date} AND {$end_date}
)
OR
(
{$start_date} BETWEEN duty_start_date AND duty_end_date
OR
{$end_date} BETWEEN duty_start_date AND duty_end_date)
);

This helped me find the entries with overlapping date ranges.

Hope this helps someone.

You can cover all date overlapping cases even when to-date in database can possibly be null as follows:

SELECT * FROM `tableName` t
WHERE t.`startDate` <= $toDate
AND (t.`endDate` IS NULL OR t.`endDate` >= $startDate);

This will return all records that overlaps with the new start/end dates in anyway.

Mackraken's answer above is better from a performance perspective as it doesn't require several OR's in order to evaluate if two dates overlap. Nice solution!

However I found that in MySQL you need to use DATEDIFF instead of the minus operator -

SELECT o.orderStart, o.orderEnd, s.startDate, s.endDate
, GREATEST(LEAST(orderEnd, endDate) - GREATEST(orderStart, startDate), 0)>0 as overlaps
, DATEDIFF(LEAST(orderEnd, endDate), GREATEST(orderStart, startDate)) as overlap_length
FROM orders o
JOIN dates s USING (customerId)
WHERE 1
AND DATEDIFF(LEAST(orderEnd, endDate),GREATEST(orderStart, startDate)) > 0;