[Solved] Given a table bookings(start_date, end_date) with rows:1) 2024-06-01 to 2024-06-052) 2024-06-04 to 2024-06-10What will this query return?SELECT * FROM bookings b1 JOIN bookings b2 ON b1.... | SQL

SQL - Advanced Query Patterns

Given a table bookings(start_date, end_date) with rows:
1) 2024-06-01 to 2024-06-05
2) 2024-06-04 to 2024-06-10
What will this query return?

SELECT * FROM bookings b1 JOIN bookings b2 ON b1.start_date <= b2.end_date AND b1.end_date >= b2.start_date WHERE b1.start_date <> b2.start_date;

APairs of bookings that overlap but are not the same booking

BAll bookings including self-joins

COnly bookings that do not overlap

DNo rows because of the inequality filter

Step-by-Step Solution

Solution:

Step 1: Analyze the JOIN condition
The JOIN matches bookings where their date ranges overlap using the overlap condition.
Step 2: Consider the WHERE clause
It excludes rows where start dates are equal, so it removes self-joins, leaving only overlapping pairs of different bookings.
Final Answer:
Pairs of bookings that overlap but are not the same booking -> Option A
Quick Check:
Overlap pairs excluding self = Pairs of bookings that overlap but are not the same booking [OK]

Quick Trick: JOIN on overlap condition and exclude self-joins [OK]

Common Mistakes:

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