SQL Blog | LearnSQL.com

Who Should Learn SQL?

by Kamila Ostrowska

14 Apr 2021

If you learn SQL, will you use it in your current (or dream) job? If you learn it, will it help you with your daily tasks? SQL has so much potential that everyone can benefit from it – including you! Read this article to find out how much you will gain by knowing SQL. I could answer the title question with one word: everyone! But not everyone wants to learn SQL.

What FULL JOIN Is and When to Use It

by Zahin Rahman

13 Apr 2021

Learn about FULL JOIN, how to implement it, how it compares with the other types of SQL JOINs, and some of its unique use cases. Before we jump into FULL JOINs, let’s quickly recap what an SQL JOIN is. At its core, a JOIN combines data from two or more tables within a database. Tables are usually linked together using unique identifiers in each table, i.e. primary and foreign keys.

7 SQL JOIN Examples With Detailed Explanations

by Kateryna Koidan

9 Apr 2021

Do you need to join several tables to get the necessary result set? The SQL JOIN is a basic yet important tool used by data analysts working with relational databases. And I understand it can be difficult to choose from the zillions of introductory guides to joins. In this article, I will focus on real-world examples with detailed explanations. Introduction to JOIN With relational databases, the information you want is often stored in several tables.

SQL CTE Explained

by Zahin Rahman

8 Apr 2021

In this article, you will learn about SQL Common Table Expressions (CTEs). This powerful SQL tool will help you simplify complex queries. Additionally, I will introduce you to the two main types of CTEs and some of their use cases. CTE Primer The Common Table Expression (CTE) was introduced to standard SQL to simplify long, complex queries (especially joins and subqueries). It is a temporary data set returned by a query that contains data separate from the main query.

SQL Track of the Season: SQL Fundamentals in PostgreSQL

by Jakub Romanowski

7 Apr 2021

Are you ready for a new challenge this spring? Check out our SQL Track of the Season: SQL Fundamentals in PostgreSQL! In this article, we’ll answer common questions about this track. It’s getting warmer. The flowers are slowly beginning to bloom. This can mean only one thing – spring is here. The world is coming to life after its wintertime lethargy. This is a great time for new challenges. Do you want to add something to your skillset?

How to Find the Next Non-NULL Value in SQL

by Tihomir Babic

6 Apr 2021

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.

What Is the RANK() Function in SQL, and How Do You Use It?

by Kateryna Koidan

2 Apr 2021

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.

What Did the Easter Bunny Bring? Sweet Promotions for SQL Courses!

by Jakub Romanowski

2 Apr 2021

It's already spring and Easter comes with it. This time of year, the world comes to life. Maybe it's time to awaken your hunger for learning? There is a perfect opportunity for that: at LearnSQL.com we have sweet promotions for you! If you've ever thought about working with databases, you've probably also come to the conclusion that you need to learn SQL. It is an industry standard that should be in the arsenal of every aspiring programmer, analyst, or entrepreneur.

Free SQL Course of the Month – Creating Basic SQL Reports

by Jakub Romanowski

1 Apr 2021

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.

New Monthly SQL Practice for April 2021!

by LearnSQL.com Team

1 Apr 2021

Are you ready to use SQL skills to write queries that resolve business problems? Give it a try in the new Monthly SQL Practice on LearnSQL.com. The April SQL Practice is for people with a basic level of SQL proficiency. You will test your SQL skills based on data about an apartment rental agency in Chicago, USA. If this is the first time you’ve come across our Monthly SQL Practices, you should know that LearnSQL.

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