Скачать или смотреть LeetCode SQL Problem 183: Customers Who Never Order | Step-by-Step Solution Explained

In this video, we break down LeetCode Problem 183: Customers Who Never Order (Easy difficulty), a fundamental SQL interview question that tests your mastery of LEFT JOIN and handling NULL values to find non-matching records.
Problem Statement:
We have two tables:

Customers table: Contains id (primary key) and name.
Orders table: Contains orderId (primary key) and customerId (foreign key referencing Customers.id).

The task is to write an SQL query that reports the names of customers who have never placed any order (aliased as "Customers").
This problem is a classic example of finding records in one table that have no corresponding records in another — perfect for practicing anti-joins!
What You'll Learn:

How to use LEFT JOIN to include all customers and identify missing orders
Filtering with IS NULL to find non-matching rows
Alternative approaches using NOT EXISTS and NOT IN (and why NOT IN can be tricky with NULLs)
Difference between various anti-join techniques
Performance considerations in real-world databases
Common variations in interview questions (e.g., inactive users, unmatched records)

If you're preparing for SQL interviews (FAANG, analytics, backend roles), this pattern is extremely common!
🔗 Problem Link: https://leetcode.com/problems/customers-wh...

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