Multiple Apartments: Query Tenants with Multiple Apartments in SQL (CTCI 14.1)

TL;DR

• The Problem: CTCI problem 14.1 technical mechanics.
• The Approach: CTCI problem 14.1: SQL query using GROUP BY and HAVING to find tenants renting more than one apartment.
• Complexity: Optimal Time and Memory bounds.

This article provides a clear breakdown of CTCI problem 14.1.

1. Context and Problem Statement

CTCI problem 14.1: SQL query using GROUP BY and HAVING to find tenants renting more than one apartment.

2. Technical Code & Mechanics

SELECT TenantID, COUNT(*) AS ApartmentCount
FROM AptTenants
GROUP BY TenantID
HAVING COUNT(*) > 1;

3. Key Takeaways and Edge Cases

Always test boundary conditions and invalid input states.