Understanding the Filtering Differences Between LEFT JOIN and WHERE Clauses in SQL
Overview
This article explores the behavioral differences between placing filtering conditions in the ON clause of a LEFT JOIN versus the WHERE clause. The examples use two tables: a (with data) and b (empty).
Tables Setup
Table a
CREATE TABLE product_catalog (
record_id INT AUTO_INCREMENT PRIMARY KEY,
item_name VARCHAR(255) NOT NULL,
...
Posted on Mon, 15 Jun 2026 16:42:32 +0000 by rlelek