SQL Course of the Month – GROUP BY Extensions in SQL

3 Nov 2020 Do you want to develop your SQL skills? Do you want to get more out of your data and prepare better reports and summaries? The answer is learning to use SQL’s GROUP BY extensions. But how should you go about this? I asked the same question to Agnieszka Kozubek-Krycuń, Vertabelo’s Chief Content Officer. As she explains, the secret is in this November’s free SQL Course of the Month: GROUP BY Extensions in SQL.

What is the Difference Between COUNT(*), COUNT(1), COUNT(column name), and COUNT(DISTINCT column name)?

29 Oct 2020 Have you noticed there are different variations of the SQL COUNT() function? This article explains the various arguments and their uses. As a SQL user, you’re probably quite familiar with the COUNT() function. Even though it’s relatively simple, it can be used in several different ways. Each way has a very different use. I imagine you’ve seen code that contains the function COUNT(*) or COUNT(1). You’ve probably also seen some other uses of the COUNT() function, such as COUNT(column name) and COUNT(DISTINCT column name), even if you haven’t used them.

How to Fix a 'Not a GROUP BY Expression' Error

27 Oct 2020 Whether you are an experienced SQL user or only a beginner, your SQL queries may return errors. The accompanying messages are supposed to help you fix them; however, sometimes the messages are not very helpful. The Oracle message “Not a GROUP BY expression” is one such example. Let’s review what this is about and how to fix it. We are going to assume some basic understanding of how GROUP BY works.

GROUP BY in SQL Explained

15 Sep 2020 The SQL GROUP BY statement is easy to use, but it can be hard to master. Learn what you can do with GROUP BY, how it works, and how to use it with aggregate functions. GROUP BY is one of the basic SQL tools. However, it might be difficult for beginners to understand how GROUP BY works and how it is used to compute statistics with different aggregate functions. In this article, I’ll use several examples to show exactly how GROUP BY organizes rows and how aggregate functions can be used to calculate statistics on one or more columns.

How to Find Duplicate Values in SQL

2 Sep 2020 Duplicate records waste time, space, and money. Learn how to find and fix duplicate values using SQL’s GROUP BY and HAVING clauses. Database best practices usually dictate having unique constraints (such as the primary key) on a table to prevent the duplication of rows when data is extracted and consolidated. However, you may find yourself working on a dataset with duplicate rows. This could be because of human error, an application bug, or uncleaned data that’s been extracted and merged from external sources, among other things.

How Does SQL GROUP BY Work?

27 Aug 2020 Grouping results is a powerful SQL feature that allows you to compute key statistics for a group of records. GROUP BY is one of SQL’s most powerful clauses. It allows you to see data in a new way and find key metrics (like the average, maximal, and minimal values in a group of records). Without GROUP BY, all the results we obtain are oriented to records. With GROUP BY, we can create groups of records and calculate metrics on each group.

5 Examples of GROUP BY

20 Aug 2020 When you start learning SQL, you quickly come across the GROUP BY clause. Data grouping—or data aggregation—is an important concept in the world of databases. In this article, we’ll demonstrate how you can use the GROUP BY clause in practice. We’ve gathered five GROUP BY examples, from easier to more complex ones so you can see data grouping in a real-life scenario. As a bonus, you’ll also learn a bit about aggregate functions and the HAVING clause.

What Is the Difference Between WHERE and HAVING Clauses in SQL?

14 Aug 2020 As the amount of data in the world grows day by day, the need increases for managing and querying data efficiently. SQL offers ways to manipulate and query data at any scale. As an important part of this, the WHERE and HAVING clauses allow you to filter data as you need, but they are not the same. We will explain the differences between them in detail. One of the most common tasks in manipulating and querying data is filtering using the WHERE and HAVING clauses.

The SQL HAVING Clause Explained

31 Jul 2020 What is the SQL HAVING clause? Why do you need it, and where do you use it? We’ll explain HAVING in detail. HAVING is a very common clause in SQL queries. Like WHERE, it helps filter data; however, HAVING works in a different way. If you are familiar with the GROUP BY clause and have only heard about HAVING – or if you’re not familiar with HAVING at all – this article is what you need.

Using GROUP BY in SQL

21 Jul 2020 Now that you know SQL’s core commands, power up your queries with the GROUP BY clause and aggregate functions. GROUP BY is a SQL clause that arranges data into groups based on a common value (or values). It is widely used to obtain summary information for large datasets as well as for computing basic aggregate statistics. Once you have grasped SQL’s basic commands like SELECT, WHERE, and JOIN, mastering the GROUP BY clause can help you implement your SQL knowledge in real-world business intelligence scenarios.

What Is the Difference Between a GROUP BY and a PARTITION BY?

16 Apr 2020 Window functions are a great addition to SQL, and they can make your life much easier if you know how to use them properly. Today, we will address the differences between a GROUP BY and a PARTITION BY. We’ll start with the very basics and slowly get you to a point where you can keep researching on your own. PARTITION BY vs. GROUP BY The PARTITION BY and the GROUP BY clauses are used frequently in SQL when you need to create a complex report.

Difference between GROUP BY and ORDER BY in Simple Words

10 Dec 2019 For someone who is learning SQL, one of the most common places to get stuck is when learning the GROUP BY command. GROUP BY and ORDER BY are two important keywords in SQL that we use to organize data. The difference between GROUP BY and ORDER BY is that ORDER BY is more simple than GROUP BY and is usually introduced early in an SQL course. Sometimes, people are quite confused over these two concepts (SQL ORDER BY vs.

SQL Hacks To Control Family Budget On Black Friday Weekend

23 Nov 2017 If you’re in the US, chances are you’ve been eagerly awaiting the approach of Black Friday just as much as Thanksgiving. Though the shopping frenzy takes hold of nearly everyone, some people have to stick to their budgets and shop prudently. In this article, we’ll take a look at how generating an SQL report can help you track how much your family spent shopping on Black Friday. Storing Black Friday Purchases in a Database Before we can create an SQL report, we first need some data we can use.

A Beginner’s Guide to SQL Aggregate Functions

26 Jun 2017 Aggregate functions are powerful SQL tools that compute numerical calculations on data, allowing the query to return summarized information about a given column or result set. These functions can be used in conjunction with the GROUP BY statement. Let’s see how they work using some easy examples. SQL Aggregate Functions Suppose we have users residing in a city, and we store their information in two tables. These tables and their relationship are shown below:

Getting the Hang of the GROUP BY Clause

18 Jan 2017 GROUP BY is an important part of the SQL SELECT statement. But new SQL coders can run into some problems when this clause is used incorrectly. Here’s how to avoid those issues. You’re learning SQL. You know how to SELECT some data FROM a table and how to filter the data with a WHERE clause. You can process the data using aggregate functions (MIN, MAX, SUM, AVG, and others). But when you’re dealing with a lot of data, you may need to narrow it down even more.

GROUP BY Clause: How Well Do You Know It?

3 Dec 2016 The database can do different kinds of computations: it can add and subtract, multiply and divide, it can do computations on dates, it can count rows and sum row values, and so on. It can also do quite sophisticated statistics. The GROUP BY clause is the most basic way to compute statistics in SQL. It can be quite tough for beginners but it is really powerful. Let's look at the details of the GROUP BY clause, starting with the basics.