Overlapping Interval SQL | Dataford Interview Questions

What SQL query would you use to find overlapping intervals in a table?

Assume intervals belong to a resource and have a start and end timestamp. Treat intervals that only touch at a boundary as non-overlapping, and exclude rows with missing or invalid bounds.

Output

One row per overlapping interval pair for the same resource
Columns: resource_id, interval_a_id, interval_b_id, overlap_start, and overlap_end
Include each pair once, ordered by resource_id, overlap_start, interval_a_id, and interval_b_id

Schema

intervals

Column	Type	Description
interval_idPK	INT	Unique interval identifier
resource_id	VARCHAR(30)	Resource to which the interval belongs
start_at	TIMESTAMP	Interval start timestamp
end_at	TIMESTAMP	Interval end timestamp

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