SQL Aggregation Functions: An Essential Guide with Code Examples

SQL (Structured Query Language) is a powerful tool for working with databases, and aggregation functions are a crucial part of it. These functions allow you to perform calculations on sets of data and summarize information in various ways. In this article, we’ll explore SQL aggregation functions, what they are, and how to use them effectively with examples.

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What Are SQL Aggregation Functions?

SQL aggregation functions are used to perform calculations on groups of rows to return a single result. These functions summarize data, making it easier to extract meaningful insights from large datasets. Common SQL aggregation functions include COUNT, SUM, AVG, MIN, and MAX. Here's a brief overview:

Now, let’s dive into each of these functions with practical examples.

1. COUNT

The COUNT function is used to count the number of rows in a table or the number of non-null values in a specific column.

Example 1: Counting All Rows

SELECT COUNT(*) FROM table_name;

Example 2: Counting Non-Null Values in a Column

SELECT COUNT(column_name) FROM table_name;

2. SUM