Articles Cookbook
6 Apr 2021
Tihomir Babic

How to Find the Next Non-NULL Value in SQL

You need to find the next non-NULL value in a time series, but you don’t know how. Can you even do that in SQL? Yes, you can! This article will show you what to do. If you work with SQL, you will sooner or later confront NULL values. Having NULLs in a database is almost unavoidable. However, sometimes you want to avoid them in your reports. This is quite often true when you’re analyzing time series data; NULL values mean there’s no data available.
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2 Apr 2021
Kateryna Koidan

What Is the RANK() Function in SQL?

Who are your top 10 customers? Who are the top-performing employees in each department? To answer questions like these, you’ll need to rank the output of your SQL query. Let’s see how the RANK() function assists with ranking results in SQL. There are many use cases in which you might need to rank rows in SQL. You may want to rank customers based on the sales volume, students based on their exam results, company assets based on their present value, departments based on the number of employees, or users based on their date of registration.
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1 Apr 2021
Jakub Romanowski

Course of the Month: Creating Basic SQL Reports

Do you want to create good SQL reports from scratch? Are you looking for a course that will help you spread your analytical wings? What if I told you that throughout April 2021, you could access one of the best SQL Reports courses for FREE? Here it is: Creating Basic SQL Reports. What's the catch? There is none. LearnSQL.com provides one of their courses for free from time to time.
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31 Mar 2021
Andrew Bone

What Is CASE in SQL?

SQL CASE is a very useful expression that provides if-else logic to your SQL queries. It’s a slightly more advanced topic, but you’ll need it when preparing reports – it will deliver massive value to your personal and professional projects. The SQL CASE statement is a control flow tool that allows you to add if-else logic to a query. Generally speaking, you can use the CASE statement anywhere that allows a valid expression – e.
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26 Mar 2021
Dorota Wdzięczna

How to Install MS SQL Server 2019 on Windows

Do you want to install SQL Server 2019 on your Windows PC? How about the latest version of SQL Server Management Studio? I’ll walk you through the process. Soon you’ll be writing T-SQL queries and operating on SQL Server databases! As I write this article, Microsoft SQL Server 2019 is the latest version of SQL Server. It’s the 15th version of one of the most popular database servers in the world.
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25 Mar 2021
Jakub Romanowski

Is MS SQL Server Still Worth Learning in 2024?

MS SQL Server is an in-demand skill in today’s job market. Should you learn  MS SQL Server in 2024? In this article, I’ll answer this question. Thinking about whether you should dive into Microsoft SQL Server in 2024 – especially with so many free database alternatives available? MS SQL Server has been a go-to for handling data for ages, thanks to its solid features and reliability. But now, with a bunch of new options on the block, some people wonder if it's still the champ.
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24 Mar 2021
Ignacio L. Bisso

What Is a NOT NULL Constraint in SQL?

SQL has several ways of dealing with NULLs. In this article, we’ll focus on the NOT NULL constraint and other NULL-related clauses. Understand this and you’ll take an important step in your SQL growth! Before we get straight into the NOT NULL constraint, let’s quickly define what NULLs and constraints are. NULL values are a central concept in SQL databases. The idea behind a NULL value is simple: a NULL value means that we do not have a known value for that field.
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23 Mar 2021
Kamila Ostrowska

Best SQL IDEs for You

Maybe you just started learning SQL. Maybe you already have some experience. Whatever your situation is, choosing the right IDE for you is another step in your development. Why IDE? IDE stands for integrated development environment. It is a software application that enables us to combine various aspects of writing a computer program. An IDE usually contains a source code editor, build automation tools, and a debugger. You might ask why you need an IDE when you have the command line available on your computer.
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18 Mar 2021
Jakub Romanowski

New SQL Course: GROUP BY Extensions in PostgreSQL

Do you want to take your knowledge of PostgreSQL to the next level? I have something for you: LearnSQL.com’s new GROUP BY Extensions in PostgreSQL course! It will help you get even more out of your data and create better reports and summaries. Fasten your seat belts and prepare to see what GROUP BY can do when it’s turbocharged. First, I have to confess something. I am not objective – I think PostgreSQL is the best and coolest SQL dialect.
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17 Mar 2021
Gustavo du Mortier

What Is a NULL in SQL?

SQL uses NULLs as a special flag that signals the lack of a value for a field or a variable. NULLs should be used wisely so the database gives a faithful picture of the reality it represents. Some people associate NULLs with zeros; others think that NULL means “none”. In SQL, neither of these are true. Simply put, an SQL NULL means that we don’t have a value for that particular field.
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