Articles Cookbook
25 Nov 2020
Tihomir Babic

How to Find All Employees Under Each Manager in SQL

Have you ever been tasked with building an organizational chart – i.e. finding the employees under each manager in a company? In SQL, you can do that easier than you think! This article will show you how to get the answer using a recursive query. In the business world, it’s a very common task to list all the subordinate employees for a given manager. Is doing this hard enough to warrant a whole article?
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24 Nov 2020
Jakub Romanowski

SQL in the Open-Source World

Did you know there are free, open-source databases that use SQL? In this article, I'll show you which open-source database solutions can meet your needs. Ever wonder why many people still use paid programs when the same things can be done with free options? Personally, I am an avid supporter of the open-source movement. For years, I have been trying to apply and promote such solutions and support an active community around them.
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20 Nov 2020
Adrian Więch

How To Learn The SELECT Statement in SQL

When you think about learning SQL, one of the first things you come across is the SELECT statement. Selecting information is arguably the most important SQL feature. In this article, we’ll demonstrate the typical use cases for SQL SELECT with practical examples. Read this article if you’re a beginner database user and would like to know what SELECT can do for you. SQL, or Structured Query Language, is the programming language the IT world uses to communicate with databases.
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19 Nov 2020
Martyna Sławińska

What Is a SQL Constraint?

What are SQL constraints? When and why should you use them? We give examples of common constraints and demonstrate how to apply them. When you’re creating a relational database, you often want to impose certain restrictions on some columns. For example, a column containing a social security number should store only unique values; a column containing a date of birth should not be null, or left empty. These conditions can be ensured by using SQL constraints.
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17 Nov 2020
Agnieszka Kozubek-Krycuń

The History of SQL – How It All Began

Who created SQL and why? Find out in this article! Here’s a brief history of SQL, starting with its foundational concept: the database. Ted Codd and the Relational Data Model The first computer databases appeared in the late 1960s. This was an important area of research at the time. Many computer scientists were focused on improving how databases work. One of them was Edgar Frank (Ted) Codd, an English computer scientist employed at IBM.
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13 Nov 2020
Kamila Ostrowska

Practice SQL Before Interviewing a Potential Employee

Has your company grown to the point that you need to hire an SQL expert? Have you found a candidate for the job? How do you prepare for the interview, especially if you don’t know SQL? Don't worry! Follow our suggestions on how to practice SQL. We have tips and tricks to help you feel confident and find the perfect employee. Who You Want To Hire First of all, you need to know the requirements for the new employee.
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12 Nov 2020
Marija Ilic

SQL JOIN Types Explained

What’s the difference between INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN in SQL? When should you use each one? We’ve got your answers right here. You want to combine data from two or more different tables, but you’re not sure how to do it in SQL. There are different SQL JOIN types that you can use for different results. If you want to learn the differences between INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN, keep reading.
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11 Nov 2020
Zahin Rahman

Top 7 Online Courses for Data Engineers

This article summarizes the top online courses available for data engineers. We have picks suitable for beginners as well as intermediate learners. If you’re interested in database design and management, check these courses out! Most individuals who aspire to enter the realm of data aim for data scientist or data analyst roles. While these roles are indeed very rewarding because of their tangible links to customers and business direction, the role of data engineers is equally vital for businesses that operate in a data-rich environment.
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10 Nov 2020
Jakub Romanowski

SQL Terms Beginners Should Know

Have you started learning SQL? Do you feel a little lost in the maze of new words and ideas? Here’s a list of 10 absolutely essential SQL terms for beginners. When you start learning SQL, there’s a lot to process. And some of it – even basic SQL terms – gets lost in the shuffle. If this sounds like you, bookmark this article; it will be a handy reference.
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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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