Articles Cookbook
28 Mar 2023
Tihomir Babic

How to Solve the “must appear in the GROUP BY clause or be used in an aggregate function” Error in PostgreSQL

Learn what causes one of the most common PostgreSQL GROUP BY errors and how you can fix it! As a PostgreSQL user, you surely encounter many error messages when writing an SQL code. Sometimes they are quite unclear, but you won’t need an interpreter for this one: “must appear in the GROUP BY clause or be used in an aggregate function”. This error message mentions GROUP BY and aggregate functions.
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23 Mar 2023
Jill Thornhill

How to Practice Advanced SQL Online

Want to go from intermediate to advanced SQL user? You’ll need to practice! Here are some ways you can practice advanced SQL online. You’ve seen how SQL helps you make data-driven decisions. Perhaps you’ve even learned some advanced features. But you’d like to become an expert—and for that, you need practice, practice, and more practice. Is it possible to get advanced SQL practice online? Taking SQL to the Next Level What is advanced SQL?
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21 Mar 2023
Kamila Ostrowska

Best MySQL Courses for Beginners

SQL is among the most important languages when it comes to dealing with huge amounts of data. If your job includes analyzing or collecting data and you feel that an Excel file is not enough, you need to learn or develop your SQL skills. And if you learn SQL, you also need to know one of its most popular dialects - MySQL. If you've made the decision to learn SQL, you've come to the right place.
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16 Mar 2023
Tihomir Babic

A Detailed Guide to the SQL COUNT() Function

You can count on this guide to give you detailed explanations (backed with examples) of all the typical uses of the COUNT() function. Knowing data aggregation is a necessary stepping stone in your journey to becoming an SQL master. This includes the COUNT() function – one of SQL's most often used aggregate functions. Data aggregation still counts as basic-level SQL knowledge. Having firm foundations ensures you don’t have holes in your knowledge, which makes learning more complex SQL concepts easier.
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14 Mar 2023
Jakub Romanowski

Learning SQL in Your Native Language is Finally Possible

Do you or someone you know speak English as a second language? Would you like to learn SQL online in your preferred language? Good news! Our awesome SQL courses are now available in French, Spanish, German, Italian, and Portuguese! SQL, or Structured Query Language, is a programming language used for managing and manipulating data in databases. It's an essential skill for anyone working with data, whether you're a data analyst, a software developer, or just someone who wants to understand how databases work.
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9 Mar 2023
Maria Durkin

The Best Apps to Learn SQL

Let us guide you to the best apps for learning SQL on the go. Do you want to learn SQL but you don't know where to begin? If so, you've come to the right place! In this guide, we'll go over the best apps for learning SQL. We'll look at what each app has to offer and how it can help you get started with SQL. Let’s go! What Is SQL?
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7 Mar 2023
Jill Thornhill

The Best YouTube Channels for Learning SQL

SQL is not hard to learn, and YouTube tutorials are plentiful. Are online videos the best choice for you? How do you find quality YouTube channels for learning SQL? So you’re thinking of learning SQL? Maybe your job includes working with data, or maybe you’re looking to further your career by upping your skills. Good choice! But what’s the best way to learn? You may decide that an SQL YouTube tutorial is the best choice for you at the moment.
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2 Mar 2023
LearnSQL.com Team

Free Course of the Month – SQL Practice Set in PostgreSQL

Do you know the basics of PostgreSQL but still need some practice? Look no further! Here is a great interactive course, SQL Practice Set in PostgreSQL. Throughout the month of March, you have access to it for FREE! We at LearnSQL.com believe that to learn a new skill, you need basic theoretical knowledge and, above all, a lot of practice. It's the same with writing PostgreSQL queries – you need a lot of PostgreSQL practice.
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28 Feb 2023
Ignacio L. Bisso

25 Advanced SQL Query Examples

One of the best ways to learn advanced SQL is by studying example queries. In this article, we'll show 25 examples of advanced SQL queries from medium to high complexity. You can use them to refresh your knowledge of advanced SQL or to review before a SQL interview. Many of the examples in this article will be based on the following employee table. Only a few examples will be based on other tables; in these cases, the tables will be explained along with the example.
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28 Feb 2023
LearnSQL.com Team

New Monthly SQL Practice for March 2023!

Ready for our new SQL challenge? This time, we have prepared slightly more difficult SQL tasks. Here’s the March SQL Practice course! This time, you will help Shelly who runs a coffee shop. Shelly would like to gather some data to expand the business and has hired you as an SQL specialist. Can you help her find the most popular menu items? Can you calculate the total revenue in December 2022?
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