Articles Cookbook
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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12 Mar 2021
Tihomir Babic

SQL JOIN Topics That Require Practice

Are you interested in learning how to join tables in SQL? Where do you start? Many JOIN topics require practice. In this article, we’ll explore these topics by writing codes to solve real-life situations. Hopefully, you will learn which JOIN topics require attention. To make it easier for you, the topics are divided into beginner, intermediate, and advanced. Joining two or more tables in SQL lifts data analysis to another level.
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10 Mar 2021
Jakub Romanowski

Where Can I Find Good Courses to Practice MS SQL Server?

Begin your journey to mastering MS SQL Server with the finest practice exercises out there. Whether you are a beginner or seeking to improve your T-SQL skills, explore the top destinations for the most engaging and interactive MS SQL practice courses online. You've started learning MS SQL Server. Maybe you've done a course, watched some YouTube tutorials, and feel pretty confident in your knowledge. What now? Let me tell you, you need to practice.
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9 Mar 2021
Kateryna Koidan

Why the SQL WITH Clause Is Awesome

If you’re not using WITH clauses yet, it’s definitely time to start! SQL WITH clauses, or common table expressions, help improve the structure of SQL queries by making them more readable. That’s already a lot, but WITH clauses have many more benefits. Let’s see together! The WITH clause was introduced in SQL:1999 to define views that are only valid for the query they belong to. Also known as common table expressions (CTEs), WITH clauses allow us to improve the structure of an SQL statement without polluting the database namespace.
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5 Mar 2021
Tihomir Babic

How to Get Descendants of a Parent in SQL

Want to learn how to handle family trees and find descendants of a parent? By reading this article, you’ll learn how to handle hierarchical data. Finding descendants from a parent is a common problem in SQL. If you imagine a family tree, the basic building block that forms the relationships within it is the parent-child relationship. The parent-child relationship is precisely what defines all hierarchical data. Another example of hierarchical data is the manager-employee relationship.
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4 Mar 2021
Andrew Bone

What Do the Operators LIKE and NOT LIKE Do?

The SQL LIKE and NOT LIKE operators are used to find matches between a string and a given pattern. They are part of standard SQL and work across all database types, making it essential knowledge for all SQL users. Gaining an understanding of these operators will allow you to write better queries and demonstrate to potential employers that you have the skills required to filter through expansive data sets.
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3 Mar 2021
Kateryna Koidan

How to JOIN Tables in SQL

Do you need to display data stored in different tables? Then it’s time to use SQL JOINs! This can be a challenging topic for beginners, so I’ve prepared this comprehensive step-by-step guide on joining tables in SQL. Often, the information that you want to display is stored in several tables. In such cases, you’ll need to join these tables by specifying which rows should be combined with other rows. That’s exactly what JOIN does.
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26 Feb 2021
Martyna Sławińska

MS SQL Server vs. PostgreSQL: Which to Choose?

Choosing the DBMS you will use for a new project is a very important and difficult decision. Two popular choices are MS SQL Server and PostgreSQL. To help you decide which would be best for you, I'll compare their features, list pros and cons, and give you some examples. Your selection of database management system (DBMS) depends on the type of business or project you're implementing. First, you need to know:
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25 Feb 2021
Timothy Edison

How Much SQL Practice Do You Need to Become a Pro?

Are you wondering how long it will take to learn and practice SQL before you can call yourself a pro? In this article, I will try to help you answer this question. Being a pro in SQL can mean many different things. Some people would say that being a professional is about mastery of advanced SQL, i.e. window functions or complex subqueries. For other people, being a professional means getting paid for your skills.
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