Articles Cookbook
6 Nov 2020
Magdalena Wojtas

Where to Go After Learning SQL Basics

Learning to code is – in general – a lot of fun, for sure. Even after a few years in the IT industry, I still love learning new technologies. And I now know that learning with a good plan is even better than learning without one. This also applies to learning with advanced SQL courses. In this article, I'll show you how learning paths can save you some time and a lot of frustration.
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4 Nov 2020
Jakub Romanowski

Kickstart SQL Learning with Our SQL Basics Course

Why learn SQL from our interactive online courses? Two reasons: 1) Power up your career. 2) Avoid being a noob. What does it mean to be a noob? “Noob” comes to us from the world of computer games. It’s a combination of “newbie” and “beginner”. It’s not a very nice word. It means that someone has found you an inexperienced player and (even worse) resistant to learning. This resistance is what’s important.
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3 Nov 2020
LearnSQL.com Team

Course of the Month: GROUP BY Extensions in SQL

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.
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29 Oct 2020
Tihomir Babic

What is COUNT(*), COUNT(1), COUNT(column), and COUNT(DISTINCT) in SQL?

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.
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28 Oct 2020
Tihomir Babic

What are SQL CTE Best Practices?

Are you wondering what the best practices for using common table expressions are? This article will help you learn when to use a CTE and how to write it. If you have heard about SQL CTEs, you have probably noticed they’re often mentioned together with subqueries. Sometimes, people think there’s no difference compared to the subqueries, and there’s often debate about whether a CTE or subquery should be used to get a particular result.
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27 Oct 2020
Kateryna Koidan

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

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.
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23 Oct 2020
Kateryna Koidan

How to Learn SQL Common Table Expressions (CTEs)

Common table expressions are very useful for organizing, traversing, and improving the readability of long SQL queries.  Moreover, recursive CTEs, which can reference themselves, solve problems that cannot be addressed with other queries. But how do you master common table expressions in SQL? In this article, I discuss the most effective strategies for learning CTEs and suggest how to address the common challenges of learning common table expressions on your own.
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22 Oct 2020
Ignacio L. Bisso

What is a Primary Key in SQL?

Primary keys are an important concept in SQL databases. They provide a unique ID for every row in a database table. As an SQL developer, you should know what primary keys are, what data values are allowed in them, and how to create them. Read this article to learn the ABCs of primary keys in 10 minutes. How to Identify Rows in a Table Tables are the main objects in an SQL database, and as you probably know, tables store records or rows.
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21 Oct 2020
LearnSQL.com Team

Is Learning SQL for Free Worthwhile?

Everyone likes to get something for free, even when it comes to SQL courses. But is free always good? Find out how and where you can learn SQL for free – in a way that’s worth your time. Beginner-friendly database courses and SQL tutorials often promise to teach SQL fundamentals like SELECT, WHERE, GROUP BY, HAVING, and ORDER BY. These commands are the basis of a powerful set of skills for entry-level jobs in data analysis or databases.
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20 Oct 2020
Adrian Więch

What Is a DBMS?

We generate vast quantities of data every day, and that data needs to be stored somehow. That’s where DBMSs come in handy. Find out what they are and how they relate to databases. If you go on a diet and simply want to keep track of your weight, you can probably use a piece of paper and a pencil. If you then want to chart your daily caloric intake, you’ll probably switch to something like a computer spreadsheet.
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