Range Joins on Dates | Dataford Interview Questions

How do you join tables on overlapping date ranges using range join conditions?

Asked in the Technical stage. Using the supplied tables, write a query that returns every pair of records whose inclusive date ranges overlap.

Output

One row per overlapping source and target pair
Columns: source_period_id, target_period_id, overlap_start, and overlap_end
Sort by source_period_id, then target_period_id

source_periods

Column	Type	Description
period_idPK	INT	Unique identifier for the source date range
period_label	VARCHAR(30)	Source range label
start_date	DATE	Inclusive start date of the source range
end_date	DATE	Inclusive end date of the source range

target_periods

Column	Type	Description
period_idPK	INT	Unique identifier for the target date range
period_label	VARCHAR(30)	Target range label
start_date	DATE	Inclusive start date of the target range
end_date	DATE	Inclusive end date of the target range

Your question is Range Joins on Dates. Start with the requirements and the two tables in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.