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
SQL Query Fundamentals: SELECT, WHERE, Aggregation, Grouping, Sorting, and Limiting
This document covers essential SQL query operations, including selectign data, filtering with conditions, aggregating results, grouping data, ordering output, and limiting the number of rows returned.
Basic SELECT Syntax
The fundamental SELECT statement retrieves data from a table. The * wildcard selects all columns, while specific column names ...
Posted on Thu, 28 May 2026 22:12:24 +0000 by merkinmuffley