18 Apr 2024 Tihomir Babic GROUP BY and Aggregate Functions: A Complete Overview SQL’s GROUP BY and aggregate functions are essential in data aggregation – and for analyzing data and creating reports. Let’s explore them together! In SQL, GROUP BY and aggregate functions are one of the language’s most popular features. Data aggregation is critical for data analysis and reporting; to make sense of all the data in a dataset, it often needs to be aggregated. But what is data aggregation? Put simply, it’s when you group data based on common values and perform a calculation for each data group. Read more 19 Mar 2024 Jill Thornhill SQL Aggregate Functions Cheat Sheet A quick reference guide to using SQL aggregate functions. This SQL Aggregate Functions Cheat Sheet is designed to be your companion whenever you’re using SQL for data analysis. Aggregating data is essential for any meaningful data analysis. SQL provides a set of functions that allow you to include totals, averages, and counts in your reports and to extract the minimum and maximum value of any column of data. Read more 21 Nov 2023 Maria Durkin SQL Aggregate Functions: A Comprehensive Guide for Beginners Are you curious about SQL aggregate functions and how they apply to real-world scenarios? In this article, we'll explore SQL aggregate functions, showcase real-world examples, and offer valuable insights on how to master them. Data aggregation is the process of taking several rows of data and condensing them into a single result or summary. When dealing with large datasets, this is invaluable because it allows you to extract relevant insights without having to scrutinize each individual data point. Read more 11 Aug 2022 Tihomir Babic How to Use Aggregate Functions in WHERE Clause Filtering data according to the result of an aggregate function is a common data analysis task. So how do you use aggregates in the WHERE clause? We’ll dedicate this whole article to answering that question. Combining aggregate functions and filtering based on their results is often used in data analysis – e.g. showing branches with total sales above X, countries where the number of posts is lower than Y, students with an average score below Z, and so on. Read more 7 Jun 2022 Tihomir Babic How to Combine Two Aggregate Functions in SQL Having trouble using two aggregate functions in one query? This article will show you how to do it the right way – actually, the two right ways. In data analysis and reporting, we often need to count the number of records or sum them up and then calculate the average of this count or sum. Translated to SQL logic, this is the aggregation of aggregated data, or multi-level aggregation. For aggregation purposes, there are the SQL aggregate functions. Read more 11 Nov 2021 Martyna Sławińska What Are Aggregate Functions in SQL, and How Do I Use Them? Data is your source of knowledge. And thanks to SQL aggregate functions, you can extract the precise knowledge you need from your data efficiently. Read along to find out more. The core SQL aggregate functions are the following: COUNT(column_name | *) returns the number of rows in a table. SUM(column_name) returns the sum of the values of a numeric column. AVG(column_name) returns the average value of a numeric column. Read more 26 Nov 2020 Kateryna Koidan Aggregate Functions vs Window Functions: A Comparison If you aren’t familiar with SQL’s window functions, you may wonder how they differ from aggregate functions. When should you use window functions? In this article, we’ll review window functions and aggregate functions, examine their similarities and differences, and see which one to choose depending on what you need to do. After you’ve tackled basic SQL, you’ll probably want to get into some of its more advanced functions. That’s great; these functions make reporting and analysis easier. Read more 31 Aug 2017 Aldo Zelen Common SQL Window Functions: Positional Functions Positional SQL window functions deal with data's location in the set. In this post, we explain LEAD, LAG, and other positional functions. SQL window functions allow us to aggregate data while still using individual row values. We've already dealt with ranking functions and the use of partitions. In this post, we'll examine positional window functions, which are extremely helpful in reporting and summarizing data. Specifically, we'll look at LAG, LEAD, FIRST_VALUE and LAST_VALUE. Read more 11 Jul 2017 Dejan Sarka Statistics in SQL: Measuring Spread of Distribution Besides knowing the centers of a distribution in your data, you need to know how varied the observations are. In this article, we’ll explain how to find the spread of a distribution in SQL. Are you dealing with a very uniform or a very spread population? To really understand what the numbers are saying, you must know the answer to this question. In the second part of this series, we discussed how to calculate centers of distribution. Read more 6 Jul 2017 Francisco Claria An Introduction to Using SQL Aggregate Functions with JOINs Previously, we've discussed the use of SQL aggregate functions with the GROUP BY statement. Regular readers of the our blog will also remember our recent tutorial about JOINs. If you're a bit rusty on either subject, I encourage you to review them before continuing this article. That's because we will dig further into aggregate functions by pairing them with JOINs. This duo unleashes the full possibilities of SQL aggregate functions and allows us to perform computations on multiple tables in a single query. Read more 27 Apr 2017 Maria Alcaraz NULL Values and the GROUP BY Clause We've already covered how to use the GROUP BY clause and some aggregation functions like SUM(), AVG(), MAX(), MIN(), COUNT(). In this article, we will explain how the GROUP BY clause works when NULL values are involved. We will also explain about using NULLs with the ORDER BY clause. The best way to master GROUP BY and NULL in SQL is through practice. I recommend the SQL Practice track at LearnSQL. Read more