SQL Subqueries Tutorial

SQL Subqueries Tutorial

Overview Subquery is a powerful SQL tool. It enables users to do things that are not possible using common statements. Here are some common use cases of subqueries: In this post, I will show you how to use subqueries to get the data you need from your tables. Let’s get started. A Simple (and useless) … Read more

SQL Select Tutorial

SQL Select Tutorial

Overview Now you have your data populated (if you haven’t, please go back to the previous post) to complete the setup. In this post, I’m going to show you various way to query your data using the SELECT command. When using in combination with other clauses (such as WHERE, LIMIT), you can get exactly what … Read more

SQL Aggregation Tutorial

SQL Aggregation Tutorial

Introduction PostgreSQL provides a variety of built-in aggregation functions that allow you to calculate values such as count, sum, average, minimum, and maximum values for a set of rows. In this post, I’m going to walk you through the basic to advance aggregation functions. Let’s get started Basic Aggregation Functions You can use aggregation functions … Read more