Articles Cookbook
17 Jul 2020
Dorota Wdzięczna

The LAG Function and the LEAD Function in SQL

LAG() and LEAD() are positional functions. A positional function is a type of window function. If you are not familiar with when and how to use them, what the syntax of each function is, why you might want to use them, and what the differences are, read on! LAG() and LEAD() are positional functions. These are window functions and are very useful in creating reports, because they can refer to data from rows above or below the current row.
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16 Jul 2020
Tihomir Babic

When Should I Use a Common Table Expression (CTE)?

Interested in hearing more about common table expressions or CTEs? Would you like to know when CTEs are useful? Read on—we’ll discuss in this article. If you’ve heard of common table expressions, you’ve probably wondered what they do. Even if you have not, it’s good that you’re here! CTEs can be very useful, especially if you have already mastered the basics of SQL, such as selecting, ordering, filtering data, and joining tables.
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15 Jul 2020
Jakub Romanowski

How to Learn SQL Fast

Are you in a rush to boost your data analysis capabilities? In this article, I'll show you how to learn SQL fast and become the Vin Diesel of data – how to become the "Fast and Querious". Step into the world of SQL with the easy-to-follow SQL from A to Z learning track from LearnSQL.com. Perfect for beginners with no IT background, this interactive series offers 7 hands-on courses where you learn by doing.
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14 Jul 2020
Ignacio L. Bisso

How to Calculate the Difference Between Two Rows in SQL

Calculating the difference between two rows in SQL can be a challenging task. It is possible – and there’s more than one way to do it. In this article, I’ll explain how to use the SQL window functions LEAD() and LAG() to find the difference between two rows in the same table. The best way to learn window functions is our interactive Window Functions course. It contains over 200 hands-on exercise that will teach you all window functions concepts, from simple OVER() clause to complex topics such as combining window functions and GROUP BY clause.
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10 Jul 2020
Adrian Więch

What Is Data Engineering?

Data Engineering is a fairly new term in IT. And it’s getting more and more attention. You may have heard about a few similar fields like data science, Big Data, and machine learning. This article explains the difference between these concepts and shows how they can be combined to analyze vast amounts of data. When computers first appeared, their storage capacity was very limited. Do you remember floppy disks? They were popular in the late 20th century and typically offered around 1.
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9 Jul 2020
Marija Ilic

What Is a CTE?

After mastering statements like SELECT, DELETE, INSERT, and GROUP BY, you might search for ways to improve code maintainability, reproducibility, and readability. At that point, you will probably start learning about modern SQL concepts that were introduced in the early 2000s. One such SQL technique is the CTE? (common table expression) —?a temporary named result set. In this article, you will learn what a CTE is and how to use it to improve the maintenance and the readability of your code.
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8 Jul 2020
Jakub Romanowski

Top 10 Laptops for Learning SQL in 2020

If you want to learn SQL, you’re going to need a device that’s portable and powerful. I recommend a laptop. Here are the features you’ll need, as well as my picks for laptops to get you learning SQL in 2020! I must admit that browsing Amazon’s computer offers or entering any computer store can give you a headache. So many models, with so many options! They differ in components, workmanship, battery life, and screen size and resolution.
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7 Jul 2020
Agnieszka Kozubek-Krycuń

What Is a SQL Dialect, and Which one Should You Learn?

SQL, standard SQL, SQL Server, MySQL, PostgreSQL, Oracle, … You’d like to learn SQL, but you feel overwhelmed with options and you don’t know where to start. We’ll explain what each of these terms mean and what this has to do with SQL dialects. Diving into the world of SQL dialects can feel like jumping into a deep pool without knowing how to swim. There's a ton of stuff to pick up!
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3 Jul 2020
Rebecca McKeown

Why Learn SQL for iOS and Android Development?

App and program development with iOS and Android is a huge and rapidly growing field in the software world. While some developers get through their careers knowing only their chosen development language, there are plenty of reasons to add SQL to that skill set. Here at LearnSQL.com, we are often asked: “why Learn SQL for iOS and Android development?” To answer that question, we’ve put together a little explanation about exactly why learning SQL makes sense for those in the app development space.
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1 Jul 2020
Marcin Koryszewski

Listen to These 7 SQL Podcasts

Are you learning SQL online but craving more? If you're looking for a way to squeeze some sweet SQL knowledge into your day, try listening to a SQL podcast. Choose one of our picks and get ready to amp up your SQL game! If you're like me, you like to get deep into a topic. You’re practicing it whenever there’s an opportunity. Of course, It’s hard to make time. I cherish the days I’m able to sit down and just get some hands-on learning done.
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